The Effects of Change in Ionic Milieu and Electrical Stimulation on the Ionic Movements in Smooth Muscle

Sodium and potassium movements in the isolated preparation of guinea-pig's taenia coli soaked in high KCl Krebs solution and LiCl Krebs solution were estimated. In high KCl Krebs solution, both inward and outward movements of 42K were increased in proportion to the degree of depolarization. In LiCl solution 42K uptake was reduced though 24Na uptake was not influenced, 42K efflux increased and 24Na efflux was reduced slightly. The electrical stimuli of both 1V/cm and 10V/cm were effective to increase the efflux of 42K of taenia coli immersed in normal Krebs and in K2SO4 Krebs solutions, although in the latter medium, 1V/cm stimulus was ineffective to cause contraction. 24Na efflux was also increased by 10V/cm electrical stimulation in normal and in K2SO4 Krebs solution, though the change was not so significant as 42K results.