Effect of pentobarbital on the noradrenaline release induced by drugs and field electrical stimulation from cerebral and femoral arteries of the cat

The present studies showed that field electrical stimulation, high potassium (K⁺), tyramine and ionophore X537A induced tritium release from cerebral and femoral arteries of cat prelabelled with [³H]noradrenaline. The secretion caused by K⁺ or field stimulation was Ca²⁺-dependent and was antagonized by high concentrations of pentobarbital (10^?4 and 10^?3M), whereas that induced by the rest of the drugs was unchanged in the same situations. The noradrenaline uptake by these arteries was reduced by pentobarbital (10^?3M and 10^?4M). These results suggest that this barbiturate interferes with Ca²⁺ entry to the adrenergic nerve endings, and therefore antagonizes the noradrenaline release by Ca²⁺-dependent processes (exocytosis).