Role of the endothelium on the response to adrenoceptor agonists of rabbit aorta during cooling

• DOI: 10.1111/j.1472-8206.2000.tb00390.x
• Publication Date: 2009-08-26T18:42:06Z
• Authors: Esra K. Ataik; Ayşe S. Şahin; Mehmet Kiliç; Necdet Doğan
• Keywords: Male; Xylazine; Nitric Oxide Synthase Type III; Aorta, Thoracic; In Vitro Techniques; Adrenergic Agonists; Clonidine; Methoxamine; Cold Temperature; Phenylephrine; 03 medical and health sciences; NG-Nitroarginine Methyl Ester; 0302 clinical medicine; Adrenergic alpha-2 Receptor Agonists; Animals; Adrenergic alpha-1 Receptor Agonists; Endothelium, Vascular; Rabbits; Enzyme Inhibitors; Nitric Oxide Synthase; Adrenergic alpha-Agonists; Muscle Contraction

Abstract— The role of the endothelium in the effects of cooling on the response to α1‐ and α2‐adrenoceptor agonists of rabbit aorta was studied. The contractions induced by clonidine (10−9‐ 3 × 10−4M) and xylazine (10−7‐ 10−3M) but not phenylephrine (10−9‐ 3 × 10−4M) and methoxamine (10−9‐ 3 × 10−4M) were enhanced in endothelium‐denuded or NG‐nitro‐L arginine methyl esther (l‐NAME) (10−5M) pretreated rabbit aorta. The senstivily, but not the maximal response, of both α1‐ and α2‐adrenoceptor agonists was significantly lower at 28 °C (cooling) than at 37 °C. Endothelium removal did not affect the action of cooling. These results were taken as evidence for the specificity of α2‐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 α1‐ and α2‐adrenoceptors.