Effect of pentobarbital on the reactivity of isolated human cerebral arteries.

The authors have analyzed the effect of pentobarbital (10(-5) M to 10(-3) M) on the contractile activity of isolated human cerebral arteries. Pentobarbital was found to inhibit both the spontaneous mechanical activity and the basal tone of these vessels. Relaxation induced by this drug was dose-dependent, and was more marked when the arterial tone was previously increased with noradrenalin, potassium chloride, or 5-hydroxytryptamine. In addition, pentobarbital inhibits, in a dose-dependent manner, the contractions elicited by these vasoconstrictor agents. The present findings indicate that barbiturates decrease cerebrovascular reactivity, and disagree with the hypothesis that these drugs reduce raised intracranial pressure by means of exerting a direct constrictive effect on the cerebral arteries.