Estelle E. Hawley

Rate of Urinary Excretion of Test Doses of Ascorbic Acid

Summary The rate of excretion of ascorbic acid was determined after the oral and intravenous administration of test doses to unsaturated and saturated subjects. In those subjects whose reserves of vitamin C had been depleted, there was only a slight increase in the rate of excretion during the first few hours, regardless of the method of administration. In saturated subjects, an average of 80 to 85% of the total 24-hour excretion occurred during the first 12 hours after administration of the test dose. When the latter was given intravenously, maximum excretion occurred during the 1st and 2nd hours. After oral administration, maximum excretion occurred during the 3rd, 4th, 5th, and 6th hours.

Capillary fragility and vitamin C.

Summary 1. Determinations of capillary resistance to negative pressure were made in 100 normal individuals. 2. Attention is called to the high degree of variation in values for the capillary resistance in normal subjects. 3. Variations in the vitamin C intake of normal individuals, under the conditions of these experiments, had no significant effect on the capillary resistance.

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

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.

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

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.