Amplifying Effects of Several Vasoconstrictor Agents of αi-Adrenoceptor-Mediated Contraction of Isolated Thoracic Aortae of the Guinea Pig

Publisher Website
Google Scholar
Abstract
In guinea-pig aorta phenylephrine and noradrenaline induced concentration-dependent contractions when β-adrenoceptors were blocked. The contractile response to phenylephrine was amplified by previous application of subthreshold concentrations of 5-hydroxytryptamine, ouabain, B-HT 920, Bay K 8644, phorbol-12-myristate-13-acetate and arachidonic acid. Bay K 8644 also enhanced the contractile response to noradrenaline. The amplification was not substantially altered by removing the endothelium of the aorta. The increase in cytosolic calcium availability induced by the vasoconstrictor agents investigated may be responsible for the enhancement of the α1-adrenoceptor-mediated contractions.