The Effects of Barium Ion on the Resting and Action Potential of Intestinal Smooth Muscle Cell

Abstract

The effects of Ba ion on the resting and action potential of the intestinal smooth muscle cell of guinea-pig taenia coli were examined with an intracellular microelectrode. The lowest effective concentration of Ba was 0.05 m [image] which produced a slight increase in the frequency of spontaneous spike discharge. When the concentration of Ba was increased up to 1.4 m[image], the duration of action potential was increased and the prolonged depolarizations topped with multiple spikes were recorded frequently. The complete recovery was obtained by washing out Ba. A higher concentration of Ba (more than 2.2 m[image]) produced the rapid fall in membrane potential and cessation of spike discharge. These changes caused by high concentration of Ba were incompletely reversible, even after long soaking in normal Krebs''s solution.