Alteration of the [Ca2+]i-force relationship during the vasorelaxation induced by a Ca2+ channel blocker SR33805 in the porcine coronary artery

摘要: The mechanism of vasorelaxation induced by SR33805 was investigated simultaneously monitoring the cytosolic Ca(2+) concentration ([Ca(2+)](i)) and force, determining level myosin light chain (MLC) phosphorylation in medial strip porcine coronary artery. inhibited sustained increases [Ca(2+)](i) force (IC(50); 3.2+/-1.0 49.4+/-27.5 nM, respectively) 118 mM K(+)-depolarization. There about a 10 fold difference inhibitory potency between force. completely elevation thromboxane A(2) analogue, U46619 histamine, at concentrations (1 microM) higher than those required for complete inhibition K(+)-depolarization elevation. had no effect on histamine or caffeine absence extracellular Ca(2+). caused leftward shift [Ca(2+)](i)-force relationship contraction cumulative application during MLC also shifted to left SR33805, while remained unaffected. In conclusion, an apparent relationship, accompanied greater degree given [Ca(2+)](i). this shift, however, still remains be elucidated.