Modulation of active potassium transport by aldosterone

Abstract

1. 1. The role of aldosterone on active potassium transport across lizard colon under voltage-clamped conditions has been investigated. 2. 2. Control colons exhibited no net potassium flux ( J k net ) despite of the existence of active opposite unidi ectional fluxes. 3. 3. An important net secretory potassium flux was found in short-circuited aldosterone-stimulated colons. 4. 4. Mucosal amiloride did not change ( J k net) either in control or aldosterone-stimulated colons. 5. 5. Luminal barium alters K + transport in a manner consistent with the presence of barium-sensitive conductances at the apical membrane of both control and aldosterone-treated colons. 6. 6. The effects of ouabain and barium on control and aldosterone-induced potassium flows were consistent with a model involving basolateral uptake by an Na +-K +-ATPase and conductive exit across the apical membrane. 7. 7. The stimulatory effect of aldosterone on potassium secretion is associated with parallel increases of both basolateral K + entry and the apical conductive pathway.