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.

No abstract

Intravenous levosimendan treatment was found effective by increasing the pathological luminal area and reducing muscular wall thickness measurements. This is the first study to show that intravenous administration of levosimendan is effective in preventing cerebral vasospasm induced by SAH in rabbits.