Ouabain-induced potentiation of Ca2+-contraction in the depolarized vas deferens of guinea-pig.
The effect of ouabain (10(-5) M) on the Ca2+-evoked phasic contraction was examined in various depolarized vas deferens of the guinea-pig. Ouabain-induced potentiation of the contraction occurred in muscle depolarized with 40 mM K+, but not in muscle depolarized with 0 mM or 137 mM K+. Furthermore, this potentiating effect of ouabain was investigated in the presence of Mn2+ and Mg2+, each of which has an inhibitory effect on Ca2+-contraction. It was strongly inhibited by Mn2+, but unaffected by Mg2+. From these findings it is suggested that ouabain facilitates Ca2+-entry, which is accompanied by the spike generation.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004357:Drug Synergism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects
D008345:Manganese; D010042:Ouabain; D008274:Magnesium; D011188:Potassium; D002118:Calcium