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Effects of Food Intake and Anoxia upon Ascorbic Acid Excretion, Acidity of Urine, and Survival of Male Albino Rats¹

Department of Chemistry, Columbia University and the Nutrition Laboratory of Teachers College, Columbia University, New York

The effect of anoxia, induced by breathing a gas mixture low in oxygen at atmospheric pressure, on groups of male albino rats fed (a) dog chow alone, (b) a chow diet plus a daily supplement of 5 gm. of raw horse meat, (c) a chow diet plus a pre-exposure supplement of 2 gm. of sucrose, and (d) dehydrated carrots as the sole source of food, has been studied relative to the ascorbic acid, pH, and titratable acidity of the urine and to survival.

In all experiments anoxia caused an increase in the pH of the urine and a decrease in titratable acidity, which was accompanied by polyuria.

The ascorbic acid concentration of the urine varied roughly with the pH value over wide ranges, a high pH being accompanied by a low ascorbic acid value.

Increased alkalinity of the urine of animals fed a horse meat supplement, compared with animals fed chow alone, was not accompanied by protection of the animals against marginal lethal exposures to anoxia. Altitude tolerance was in fact slightly less in the meat-fed (high protein intake) groups.

Under the conditions of this experiment, a pre-exposure sugar supplement did not affect the altitude tolerance of rats on a chow diet.

When the consumption of chow was regulated equicalorically with the consumption of dehydrated carrots fed ad libitum, the two groups of animals survived severe anoxia almost equally well under some conditions of testing but in other tests, with an opportunity for adaptation by repeated exposures and more gradual ascent, there was evidence of added protection as a result of the carrot diet. The increased alkalinity, high potassium content and low protein content of the carrot diet afford a tentative basis of accounting for the increased tolerance.

² The experimental data given in the present manuscript were presented by one of the authors (K. E. L.) in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Nutrition, under the Joint Committee on Graduate Instruction, Columbia University.

Manuscript received 15 March 1945.