The Effect of Potassium on Frog Stomach Muscle

Abstract

1 KCl relaxed strips of frog stomach muscle. Usually, the effect was biphasic, i.e. contraction followed by relaxation at a concentration of 137 mm. 2 The effect was mimicked by K2SO4. 3 Ouabain (5 and 10 jg/mI) blocked the relaxations and reversed them to contractions. The tension of strips was not affected. 4 Phenoxybenzamine (1 pg/ml) and procaine (20 ig/ml) inhibited the relaxations, potentiated the contractile component and lowered the tone of the muscle.5 The relaxation and the tone were inhibited by papaverine (5 pg/ml) but the contractile component was unaffected. 6 It is suggested that potassium-induced relaxations are mediated through the activation of the sodium pump.

Mechanisms of intrinsic tone in bullfrog lung: relaxant effects of indomethacin, ouabain and potassium

“…This effect appears to result from stimulation of sodium-potassium ATPase, and is blocked by ouabain (Webb & Bohr, 1978;Webb, et al, 1981). Previous studies of potassium-induced relaxation of guinea-pig tracheal smooth muscle (Souhrada & Souhrada, 1981), and frog stomach muscle (Baysal et al, 1979) presumably involve this type of action because the relaxant effect was blocked by pretreatment with ouabain. This action, however, cannot explain all of the relaxant effects of potassium, since our studies show a marked relaxant effect even in the presence of ouabain.…”

Atropine‐resistant relaxation induced by high K+ in iris dilator muscle of the rat and pig

“…In some smooth muscle preparations, a small elevation of extracellular K+ concentration elicits a significant relaxation (Toda, 1976;Webb & Bohr, 1978;Baysal et al, 1979). Some of these relaxations have been explained by the contribution of the Na'-K' pump to muscular tone since ouabain, a specific inhibitor of Na'-K' ATPase, blocks the relaxation (Toda, 1976;Webb et al, 1981;Souhrada & Souhrada, 1981).…”