title: Smooth muscle cells affect endothelial membrane potential in rat aorta.
abstract: The effects of vasoconstrictors on membrane potential of endothelium of intact rat aorta were investigated using the patch-clamp technique. Norepinephrine, endothelin (ET)-1, 5-hydroxytryptamine (5-HT), vasopressin, and angiotensin II evoked depolarization and oscillations in membrane potential. The alpha 1-adrenoreceptor agonist phenylephrine (PE), but not the alpha 2-agonist clonidine or the beta-agonist isoproterenol, evoked oscillations. The antagonist of 5-HT2-receptors, ketanserin, inhibited 5-HT-evoked oscillations. ET-3, unlike ET-1, did not evoke oscillations. The antagonists of voltage-operated Ca2+ channels, nifedipine and verapamil, inhibited vasoconstrictor-evoked oscillations, and the Ca2+ channel agonist BAY K 8644 enhanced oscillations. Acetylcholine and sodium nitroprusside inhibited PE-evoked oscillations. The inhibitors of NO synthase, N omega-nitro-L-arginine and NG-methyl-L-arginine, as well as methylene blue, enhanced oscillations. The intima of rat aorta with endothelium was removed from underlying smooth muscle. In this preparation, acetylcholine evoked a response similar to that in the intact vessel, but PE and ET-1 were without effect. These data suggest that vasoconstrictors acting on receptors on aortic smooth muscle evoke a response that is transferred to the endothelium and evokes depolarization and oscillations in endothelial membrane potential.
authors.affiliation: Physiological Laboratory, University of Cambridge, United Kingdom.
authors.forename: S M
authors.initials: SM
authors.lastname: Marchenko
authors.forename: S O
authors.initials: SO
authors.lastname: Sage
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009991:Oscillometry; D051381:Rats; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents