Neurohumoral control of ionic pumping in molluscan muscle: III. Cholinergic control of the response to low potassium levels

Abstract

1. 1. Isolated radular protractor muscles (RPM) of Busycon canaliculatum show a complex response to potassium free solution. 2. 2. While exposed to a bathing solution lacking K +, the RPM begins to respond with a hyperpolarizing phase. Within minutes, this gives way to a depolarizing phase (DP). After readmission of a bathing solution containing K +, there is an extra hyperpolarizing phase. 3. 3. Acetylcholine over a range of concentrations from 10 −8M to 10 −3M progressively enhances the DP. 4. 4. The action of acetylcholine is sodium dependent.