Role of the endothelium on the response to adrenoceptor agonists of rabbit aorta during cooling.
The role of the endothelium in the effects of cooling on the response to alpha1- and alpha2-adrenoceptor agonists of rabbit aorta was studied. The contractions induced by clonidine (10(-9)-3 x 10(-4) M) and xylazine (10(-7)-10(-3) M) but not phenylephrine (10(-9)-3 x 10(-4) M) and methoxamine (10(-9)-3 x 10(-4) M) were enhanced in endothelium-denuded or N(G)-nitro-L arginine methyl- ester (L-NAME) (10(-5) M) pretreated rabbit aorta. The sensitivity, but not the maximal response, of both alpha1- and alpha2-adrenoceptor agonists was significantly lower at 28 degrees C (cooling) than at 37 degrees C. Endothelium removal did not affect the action of cooling. These results were taken as evidence for the specificity of alpha2-adrenoceptor agonists on the production and release of nitric oxide from vascular endothelium. The results suggest that the endothelium seems to have no role in the cooling-induced responses of both alpha1- and alpha2-adrenoceptors.
Atalik
E K
EK
Department of Pharmacology, Faculty of Medicine, University of Selçuk, Konya, Turkey.
Sahin
A S
AS
Kiliç
M
M
Doğan
N
N
D000322:Adrenergic Agonists / Q000494:pharmacology*; D058646:Adrenergic alpha-1 Receptor Agonists; D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology*; D003000:Clonidine / Q000494:pharmacology; D003080:Cold Temperature; D004730:Endothelium, Vascular / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III; D010656:Phenylephrine / Q000494:pharmacology; D011817:Rabbits; D014991:Xylazine / Q000494:pharmacology
D000322:Adrenergic Agonists; D058646:Adrenergic alpha-1 Receptor Agonists; D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D004791:Enzyme Inhibitors; D010656:Phenylephrine; D014991:Xylazine; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D008729:Methoxamine; D003000:Clonidine; D019331:NG-Nitroarginine Methyl Ester