The study examined the effect of ethanol on carbon dioxide (CO2) production in mice. Mice were injected with either ethanol or a saline solution as a control and placed in jars, where CO2 production was measured over 10 minutes. On average, ethanol-injected mice produced more CO2 than saline-injected mice, however the difference was not statistically significant. The researchers hypothesized that ethanol would be broken down and increase CO2 production, but the results did not support this.

1. The effect of ethanol on CO₂ production in mice Mus musculus
Katherine Haxby, Richard Niederecker, and Alex Watson
Department of Biological Sciences, Saddleback College Biology, Mission Viejo
Introduction
Methods
Results
Discussion
Figure 1. Data was collected from the Pasco GLX passport, Mouse 2’s CO2 production over the span of 10
minutes from saline and ethanol values.
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AverageCO2Concentration(ppm)
Mice
y = 46.768x - 969.58
R² = 0.995
y = 80.724x + 887.62
R² = 0.9971
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Alcohol is primarily digested in the body through
ethanol oxidation. The primary oxidative pathway is
performed by the enzyme alcohol dehydrogenase (ADH)
(McGuire, 2006). ADH, present in the stomach and
small intestines of mice (Bolema, 1989), converts alcohol
to acetaldehyde. The acetaldehyde is further oxidized to
acetic acid, as a result, CO2 and water are produced via
the citric acid cycle. When alcohol is metabolized there
is a production carbon dioxide that is primarily
eliminated through the respiratory system (Carpenter,
1937). It was predicted that alcohol would increase CO2
production. Laboratory mice, Mus musculus, were used
to perform this experiment.
Figure 2. The average CO2 concentration of saline and ethanol. Saline had an average concentration of
27,439.1 ± 3,165.25 while ethanol had an average concentration of 31,674.4 ± 2734.30. Error bars are mean ±
SEM. A one tailed paired t-test revealed that the CO2 production between the experimental and control mice
did not have a significant difference (p= 0.187, N=10).
The experiment took place over a two week
period, two separate days a week a part. On the first day
of research the mice were split into two groups; a
control and experimental group. Mice 1-5 were given
ethanol injections and mice 6-10 were given a control
injections of saline solution. Eighty nine milliliters of 80
proof (40% ethanol) will produce about a .15 BAC level
in 100 lb person; from these statistics mass specific
injections were calculated. This ensures that each mouse
will metabolize an amount of alcohol that is proportional
to its body weight.
Each mouse was injected with its respective
solution into the abdomen. Ten minutes was allowed for
the ethanol to metabolize, the mice were then put into
jars and recording started via the Pasco GLX passport
and CO2 probe. CO2 production was measured for 10
minutes. Figure 1 shows mouse 2’s 10 minute time
frame for its’ CO2 production whilst metabolizing the
alcohol and the control saline solution. Mice were
handled as little as possible before recording, and
recorded one at a time, to keep them calm and
respiration rate normal.
The following day two of research, the preceding
procedure was repeated and the two groups of mice
were switched; mice 6-10 were given ethanol injections
and mice 1-5 were given saline solution.
Saline had an average concentration of 12.98 ± 1.50
mL while ethanol had an average concentration of 14.98 ±
1.29 mL as shown in figure 2. The average amount of CO2
produced was larger in mice that were injected alcohol.
However, a one tailed paired t-test revealed that the CO2
production between the experimental and control mice
did not have a significant difference (p= 0.187, N=10).
References
The extent of this research project was to determine
whether alcohol metabolism increases CO2 production in
fasting mice. During the first trial there was a significant
difference between the ethanol injected and saline
injected mice. Mice that were injected with ethanol
were docile, they were motionless and were laying
down, though not asleep. Mice’s eyes were droopy if not
closed. Visually, respiration rate seemed to have
increased. Saline injected mice, were hyper, climbing up
the jar and probe; which tapping or shaking the jar
lightly would halt. Most of the saline mice spent their
time cleaning, which is a natural, healthy behavior.
During the second trial there was not much difference
between saline and injected mice. There were several
factors that could have modified the results. The mice
were fasting for 12 hours, however, they were eating the
paper bedding in their tank. Their bodies were then
trying to metabolize the paper, and the paper is also
absorbing the alcohol, inhibiting maximal alcohol
absorption and metabolization.
Overall, there was no significant difference between
saline and ethanol injected mice. Further experiments
could be done with a larger sample size and a more
controlled environmental factors, such as housing and
controlled fasting.
Carpenter, Thorne M. (1937). The Metabolism of Alcohol in the Animal Body.
The Scientific Monthly. Vol. 45, No 1, pp 5-18.
McGuire L.C., Cruickshank A. M., Munro P.T. 2006. Alcoholic Ketoacidosis,
Emergency Medicine Journal. pp. 417-420
Boleda M. Dolors, Pere Julia, Alberto Moreno, and Xavier Pares (1989). Role of
Extrehepatic Alcohol Dehydrogenase in Rat Ethanol Metabolism. Achives
of Biochemistry and Biophysics Vo.274, No. 1: pp. 74-81