Non-adrenergic, non-cholinergic innervation in monkey and human cerebral arteries.

1 Transmural electrical stimulation (0.5 to 20 Hz) and nicotine (10(-4) M) produced relaxations of helically-cut strips of monkey and human cerebral arteries, contracted with prostaglandin F2 alpha. 2 The relaxation induced by electrical stimulation was suppressed or abolished by tetrodotoxin, while the nicotine-induced relaxation was abolished by hexamethonium but was unaffected by tetrodotoxin. Both relaxation was abolished by hexamethonium but was unaffected by tetrodotoxin. Both relaxations were not attenuated by beta-adrenoceptor antagonists and atropine. 3 These findings may indicate that large cerebral arteries of the monkey and man are innervated by non-adrenergic, non-cholinergic nerves, excitation of which liberates unknown vasodilator substance(s).