[Membrane mechanisms of the excitatory action of serotonin on the smooth muscles of the rabbit pulmonary artery].
Serotonin induced dose-dependent tonic contractions of the rabbit pulmonary artery smooth muscles with KED50, of 2.7 X 10(-7) mol/l. More than 80% of these contractions were found to be dependent on extracellular calcium. Hyperpolarization of cell membrane by inwardly applied electrical current caused nearly 50% reduction in serotonin-induced contractions. The same portion of contractions was inhibited by verapamil and Ca2+. Serotonin-, but not potassium-induced contractions were completely inhibited by sodium nitroprusside which is thought to be selective inhibitor of receptor-operated calcium channels. These findings could indicate that Ca2+ ions, responsible for serotonin-induced contractions enter the cell from the outer surface of the cellular membrane via receptor-operated calcium channels. Nearly half of serotonin-operated Ca2+ channels appear to be also potential-operated.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011651:Pulmonary Artery / Q000187:drug effects; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology*; D013268:Stimulation, Chemical
D007473:Ion Channels; D012701:Serotonin; D002118:Calcium
Issledovanie membrannykh mekhanizmov vozbuzhdaiushchego deĭstviia serotonina na gladkie myshtsy legochnoĭ arterii krolika.