[Experimental studies of the effect of diltiazem (Ca-antagonist) on cerebral circulation and cerebral arterial spasm].

Polygraphycal studies were carried out in order to evaluate the effects of Diltiazem (Ca-antagonist) on cerebral circulation in cats. In addition to these studies, the inhibitory effect of Diltiazem on incubated blood-, and serotonin-induced vasocontraction of basilar arteries was observed through on operating microscope. Experimental vasospasm were induced by local administration of incubated blood and 10(-5)--10(-6) M serotonin solution. The required dose of Diltiazem, 30-300 micrograms/kg, was injected by one shot intravenously. CBF slightly decreased concomitantly with transiently decreased blood pressure shortly after intravenous injection of Diltiazem. After that, CBF increased for 15-20 minutes and returned to the state similar to that before the administration of Diltiazem. The changes in reactive pattern of CBF depend on the doses of Diltiazem and related to changes of CAR and VAR which were thought to indicate the blood of cardiac output. Vasocontraction induced by incubated blood and serotonin was released 30-35 per cent for 30 minutes after intravenous injection of Diltiazem 100 micrograms/kg. However, by administration of Diltiazem before and after local application of incubated blood and serotonin on basilar arteries, vasocontraction was inhibited completely. These data suggest that administration of Diltiazem (Ca-antagonist) might be useful in the prophylaxis and treatment of vasospasm following rupture of cerebral aneurysm.