Urinary Composition During Hypothermia

Abstract

Five dogs were cooled artificially to 22°C and then warmed to 37°C. Blood and urine chemical changes were periodically studied. An increase in whole blood ph and a decrease in serum potassium were observed; and little change in hematocrit, serum Na, Cl or total CO₂ concentrations occurred during cooling. Both blood ph and serum potassium concentrations returned to normal values upon warming the animals. Urine flow increased with cooling and the U/P ratios of sodium, potassium and chloride approached unity as body temperature was progressively lowered. The U/P ratio of creatinine dropped from 150 to 8. The ability of the kidney to produce ammonia or to acidify the urine decreased in a linear manner as cooling progressed and returned promptly upon warming. The changes in volume and composition of the urine which were produced by cooling, indicate that such urine is essentially glomerular filtrate which has undergone isosmotic reabsorption but which has remained unaltered by further renal tubular activity.