An assignment in the subject "Pharmacological and Toxicological Screening", 1st year, M.Pharm, Pharmacology, 1st semester. This presentation provides a brief knowledge about Pre-clinical Screening, Hypertension, Its Types, Normal body mechanism in Hypertension, Screening Procedures, Animal models, Animal model criteria, various screening procedures and their evaluation, Recent discovery, Hypertension Facts, Recent Discovery and Treatment for Hypertension.
In this slide contains diabetics, classification, symptoms, complication, invivo and invitro screening models of anti diabetics.
Presented by: GEETHANJALI ADAPALA (Department of pharmacology).
RIPER, anantapur
An assignment in the subject "Pharmacological and Toxicological Screening", 1st year, M.Pharm, Pharmacology, 1st semester. This presentation provides a brief knowledge about Pre-clinical Screening, Hypertension, Its Types, Normal body mechanism in Hypertension, Screening Procedures, Animal models, Animal model criteria, various screening procedures and their evaluation, Recent discovery, Hypertension Facts, Recent Discovery and Treatment for Hypertension.
In this slide contains diabetics, classification, symptoms, complication, invivo and invitro screening models of anti diabetics.
Presented by: GEETHANJALI ADAPALA (Department of pharmacology).
RIPER, anantapur
PRECLINICAL SCREENING MODELS
In vitro methods
• Patch clamp technique in kidney cells
• Perfusion of isolated kidney tubules
• Isolated perfused kidney
In vivo methods
• Diuretic activity in rats (LIPSCHITZ test)
• Saluretic activity in rats
• Diuretic and saluretic activity in dogs
• Clearance methods
• Micro puncture techniques in the rat
• Stop-flow technique
Introduction to Screening Models of Anti-Atherosclerosis
Atherosclerosis, Screening models, In vitro models, In vivo models
Presented by
SHAIK FIRDOUS BANU
Department of Pharmacology
PRECLINICAL SCREENING MODELS
In vitro methods
• Patch clamp technique in kidney cells
• Perfusion of isolated kidney tubules
• Isolated perfused kidney
In vivo methods
• Diuretic activity in rats (LIPSCHITZ test)
• Saluretic activity in rats
• Diuretic and saluretic activity in dogs
• Clearance methods
• Micro puncture techniques in the rat
• Stop-flow technique
Introduction to Screening Models of Anti-Atherosclerosis
Atherosclerosis, Screening models, In vitro models, In vivo models
Presented by
SHAIK FIRDOUS BANU
Department of Pharmacology
the structure of and formation blood cells, erythrocyte,leucocyte,neutrophil,basophil,eosinophil,lymphocyte T,lymphocyte B, hematopoiesis, erythropoiesis,leucopoiesis,granulocytopoiesis,agranulocytopoiesis,lymphopoiesis
This presentation consists of various approaches to treat hypertension depending on severity. It also include treatment according to international guidelines. Classification and brief description of each antihypertensive agent has been mentioned.
sceening of anti arrythmic drug by apurva.pdfApurva Pawar
screening method for anti arrhythmic drugs in preclinical pharmacology. In screening rats are used and the main method Legendroff's technique, various apparatus are used like board for a animal holding, O2 cyliner etc.
Presentation on all the evaluation methods in animals for anti-aarhythmics. It includes in vivo and in vitro methods. I have explained Langendorffs technique in detail.
Saludos! de parte del Ceipem (Centro de Entrenamiento e instrucción para profesionales en Emergencias Médicas), nuestra misión es brindar al profesional de la salud en un ambiente de simulación( Laboratorio de Simulación ), la oportunidad de adquirir habilidades y destrezas, desarrollar competencias individuales y/o grupales ante emergencias médicas, en los ámbitos pre e intra hospitalarios, contamos con el mejor Staff de profesionales para facilitar su aprendizaje. Cualquier información no dude en consultarnos, 0212 7314967/4063 /info@ceipem.org/ www.ceipem.org y si quieres ver fotos, videos y nuestras actividades ingresa por FACEBOOK en ceipem fundación y estarás en línea directa con nuestra comunidad de alumnos y docentes.
Advanced cardiac life support or advanced cardiovascular life support (ACLS) refers to a set of clinical interventions for the urgent treatment of cardiac arrest, stroke and other life-threatening medical emergencies, as well as the knowledge and skills to deploy those interventions.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
4. Recording of ECG in experimental animals
• Recording of the ECG is an essential tool in the evaluation of anti-
arrhythmic drugs. The pattern of ECG varies between species.
• Some changes:
Lead II between right foreleg and left hindleg, which is in line with neutrally
placed heart
Lead I between right and left foreleg stated to lie in the axis of horizontal
heart
Lead III between left foreleg and left hindleg in line with the vertical heart.
Along with these, unipolar leads (V1 to V6) and aVL, aVR and aVF.
• The procedure for recording of ECG in rats is as follows:
5. • Male Sprague Dawley rats 250-300 g
anaethetised by IP pentobarbitone 50 mg/kg
• Right jugular vein – injections and left
coronary for BP
• Lead II
• Electrode constructed with 26 gauge needles
placed subcutaneously
• Paper speed 100 mm/s on a student
physiograph
• Sensitivity of student physiograph adjusted
to provide deflection of 30 mm for 1mV
standard square wave
6. ECG recording (cont…)
• Variables measured:
σ T
P-R interval
QRS
Q-T
RSh
• Some differences between ECG of humans and smaller animals
Heart rate is very high
More prominent QRS
ST segment is generally absent
7. In vitro methods
• Isolated Guinea Pig papillary muscle
1. Characterization of anti-arrhythmic activity
2. Action potential and refractory period
• Lagendorff technique
• Ach or potassium induced arrhythmias
8. Isolated guinea pig papillary muscle
• A simple and accurate method to classify anti-arrhythmic drugs into
class I, II, III and IV.
• Based on the changes seen in
– Tension developed in papillary muscle (DT)
– Excitability (EX)
– Effective refractory period
9. Guinea pig (200-400 g) stunned and carotid artery severed
Thoracic cage opened and heart removed
Myocardium placed into a container filled with pre-oxygenated and prewarmed PSS
Right ventricle opened and tendinous end of papillary muscle ligated with a silk thread (connected
to a force transducer ).
Chordae tendinae freed from the ventricle and the other end clamped into a tissue holder and
platinum wire electrodes attached at its end
Preparation transferred to PSS and maintained at a constant temp and pressure
10. Muscles are field stimulated to contract
isometrically at stimulus duration of 1 ms at 1 Hz
frequency
Pulses delivered through a Grass constant voltage
stimulator and tension recorded through a
polygraph
Force frequency curve obtained by measuring
developed tension over a range of stimulation
frequencies
Percentage change in developed tension, ERP and
the strength duration curve noted
11. Action potential and refractory period in Guinea
pig muscle
• Guinea pigs of Marioth strain of 250-300 g
• Two strongest papillary muscles from LV taken
• Standard microelectrode technique is used to measure AP
• Stimulation is given by rectangular pulses of 1 V and 1ms duration at
500ms interval
• Second stimuli given in decremental intervals till contraction ceases
12. Lagendorff technique
Principle
• The heart is perfused in a retrograde direction from the aorta either
at a constant pressure or a constant flow with oxygenated saline
solutions
Animals
Albino rats (300g and at least 1 year of age)
New Zealand rabbits (1.5-3 kg and 3 years of age)
Guinea pig (300-450 g and 2-3 years of age)
13. Animal housing conditions
- Housed at ambient temperature (23⁰C ± 2⁰C)
- 12:12 hour light and dark cycle
- Free access to tap water
- Food ad libitum
Precautions
- Pretreatment with heparin
- Maintenance of PSS flow rate to prevent edema of cardiac tissue
- Prevent air bubble entry
- Maintain sufficient hydrostatic pressure by maintaining distance between
heart and the PSS reservoir
- Cannula shouldn’t penetrate the aortic valve
14.
15. Guinea pigs sacrificed by
stunning
Heart removed as
quickly as possible and
placed in a dish
containing PSS at 37⁰C
Cannula inserted into
aorta and tied and the
heart is perfused with
oxygenated PSSsolution
Oxygenated PSS solution
perfused at a constant
pressure of 40 mmHg at
37⁰C
Test compound
administered
Epicardial ECG electrode
used for pulsatile
stimulation and
arrhythmia induction
Steel hook with a string
is attached to the apex
FOC measured
isometrically by a force
transducer and recorded
on a polygraph
Incidence and duration
of VF or VT recorded in
both test and control
groups
16. Ach or potassium induced arrhythmias
• New Zealand white rabbits weighing 0.5-3 kg are used
17. New Zealand white
rabbits sacrificed and
heart removed quickly
Atria dissected and
attached to an
electrode in lower part
of bath and suspended
Fibrillation produced
when atria exposed to
Ach 3*10-4 or KCl 0.10 g
After 5 minutes of
exposure, rectangular
pulses given (0.75 ms
duration, 10V and)
Controlled arrhythmias
are produced and
allowed to continue for
6-10 minutes
30 minutes rest period
Fibrillation induced and
allowed to continue for
3 minutes
Test compound is
added to bath
18. Chemically induced arrhythmias
Chemical agents capable of producing arrhythmias are:
Anaesthetic agents like chloroform, ether, halothane (sensitizing agents)
followed by a precipitating stimulus such as IV adrenaline, aconitine, cardiac
glycosides (ouabain), veratrum alkaloids.
The sensitivity of these arrhythmogenic substances differs from species to
species.
19. Various models for chemically induced arrhythmias are:
1. Aconitine induced arrhythmia in rats
2. Digoxin-induced arrhythmia in Guinea pigs
3. Strophanthin/Ouabain induced arrhythmia in dog
4. Adrenaline induced arrhythmia in dogs
5. Calcium-induced arrhythmia in Wistar albino rats
20. Aconitine induced arrhythmia in rats
• Aconitine is a plant alkaloid - Aconitum
napellus root
• Can persistently activate sodium channels -->
ventricular arrhythmia in anaesthetised rats.
• Drugs with anti-arrhythmic property can be
tested in aconitine-intoxicated rats.
21. Procedure:
Animal – Male Ivanovas rats weighing 300-400 g
Anaesthesia – Intraperitoneal injection 1.25 g/kg urethane
• 5 μg/kg aconitine dissolved in 0.1 N HNO3 is infused into saphenous vein at
0.1 ml/min
• Lead II is recorded every 30 seconds
• Test compound given – oral or IV (3 mg/kg 5 minutes before aconitine)
22. Evaluation
The anti-arrhythmic effects are measured by amount of aconitine/100g
(duration of infusion) which includes
• Ventricular extra-systoles
• VT
• VF
• Death
Statistical significance is assessed by student’s t-test
23. Digoxin induced ventricular arrhythmias
• Overdose of cardiac glycosides can cause ventricular extra-systoles, VF
and death
• The occurrence of these symptoms can be delayed by anti-arrhythmic
drugs
Procedure
Animal – Male guinea pig (Marioth strain) weighing 350-500 g
Anaesthesia – 35 mg/kg pentobarbital sodium intraperitoneal
24. Trachea, a jugular
vein and a carotid
artery catheterised
Positive pressure
ventilation given with
a respiratory pump
BP monitored in the
carotid
Digoxin infused into
jugular vein 85 μg/kg
in 0.266 ml/min until
cardiac arrest
Treated group
receives the test drug
orally/IV 1 minute
prior to infusion
Control group
receives only digoxin
Period till ventricular
extra-systoles, VF and
cardiac arrest is noted
25. Evaluation
Doses of digoxin required to induce ventricular extra-systoles or VF or
cardiac arrest after treatment with anti-arrhythmic drugs are compared
statistically with student’s t-test
26. Strophanthin/Ouabain induced arrhythmia in dogs
Animal – Male or female dogs weighing 20 kg approximately
Anaesthesia – IV pentobarbital sodium 30-40 mg/kg
• Two peripheral veins are cannulated for administration of arrhythmia
inducing substance (V. brachialis) and for test substance (V. cephalica
antebrachii)
• Duodenum is cannulated for intraduodenal administration
• ECG is recorded with needle electrodes from lead II. Heart frequency
is derived from R-peaks of ECG.
27. • Strophanthin K is given continuous IV infusion at 3μg/kg/min.
• Signs of intoxication in the form of VT or multifocal ventricular arrhythmias
are seen in 30-40 minutes.
• Infusion is stopped. When the arrhythmia is stable for 10 minutes, the test
substance is given IV 1-5 mg/kg or intraduodenally 10-30 mg/kg.
• ECG is recorded at -0.5, 1, 2, 5 and 10 minutes following the test drug
administration
28. Evaluation:
For IV test drug administration
- Considered anti-arrhythmic if extra-systoles disappear immediately
- Increase the dose every 15 minutes if they don’t
For ID test drug administration
- Considered anti-arrhythmic if extra-systoles disappear in 15 minutes
- “no effect” if it doesn’t improve intoxication in 60 minutes
29. Calcium induced arrhythmias
Al-Obaid et al in 1998 used calcium chloride induced arrhythmias for
anti-arrhythmic activity evaluation in anaesthetized male rats
Wistar albino rats weighing 60-130 g are used
Anaesthesia – pentobarbital 60 mg/kg intraperitoneal
30. Arrhythmia induced
by a single IV
injection 10% CaCl2
(50 mg/kg)
Recovery allowed for
15-20 minutes
Test compound is
administered at
different doses IV
Effect of test
compound on basal
HR noted
After 7 minutes,
CaCl2 re-
administered
Effect of treatment
on induced
arrhythmia noted as
percentage change
31. Adrenaline induced arrhythmias
• Adrenaline can precipitate arrhythmia at high doses
• Dogs of 10-11 kg are anaesthetized by pentobarbitone sodium 30-40
mg/kg intraperitoneally.
• Adrenaline is given through femoral vein at 2-2.5 mg/kg
• Lead II ECG and atrial ECG are recorded
• Test drug given 3 minutes after adrenaline infusion
32. Some other models for chemically induced
arrhythmias
1. Mouse chloroform model (Lawson, 1968 and Vargafting, 1969)
2. BaCl2 model (Papp et al, 1967)
3. Benzene vapours induced arrhythmia (Tripathi and Thomas, 1986)
4. Wenzel and Kloeppel demonstrated that arrhythmias could be
induced by changing the medium of cultured heart cells
5. VF production by isoprenaline and COMT inhibitor at high
temperature (Sono et al, 1985)
6. Grayanotoxin – I induced arrhythmia in guinea pigs (Takei et al,
1994)
33. Electrically induced arrhythmias
1. Ventricular fibrillation electrical threshold
2. Programmed electrical stimulation induced arrhythmia
3. Sudden coronary death model in dogs (Harris dog model)
34. Ventricular fibrillation electrical threshold
Several electrical stimulation techniques are used to measure VF
threshold:
• Single pulse stimulation
• Train of pulses stimulation
• Continuous 50 Hz stimulation
• Sequential pulse stimulation
Animals – adult dogs weighing 8-12 kg
Anaesthesia – sodium pentobarbital 35 mg/kg intraperitoneal
35. Ventilation given with
Harvard respiratory
pump, systolic BP
monitored and body
temperature maintained
with a thermal blanket
Chest opened by a
midline sternotomy and
heart suspended in a
pericardial cradle
Sinus node crushed and
a 2mm diameter Ag-AgCl
stimulating electrode
embedded in a Teflon
disc sutured to ant wall
of LV
3-ms square anodal
constant current pulses
given for 400ms of basic
cycle and prematurely
restimulated
Recording electrode is
placed on the surface
of each ventricle
silver plate is implanted
under the skin in the
right femoral region as
indifferent electrode.
36. Lead II of the body surface
ECG is monitored.
To determine VF threshold, a
0.2-1.8 second train of 50 Hz
pulses is delivered 100ms
after every 18th basic driving
stimulus.
The current intensity is
increased from the diastolic
threshold in increments of
10μA to 1.0 mA or until VF
occurs.
Defibrillation given when VF
occurs,heart allowed to
recover to control conditions
for 15-20 minutes. Anti-
arrhythmic drugs are given in
the femoral vein.
37. Evaluation:
VF threshold is determined before and after test drug administration
and compared using student’s t-test.
38. Programmed electrical stimulation induced
arrhythmias
A ligature is tied around the
artery and needle. The
needle is then removed
which causes stenosis of the
vessel. LAD is perfused for 5
minutes.
Ischemic injury is achieved by
2 hour occlusion of LAD and
then again vessel is perfused
for 2 hours in presence of
stenosis.
During reperfusion, an
epicardial bipolar electrode is
sutured to the IV septum,.
Silver disc electrodes are
implanted SC for ECG
monitoring.
Animals with sustained VT
and VF are taken for study.
HR, ECG are recorded before
the PES is started.
After 6-9 days, the chest is
reopened and PES is
performed through electrode
implanted on non-infarcted
zone with pacing stimuli set
at 200ms.
After 15 pacing stimulation,
an extra stimulus is given
39. • Test drug is given 30 minutes after the stimulus.
• The minimum intensity of current needed for sustained VF is recorded
before and after test drugs and mean values of 10 experiments are
compared by student’s t-test.
40. Sudden coronary death model in dogs
• The group of Lucchesi described the experimental dog model for
protection against sudden coronary death.
Animal - Male Mongrel dogs of 14-22 kg weight
Anaesthesia - pentobarbital sodium 30 mg/kg IV.
41. Direct anodal 15μA current
from 9-V nickel-cadmium
battery passed through a 250
ohm resistor and applied to
electrode in the lumen of LCX.
Cathode connected to a SC
implanted disc electrode and
lead II ECG recorded for 30
seconds every 15 minutes on
a cardio-cassette recorder.
The animals are sacrificed
after 24 hours of constant
anodal current of at the
occurrence of VF.
Heart removed and thrombus
mass in LCX is removed,
weighed.
Heart sectioned and stained
with tetrazolium triphenyl
choride (TTC).
Time of onset of ventricular
ectopy and lethal arrhythmia
recorded using the cassette.
Non-sustained and sustained
tachyarrhythmia are
evaluated
42. Mechanically induced arrhythmias
Arrhythmias can be induced by directly by ischemia or and also by re-
perfusion. Studies involving both the mechanisms to produce
arrhythmias have been demonstrated.
1. Reperfusion arrhythmias in rats
2. VF after coronary occlusion and reperfusion in dogs
3. Two stage ligation in dogs (The Harris dog model)
43. Reperfusion arrhythmias in rats
• Ligation of left main coronary artery results in ventricular arrhythmias
and MI.
• ECG is recorded during ligation and also during reperfusion.
• The infarcted tissue is measured by tetrazolium triphenyl chloride
staining
44. Sprague Dawley
rats (350-400 g)
are anaesthetised
with
pentobarbitone
sodium 60 mg/kg
IP.
The animal is
maintained on
artificial
respiration, jugular
vein is cannulated
for drug
administration.
BP is recorded
from carotid artery
with the help of a
pressure
transducer
connected to a
polygraph.
Chest is opened
and heart is
exposed. The left
coronary artery is
located and ligated
for 15-90 minutes
(in case of infarct
size studies) and
subsequently
reperfused for 30
minutes.
45. Test drug is given 5 minutes before ligation.
The number of ventricular premature beats, VT and VF
are counted in the occlusion and reperfusion periods.
After the reperfusion period, the animal is sacrificed
and TTC staining is done to measure the infarct size..
Changes in hemodynamic parameters and infarct size in
drug treated animals are compared with control values.
46. Reperfusion arrhythmias in dogs
• Ligation of coronary artery in dogs may lead to increase in HR, LV end
diastolic pressure, BP and ventricular arrhythmias especially in
reperfusion.
• Animal - Dogs of 20-25 kg weight
• Anaesthesia:
thio-butobarbital sodium 30 mg/kg IP
maintained on IV chloralose 20 mg/kg and 250 mg/kg urethane IV followed
by SC morphine 2 mg/kg.
47. Changes in
parameters
(mortality,
hemodynamic and
arrhythmia) in drug
treated animals are
compared with
controls.
Coronary artery is
ligated for 90
minutes. Test
compound is given
20 minutes prior to
ligation and
reperfusion is done
after the ligation
period.
LV end diastolic
pressure and HR are
determined from LV
pressure curves.
Myocardial
contractility is
measured as a rise
of ventricular
pressure.
Femoral artery is
cannulated to
measure BP and
connected to a
pressure transducer
and ECG is recorded
continuously in lead
II.
48. Two stage ligation in dogs (Harris dog model)
• In 1950, Harris found that mortality in dogs after coronary occlusion
with a 2 stage ligation procedure was lower than with 1 stage ligation
49. Dogs of 8-11 kg are anaesthetised by IV injection of methohexitone sodium 10 mg/kg and
maintained on artificial respiration.
Chest is opened and the heart is exposed.
Left coronary artery is ligated in 2 stages. Two ligatures are tied around the artery and the 21
gauge needle.
1st ligature is tied around and the needle, which is removed
2nd is tied tightly around the artery (after 30 minutes ).
After 24-48 hours of ligation, arrhythmias develop and subside in 3-5 days.
50. • Lead II ECG, atrial electrogram and mean BP are measured.
• Test drugs are infused 10 minutes after coronary ligation.
• Changes in mortality, hemodynamics and arrhythmias in treated
animals are compared with controls.
51. Exercise induced ventricular fibrillation
• Billman and his group developed methods to evaluate anti-arrhythmic
drugs for their activity in exercise-plus-ischemia induced arrhythmia
test.
52. Mongrel dogs 15-19 kg are anaesthetised with sodium
pentobarbitone 10 mg/kg IV, chest cavity opened, heart
exposed and supported in a pericardial cradle.
Around the LCX a 20 MHz pulsed Doppler flow
transducer and hydraulic occluder are placed.
A pair of insulated silver wires are sutured to the
epicardial surface of both the left and right ventricular
electrogram.
A pre-calibrated solid state pressure transducer is
inserted into LV and finally a two stage occlusion of LAD
is done.
53. Leads are placed
under the skin to
exit on the back of
the animal’s neck.
3-4 weeks after the
production of
ischemia, the
animal is made to
walk on a motor
driven treadmill
during which
susceptibility to VF
is tested.
3 minute warm up
period - animals
run at 6.4 km/hr
(0% grade).
The grade is
increased every 3
minutes from 0%,
4%, 8%, 12% and
16%.
In the last minute
of exercise, the LCX
is occluded, the
treadmill stopped
and occlusion
maintained for an
additional minute.
54. • Repeated after the test drug and the findings are compared with the
control (saline) group.
• All hemodynamic data (rate of change of LV pressure) are recorded. The
refractory period data, reactive hyperemia response to each occlusion is
averaged and data analysed using ANOVA.
• The effect of intervention on arrhythmia formation are determined by chi-
square test with Yate’s correction.
55. Cell culture techniques
• Ventricular arrhythmias, especially torsades de pointes can be
evaluated using isolated ventricular myocytes.
• Analysis of action potential and patch clamp techniques in isolated
ventricular myocytes helps us to clarify mechanisms underlying
development of torsades de pointes.
56. Guinea pigs (250-350 g) are sacrificed by decapitation and their hearts are
removed and perfused retrodradely through the aorta at a rate of 10 ml/min
with oxygenated calcium free HEPES buffered saline at 37⁰C for 5 minutes.
Perfusion with same solution containing 300 U/ml type II collagenase and 0.5-
1.0 U/ml type XIV protease for 8 minutes
HEPES buffered saline containing 0.2mM calcium chloride for additional 5
minutes.
The cells re-suspended in HEPES buffered saline and stored at 24⁰C.
57. Transmembrane potential is recorded using glass electrodes connected to
the Axoclamp 2A amplifier.
Cells superfused with HEPES buffered saline at a rate of 2 ml/min at 37⁰C.
Passing brief current pulses (1 ms, 1.2 times threshold) through recording
electrode with active bridge current evokes action potentials.
Cells are stimulated at a frequency of 1 Hz during stabilization period and
at a frequencies of 1 and 3 Hz during control and 10 minutes after
superfusion with test drugs at cumulatively increasing drug concentration
58. Four individual AP are
digitally averaged and
measured for each
condition.
For voltage clamp studies,
microelectrodes made
from square bore,
borosilicate capillary
tubing are filled with 0.5
M potassium gluconate, 25
mM KCl, 5 mM K2ATP.
Voltage clamp is
performed using whole
cell recording mode and
cell perfusion is minimized
by maintaining constant
negative pressure on the
electrode using 1 ml
syringe.
Outward K+ currents are
measured during
superfusion of cells at 2
ml/min with calcium free
HEPES buffered saline.
Concentration response
relations are determined
by measuring AP of
currents in each cell
during control conditions
and during superfusion
with 2 successively
increasing concentrations
of a drug.
59. Genetically induced arrhythmias
• A certain breed of dogs – German shepherds – exhibit propensity to
sudden death that occurs due to inherited ventricular arrhythmias.
• Death usually occurs in them during sleep or at rest after exercise or
excitement.
• These dogs can be used for screening of potential anti-arrhythmic drugs.
60. Conclusion
• Species differences do exist in mechanisms producing arrhythmias and no animal can
exactly resemble humans
• However, knowledge acquired from animal studies can help a great deal in devising
therapeutic strategies for both ventricular and supraventricular arrhythmias
• Various animal models can be combined to build novel strategies in management of
arrhythmias
Editor's Notes
Precautions – handle the animal with care, keep the room calm
Storage oscilloscope
Compounds affecting ERP have either pro or anti-arrhythmic effects.
Inotropic effects can also be determined.
In 1897.was considered a breakthrough discovery in cardiovascular research.
Heparin to prevent thrombus formation in heart
Flow rate: 7-9 ml/min for rat,20 ml/min for rabbit
Rat, guinea pig – Krebs solution
Rabbit – McEwen’s solution
8-10 animals are used per compound
Urethane
The minimal current intensity of the pulse train required to induce sustained VF is defined as VFT.
1. 20 gauge needle.
2. by a silicon rubber snare (produces anterior wall infarction)
3. adjacent to the occlusion site
Sudden coronary death being the leading cause of death, it warrants for use of more complicated models in higher animals for discovery of active drugs.
The heart is dissected and cut into transverse sections (1 mm thick) and stained with TTC prepared in Sorensen phosphate buffer containing 100 mM, L-maleate to visualise the infarct tissue (blue/ violet stained healthy tissue and unstained necrotic tissue).
Slices are photographed and infarct area is measured by planimetry from projections of all slices
The experimental procedure is similar to rats.
3. from which HR is determined by Gould Biotachometer.
4. first partially occluded for 20 minutes and then tied off.
2. Analgesics and antibiotics are given to minimize the discomfort.
Defibrillation is given if animal becomes unconscious and the occlusion is released if VF occurs during experiment.
4. The heart is digested and cut into small pieces, placed in a 20 ml HEPES buffered saline containing calcium chloride and shaken until single cells are dissociated.
A list EPC-7 clamp amplifier is used to voltage clamp the isolated cells.
AP are assessed with three way ANOVA to determine significance within treatment variations. Dunett’s t test s used for significance of individual treatment means compared with control mean values.