Interference of pentobarbital and thiopental with the vascular contraction and noradrenaline release in human cerebral arteries

1. 1.|Thiopental and pentobarbital induced dose-dependent vasodilations in human cerebral arteries previously contracted with noradrenaline (NA), serotonin (5-HT) and KCl. Preincubation with both barbiturates decreased the contractions evoked by the three agents. 2. 2.|Pentobarbital and thiopental reduced the Ca 2+-induced contractile effects in K +-depolarized arteries and 5-HT-Ca 2+ and NA-Ca 2+ contractions dose-dependently. 3. 3.|The tritium release evoked by K + from these vessels prelabelled with [ 3H]NA was significantly reduced by both barbiturates at 10 −3M and by Ca 2+ removal. 4. 4.|These results indicate that pentobarbital and thiopental essentially produce a similar interference with Ca 2+ influx inhibiting the contractile responses induced by the three vasoactive agents and the exocytotic NA release evoked by K +.