The influence of insulin on the respiratory metabolism of normal rabbits.

Abstract

The data to date on the respiratory changes resulting from insulin injections are conflicting. It is generally agreed that insulin causes a rise in R. Q. when administered to normal subjects but just how this change is brought about is still a matter of discussion. Is the increase in quotient due to increase in CO₂, decrease in O₂, or both?

Normal healthy rabbits were used as the experimental animals in this series of experiments. All were carried out under the same conditions as to care, diet, and time elapsing between food and experiments. Great effort was made to obtain comparable results. The blood sugar curve coincident with the respiratory change was followed. This also served as a check on the potency of the insulin.

From the findings to date the following summary seems justified:

1. Insulin, when administered to normal animals brings about, first a slight decrease, then a decided increase in the R. Q. curve, reaching the peak two hours after injection and returning to the basal level four hours after.

2. A blood sugar drop accompanies the R. Q. change, the lowest blood sugar occurring at the peak of the curve. The return to normal is less rapid than the return to normal of the R. Q. though the curve is well on its return by the end of the four hours.

3. There is, in the second hour, both a decrease in the 0₂ and an increase in the CO₂, both changes tending to increase the R. Q

4. The 0₂ consumption and the heat production would indicate that the total, metabolism is not markedly increased.