Effects of organic and inorganic Ca(2+)-antagonists on acetylcholine-induced contraction in molluscan (Mytilus edulis) smooth muscle.
1. Effect of Ca(2+)-antagonist on the contractile response to acetylcholine (ACh) in molluscan (Mytilus edulis) smooth muscle was investigated. 2. ACh-induced contraction was remarkably reduced by exposure to Ca(2+)-deprived medium. 3. The organic Ca(2+)-blockers, verapamil, diltiazem and nicardipine, reduced the concentration-response curve for ACh in a concentration-dependent manner. 4. The inorganic Ca(2+)-blockers, MnCl2, NiCl2, CoCl2 and CdCl2, also reduced the concentration-response curve for ACh concentration-dependently. 5. ACh significantly increased the amounts of inositol 1,4,5-trisphosphate (IP3) in the ABRM. 6. ACh-induced contraction in the ABRM might therefore be mediated through an influx of extracellular Ca2+ and Ca(2+)-release from IP3 sensitive intracellular pools.
Miyahara
Y
Y
Department of Physiology and Anatomy, Nihon University College of Pharmacy, Chiba, Japan.
Kizawa
Y
Y
Sano
M
M
Murakami
H
H
D000109:Acetylcholine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D002118:Calcium / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism
D002121:Calcium Channel Blockers; D015544:Inositol 1,4,5-Trisphosphate; D000109:Acetylcholine; D002118:Calcium