NA TRANSPORT BY ISOLATED TURTLE BLADDER DURING ANAEROBIOSIS AND EXPOSURE TO KCN.

Abstract

The isolated urinary bladder of the fresh-water turtle is lined with a single layer of epithelium, and in common with other polar epithelial cell tissues, actively transports sodium from mucosa to serosa in oxygenated Ringer's solutions. This transport is associated with a spontaneous potential gradient (serosa positive to mucosa). Of unusual biologic interest is the fact that Na transport is maintained under anaerobic conditions; and in contrast to frog skin and toad bladder, net rates of anaerobic transport averaged over 90% of aerobic values. Under aerobic conditions, the short-circuit current exceeded net sodium transport by approximately 15%. However, in deoxygenated Ringer's, net transport appreciably exceeded short-circuit current. With 10–3 m KCN, net transport not only persisted, but increased, and in common with the response in deoxygenated Ringer's, net Na flux to short-circuit current ratios increased. The isolated turtle bladder presumably is capable of providing energy for electrolyte transport via anaerobic metabolism. Because anaerobic glycolysis is less complex than oxidative metabolic pathways this structure could provide a valuable model for investigating energetics of active transport.