The effect of ethanol on CO₂ production in mice Mus musculusKatherine 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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y = 46.768x - 969.58R² = 0.995

y = 80.724x + 887.62R² = 0.9971

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Alcohol is primarily digested in the body throughethanol oxidation. The primary oxidative pathway isperformed by the enzyme alcohol dehydrogenase (ADH)(McGuire, 2006). ADH, present in the stomach andsmall intestines of mice (Bolema, 1989), converts alcoholto acetaldehyde. The acetaldehyde is further oxidized toacetic acid, as a result, CO2 and water are produced viathe citric acid cycle. When alcohol is metabolized thereis a production carbon dioxide that is primarilyeliminated through the respiratory system (Carpenter,1937). It was predicted that alcohol would increase CO2

production. Laboratory mice, Mus musculus, were usedto 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 weekperiod, two separate days a week a part. On the first dayof research the mice were split into two groups; acontrol and experimental group. Mice 1-5 were givenethanol injections and mice 6-10 were given a controlinjections of saline solution. Eighty nine milliliters of 80proof (40% ethanol) will produce about a .15 BAC levelin 100 lb person; from these statistics mass specificinjections were calculated. This ensures that each mousewill metabolize an amount of alcohol that is proportionalto its body weight.

Each mouse was injected with its respectivesolution into the abdomen. Ten minutes was allowed forthe ethanol to metabolize, the mice were then put intojars and recording started via the Pasco GLX passportand CO2 probe. CO2 production was measured for 10minutes. Figure 1 shows mouse 2’s 10 minute timeframe for its’ CO2 production whilst metabolizing thealcohol and the control saline solution. Mice werehandled as little as possible before recording, andrecorded one at a time, to keep them calm andrespiration rate normal.

The following day two of research, the precedingprocedure was repeated and the two groups of micewere switched; mice 6-10 were given ethanol injectionsand mice 1-5 were given saline solution.

Saline had an average concentration of 12.98 ± 1.50mL 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 micedid not have a significant difference (p= 0.187, N=10).

References

The extent of this research project was to determinewhether alcohol metabolism increases CO2 production infasting mice. During the first trial there was a significantdifference between the ethanol injected and salineinjected mice. Mice that were injected with ethanolwere docile, they were motionless and were layingdown, though not asleep. Mice’s eyes were droopy if notclosed. Visually, respiration rate seemed to haveincreased. Saline injected mice, were hyper, climbing upthe jar and probe; which tapping or shaking the jarlightly would halt. Most of the saline mice spent theirtime cleaning, which is a natural, healthy behavior.During the second trial there was not much differencebetween saline and injected mice. There were severalfactors that could have modified the results. The micewere fasting for 12 hours, however, they were eating thepaper bedding in their tank. Their bodies were thentrying to metabolize the paper, and the paper is alsoabsorbing the alcohol, inhibiting maximal alcoholabsorption and metabolization.

Overall, there was no significant difference betweensaline and ethanol injected mice. Further experimentscould be done with a larger sample size and a morecontrolled environmental factors, such as housing andcontrolled 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. 417-420Boleda M. Dolors, Pere Julia, Alberto Moreno, and Xavier Pares (1989). Role of

Extrehepatic Alcohol Dehydrogenase in Rat Ethanol Metabolism. Achivesof Biochemistry and Biophysics Vo.274, No. 1: pp. 74-81