[Effect of serotonin and histamine on the cellular contractile activity of the internal carotid artery].

In the experiments on isolated segments of the canine internal carotid artery it was shown that serotonin (5.10(-11)--5.10(-5) g/ml) activated the contractions. Histamine (5.10(-9) g/ml) induced dilation of isolated segments and its higher concentrations produced the contractile responses. Serotonin and histamine were shown to induce the contractions of the depolarized smooth vascular muscle. It is suggested that serotonin activates the inflow of extracellular calcium ions and histamine activates both the inflow of extracellular and the cut-flow of the intracellular calcium ions.