Mechanism of the indirect adrenergic effect of histamine in cat cerebral arteries.
KCl (50 mM), tyramine (10(-7) M), and histamine (10(-4) M) induced an increase in tritium release from cat cerebral arteries preincubated with [3H]noradrenaline, this increase being due in part to noradrenaline. When calcium was absent from the superfusion medium, only tyramine (10(-7) M) enhanced the tritium outflow. Colchicine (10(-3) M) partially inhibited the increase in radioactivity brought about by 10(-4) M histamine. KCl (50 mM) also evoked release of radioactivity from cerebral arteries preloaded with [3H]histamine; this release was unaffected by reserpine pretreatment or removal of both superior cervical sympathetic ganglia. Neither tyramine (10(-7) M) nor compound 48/80 (300 micrograms ml-1) altered the spontaneous tritium outflow from cerebral blood vessels preincubated with [3H]histamine. These results suggest that histamine is not accumulated by sympathetic nerve endings and elicits its noradrenaline-releasing effect by means of an exocytotic process.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002415:Cats; D002536:Cerebral Arteries / Q000187:drug effects* / Q000294:innervation; D003078:Colchicine / Q000494:pharmacology; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects*; D014439:Tyramine / Q000494:pharmacology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
D003189:p-Methoxy-N-methylphenethylamine; D011189:Potassium Chloride; D006632:Histamine; D012110:Reserpine; D003078:Colchicine; D002118:Calcium; D009638:Norepinephrine; D014439:Tyramine