Studies on the location of catecholamine receptors in canine sympathetic ganglia.
Receptors mediating catecholamine-induced inhibition were studied in cardiac ganglia of pentobarbital-anesthetized dogs. Using selective agonists and antagonists the presence of three receptor subtypes was verified: alpha 1- and alpha 2-adrenoceptors and dopamine D2 receptors. Activation of alpha 1-adrenoceptors or dopamine D2 receptors reduced the response to preganglionic nerve stimulation but not to direct stimulation of the nicotinic acetylcholine receptors of the principal ganglion cells: response to both types of stimulation were reduced by activation of ganglionic alpha 2-adrenoceptors. These results suggested that two inhibitory systems were present in canine sympathetic ganglia and mediated the effects of exogenous catecholamines. One system involved alpha 1-adrenoceptors and dopamine D2 receptors located proximal to the synapse of the pre- and postganglionic neurons and the other involved alpha 2-adrenoceptors located distal to the intraganglionic synapse.
Department of Pharmacological, University of Chicago, IL 60612.
P T
PT
Horn
J D
JD
Kohli
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D005728:Ganglia, Sympathetic / Q000737:chemistry* / Q000187:drug effects; D006321:Heart / Q000294:innervation; D011942:Receptors, Adrenergic, alpha / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D017448:Receptors, Dopamine D2; D004246:Dimethylphenylpiperazinium Iodide