5. RPF= (aortic pressure-renal venous pressure)
renal vascular resistance
• Influences PGC
• Constriction of the afferent arteriole will result in a
decrease of PGC and GFR
• An increase in efferent arteriolar resistance will
increase PGC
7. TRIPHASIC PATTERN
1. For another RBF increases during
the first 1-2 hours and is
accompanied by a high PT and
collecting system pressure
2. 3-4 hours, the pres. remains
elevated but the RBF begins to
decline.
3. 5 hours after obstruction, further decline
in RBF occurs. A decrease in
PT and collecting system pressure also
occurs
9. Phase II &
III
An increase in afferent arteriolar resistance occurs causing a decrease RPF.
Angiotensin II, TXA2, Endothelin - preglomerular vasoconstriction during the 2nd and 3rd phase of
UUO
A shift in RBF from the outer to inner cortex also occurs further reducing GFR
(Decreased renal blood flow and unchanged ureteral pressure)
10.
11. TRIPHASIC PATTERN
1. For another RBF increases during the
first 1-2 hours and is accompanied by a
high PT and collecting system pressure
2. 3-4 hours, the pressure remains
elevated but the RBF begins to decline.
3. 5 hours after obstruction, further decline in
RBF occurs. A decrease in PT and
collecting system pressure also occurs
12. Effects of Obstruction on Tubular Function
Dysregulation of aquaporin water channels in the proximal tubule, thin descending
loop, and collecting tubule. Lead to polyuria and impaired concentrating capacity
Sodium Transport
Potassium and phosphate excretions follow changes in sodium
Deficit in urinary acidification
Magnesium excretion is increased after release of UUO or BUO
Changes in peptide excretion mark renal damage
13. Pathologic Changes of
Obstruction – Gross
42 hours - Dilation of the pelvis and ureter and blunting of the
papillary tips. Kidney is also heavier
7days - Increased pelviureteric dilation and the parenchyma is
edematous
21-28 days - External dimensions of kidneys are similar but
the cortex and medullary tissue is diffusely thinned
6 weeks - Enlarged, cystic appearing, weighs less than non-
obstructed kidney
No such changes observed in partially obstructed kidneys