Significance of change in oxygen absorption after insulin in normal rabbits.

Abstract

Respiration experiments by the closed circuit method employing an apparatus which gave perfect control checks are reported upon twenty fasting rabbits. Seventeen of these received an injection of insulin subcutaneously which reduced the blood sugar an average of 62 mg. in two hours. One of two basal periods of 45 to 60 minutes each were obtained before giving insulin, and two periods of at least 45 minutes each, in all cases, and four periods in five of the cases, were obtained after insulin. There was no rise but often a fall in respiratory quotient during the first period up to one hour after insulin. In the second period, however, the average respiratory quotient was 0.98 in contrast with the average of 0.74 in the pre-insulin period. In the third period after insulin, the respiratory quotient returns to the normal level and persists also in the fourth period. The oxygen absorption on the average rises the first hour and falls considerably below the pre-insulin level the second hour. The CO₂ elimination rises the first hour and the average for all the animals rises still farther the second hour. But the average for the five animals studied longest the CO₂ does not rise farteher in the second period, and falls toward but does not quite reach the pre-insulin level in the third and fourth periods.

Calculations of the metabolism, by the Zuntz and Schumburg method, of several animals in which the urinary nitrogen was known, shows in the first hour after insulin an average increase amountinig to 16 per cent. In the second period terminating at 1% hours after insulin, there is an ablrupt change in the metabolism from fat to Carbohydrate.