[Role of NO in the coronary vessel responses to agonists of various adrenoceptor subtypes].
We have studied the role of NO in coronary flow responses to agonists of alfa-2, beta-1, beta-2 and beta-3 adrenoceptors in the isolated mouse heart perfused according to the Langendorff method. The selective alfa-2 adrenoceptor agonist clonidine (10(-8) - 10(-6) M) displayed coronary vasoconstrictor properties as it induced dose-dependent decrease in the coronary flow. On the contrary, the nonselective beta-1/beta2/beta-3 adrenoceptor agonist isoprenaline (10(-8) - 10(-7) M) was a coronary vasodilator and caused dose-dependent increase in the coronary flow. The response to clonidine or isoprenaline was not changed by the presence of the NO-synthase inhibitor L-NO-nitroarginine methyl ester (L-NAME, 5 x 10(-4) M). The selective beta-3 adrenoceptor agonist BRL 37344 at high concentrations (10(-6) - 10(-5) M) produced a coronary vasodilator effect, but this effect was completely blocked by the beta-1/beta-2 adrenoceptor antagonist nadolol (10(-5) M). It is concluded that NO does not play any significant role in the coronary vascular responces mediated by alfa-2, beta-1, and beta-2 adrenoceptors in the isolated mouse heart. The functionally active beta-3 adrenoceptors seem to be not active in the coronary circulation in the isolated mouse heart.
Kozlovskiĭ
V I
VI
Zinchuk
V V
VV
Chlopicki
S
S
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D058665:Adrenergic beta-1 Receptor Agonists; D058666:Adrenergic beta-2 Receptor Agonists; D058667:Adrenergic beta-3 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000502:physiology*
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D058665:Adrenergic beta-1 Receptor Agonists; D058666:Adrenergic beta-2 Receptor Agonists; D058667:Adrenergic beta-3 Receptor Agonists; D000318:Adrenergic beta-Agonists; D009569:Nitric Oxide