Vynogradova O. The role of the endothelium in vasomotor reactions of the rat portal vein

The aim of this study was to investigate the role of endothelium in the vasoconstrictor tonic effects of neurohormonal factors using isolated rat portal vein. We have found that the tonic contractile responses of the portal vein induced by acetylcholine are partially due to the activation of receptors, located on smooth muscle cells of the vascular wall. It was shown that these responses were mediated both adrenergic receptors, in the presence of intact endothelium. The decisive role of endothelium in the catecholamines-induced increment of the portal vein tonic activity has been demonstrated for the first time, as well as certain differences in the mechanisms of the enhanced tonic activity of portal vein under adrenaline and noradrenaline treatment. The role of endothelium-derived prostaglandins and leukotrienes in contractile responses of portal vein to acetylcholine and noradrenaline has been demonstrated in healthy rats and rats with portal hypertension. The dose-dependent effect of serotonin on the contractile activity of the portal vein has also been demonstrated, and the role of the endothelium and adrenergic receptors in these responses has been investigated.