Comparison of Diuresis Produced by Isotonic Saline Solutions and by Water in Rats Studied by a ‘Steady State’ Method

Abstract

New techniques, including use of a plastic restraining stall, indwelling gastric and intraven. catheters, and a recording balance, were developed so that small vols. of fluid could be administered to unanesthetized adult male rats while they were in a steady state of salt and water exchange, and so that the time course of the subsequent excretory responses could be measured precisely. Following admn. of 5 ml. of Ringer''s soln. through an indwelling gastric catheter, avg. urine flow rose promptly to 0.045 ml./min., andremained more than twice normal for 100 min. Excretion of Na, Cl and water corresponded to the amt. administered. Corresponding figures following admn. of 5 ml. of distilled water were 0.189 ml./min. and 50 min. Whenfluids were injd. continuously at increasing rates, urine flow balanced input of distilled water by gastric catheter up to 0.2 ml./min., Ringer''s soln. by gastric catheter up to 0.6 ml./min., and 0.15 [image].NaCl soln. by intraven. catheter up to 1 ml./min.