Nitroglycerin-sensitive and -resistant contractions mediated by receptor-operated calcium channels in rabbit ear artery.
In isolated rabbit ear arteries incubated in a Ca2+-free medium with EGTA and nifedipine in the presence of norepinephrine, serotonin or histamine, an addition of Ca2+ induced a tonic contraction which is due to Ca2+ entry through receptor-operated Ca2+ channels (ROCs). Nitroglycerin (10(-4) M) significantly inhibited the ROCs-dependent contractions produced by serotonin or histamine, but failed to inhibit the ROCs-dependent contraction by norepinephrine. These results suggest the possible existence of two types of receptor-operated Ca2+ channels in rabbit ear artery.
D000818:Animals; D001158:Arteries / Q000187:drug effects; D004423:Ear / Q000098:blood supply; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D005996:Nitroglycerin / Q000494:pharmacology*; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology
D007473:Ion Channels; D012701:Serotonin; D006632:Histamine; D005996:Nitroglycerin