title: Prejunctional receptors in human digital arteries.
abstract: A human digital artery preparation obtained postmortem has been used to study factors influencing 3H-norepinephrine release evoked by periarterial nerve stimulation. Tetrodotoxin nearly abolished the stimulation-induced tritium outflow and the associated vasoconstrictor response. Increasing the frequency of stimulation from 1 to 6 Hz (constant number of 480 pulses) markedly enhanced the stimulation-induced tritium outflow per pulse. Cocaine only modestly increased the outflow. Phentolamine considerably increased, and clonidine significantly decreased, the stimulation-induced tritium outflow, thus indicating the presence of presynaptic alpha-adrenoceptors. Angiotensin also considerably enhanced the stimulation-induced tritium outflow. The results suggest that both frequency of stimulation and presynaptic receptors are of major importance in determining neurotransmitter release in the peripheral vasculature in man.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D001158:Arteries / Q000294:innervation; D003000:Clonidine / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology; D005385:Fingers / Q000098:blood supply*; D006801:Humans; D018377:Neurotransmitter Agents / Q000502:physiology; D010646:Phentolamine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium
chemical_list: D018377:Neurotransmitter Agents; D014316:Tritium; D000804:Angiotensin II; D013779:Tetrodotoxin; D003042:Cocaine; D003000:Clonidine; D010646:Phentolamine