title: Membrane activation of smooth muscle from rabbit basilar artery by dopamine.
abstract: Intracellular membrane potential (EM) and force development were measured in rabbit basilar artery to help elucidate the mechanism of action of dopamine in this preparation. There was a strong correlation between membrane depolarization and contraction (r = 0.95) between 3 X 10-7 M to 10-4 M dopamine. When the vascular muscle cells were depolarized by elevating [K]0 there was a Em dependent decrease in force development in response to dopamine. Significant reduction of dopamine stimulated force development was observed when the vessel was depolarized by 5-6 mV by excess extracellular K+ and 90% inhibition was seen when the artery was depolarized to -20mV. When Ca++ influx was blocked, dopamine no longer induced force development. Such findings suggest that dopamine contracts rabbit basilar artery by a mechanism involving membrane depolarization. This process may involve an influx of extracellular Ca++ through voltage sensitive channels.
mesh_terms: D000818:Animals; D001488:Basilar Artery / Q000187:drug effects*; D004298:Dopamine / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011817:Rabbits
chemical_list: D004298:Dopamine