Localization of Diuretic Action of Chlormerodrin in the Nephron of the Dog

¹ From the Department of Physiology, Cornell University Medical College, New York City

The stop flow method of Malvin, Sullivan and Wilde (Physiologist 1:58, 1957) has been applied in a study to localize the diuretic action of chlormerodrin in the nephron of the dog. It has been observed that under stop flow conditions, chlormerodrin reduces both the U/P ratio for creatinine in the proximal tubule and the gradient against which the proximal tubule can reabsorb sodium and chloride ions. These results are interpreted as indicating partial inhibition of active transport of sodium and/or chloride ions in the proximal segment of the nephron and equivalent reduction in the osmotic back flow of water. The reabsorption of sodium and/or chloride ions is inhibited in the same portion of the tubule which secretes the diuretic and which secretes p-aminohippurate. These experiments provide no evidence for inhibition of reabsorption of sodium of sodium and chloride ions by chlormerodrin in the distal tubule.