title: Endothelial modulation of resting and stimulated vascular tone in the pig capsular testicular artery.
abstract: We have investigated the wall tension characteristics and the role of endothelium on vascular tone, at rest and under K+ depolarization, in isolated rings from the pig capsular testicular artery. The active tension reached a maximum that was significantly lower in vessels without endothelium, whereas the passive tension and the Ca2+-dependent myogenic tone were not significantly affected by endothelium removal. Both NG-nitro-l-arginine (L-NOARG, 10(-4) M) and methylene blue (10(-5) M), increased the basal resting tension (BRT) in vessels with endothelium, while indomethacin (10(-6) M) decreased BRT in vessels both with and without endothelium. Either removal of endothelium or treatment with indomethacin (10(-6) M), quinacrine (10(-5) M) or ibuprofen (10(-5) M), significantly depressed the K+ concentration response curve, while dazoxiben (10(-5) M) and SQ 30,741 (10(-5) M) had no effect. L-NOARG (10(-6) M) potentiated the contractile response to K+ in vessels with endothelium, whereas L-NOARG (10(-4) M) was ineffective in vessels devoid of endothelium. These results suggest that a predominating NO release from endothelium, together with a cyclooxygenase-derived vasoconstrictor, modulate vascular tone at rest. In contrast, predominant endothelial release of a cyclooxygenase-derived contractile factor, but different from TXA2, PGH2 or superoxide anions, is induced by K+ depolarization and leads to vasoconstriction.
authors.affiliation: Departamento de Fisiología, Facultad de Veterinaria, Universidad Complutense, 28040-Madrid, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Costa
authors.forename: E
authors.initials: E
authors.lastname: Jimenez
authors.forename: A
authors.initials: A
authors.lastname: Labadía
authors.forename: A
authors.initials: A
authors.lastname: García-Pascual
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology; D015237:Dinoprost / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D019335:Nitroarginine / Q000494:pharmacology; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D013737:Testis / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects; D014666:Vasomotor System / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D019335:Nitroarginine; D015237:Dinoprost; D011188:Potassium; D008751:Methylene Blue; D007213:Indomethacin