Effect of presynaptic alpha-adrenoceptor blockade on responses to cardiac nerve stimulation in anesthetized dogs.
Phentolamine caused significant potentiation of chronotropic responses to cardioaccelerator nerve stimulation (CANS) in pentobarbital-anesthetized dogs without impairing neuronal reuptake of norepinephrine. In a separate group of dogs, desipramine produced slight augmentation of CANS responses which were potentiated further by phentolamine administration. These results provide support for the hypothesis that presynaptic alpha-adrenergic receptors play an inhibitory role in sympathetic neurotransmission and demonstrate that this mechanism is also functioning during stimulation of the cardioaccelerator nerve in pentobarbital-anesthetized dogs.
D000818:Animals; D003891:Desipramine / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006339:Heart Rate; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D010424:Pentobarbital; D010646:Phentolamine / Q000494:pharmacology; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000502:physiology*; D009435:Synaptic Transmission
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D010424:Pentobarbital; D003891:Desipramine; D009638:Norepinephrine; D010646:Phentolamine