[Effects of the membrane potential level on serotonin-induced contraction of the pulmonary artery smooth muscle in rabbits].
The effects of changes in membrane potential level on the electrical and contractile responses induced by serotonin (10(-6) mol/l) were investigated in muscle strips from rabbit main pulmonary artery using sucrose-gap technique. In spite of the fact that serotonin-induced depolarization did not exceed the threshold level for development of contraction, it was followed by a strong tonic contraction. Nearly a half of this contraction could be relaxed by an electrotonic hyperpolarization of the membrane. A week preliminary depolarization of the muscle cells resulted in an increase while a strong depolarization--in dramatic decrease of serotonin-induced contraction. Nifedipine effectively blocked potassium-induced, but not serotonin induced contraction. We suggest that in addition to voltage-operated and receptor operated Ca channels in vascular smooth muscle cell membrane there is a separate class of nifedipine-insensitive Ca channels operated by both serotonin receptor and membrane potential.
Buryĭ
V A
VA
Gurkovskaia
A V
AV
Gokina
N I
NI
Shuba
M F
MF
D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D011651:Pulmonary Artery; D011817:Rabbits; D011985:Receptors, Serotonin / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*
D015220:Calcium Channels; D011985:Receptors, Serotonin; D012701:Serotonin; D009543:Nifedipine
Vliianie urovnia membrannogo potentsiala na vyzyvaemye serotoninom sokrashcheniia gladkikh myshts legochnoĭ arterii krolika.