The effect of potassium on frog stomach muscle.
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 micrograms/ml) blocked the relaxations and reversed them to contractions. The tension of strips was not affected. 4 Phenoxybenzamine (1 microgram/ml) and procaine (20 micrograms/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 micrograms/ml) but the contractile component was unaffected. 6 It is suggested that potassium-induced relaxations are mediated through the activation of the sodium pump.
D000818:Animals; D001001:Anura; D001693:Biological Transport, Active / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010208:Papaverine / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011343:Procaine / Q000494:pharmacology; D011893:Rana esculenta; D012964:Sodium / Q000378:metabolism; D013270:Stomach / Q000187:drug effects / Q000502:physiology*
D010643:Phenoxybenzamine; D011343:Procaine; D010042:Ouabain; D012964:Sodium; D010208:Papaverine; D011188:Potassium