Species differences in regulation of alpha-adrenergic receptor function.
The effects of alpha-adrenergic receptor stimulation with norepinephrine and phenylephrine after beta-adrenergic and muscarinic receptor blockades were compared in conscious baboons, calves, dogs, and rats in which left ventricular (LV) pressure. LV maximum rate of pressure development (dP/dt), and heart rate were measured. Autonomic receptor density was examined in crude sarcolemmal preparations from the hearts. The major physiological differences were observed in rats, where alpha 1-adrenergic receptor stimulation resulted in the greatest (P less than 0.05) increases in LV dP/dt (29 +/- 2%) in response to phenylephrine, 5.0 micrograms/kg, in comparison with responses in dogs (12 +/- 4%), calves (3 +/- 3%), and baboons (1 +/- 2%). This was associated with the greatest (P less than 0.05) alpha 1-adrenergic receptor density in the rat heart (73 +/- 5 fmol/mg) compared with values in the baboon (6 +/- 1 fmol/mg), calf (21 +/- 3 fmol/mg), or dog (10 +/- 3 fmol/mg) myocardium. Thus there are major differences among mammalian species in alpha-adrenergic receptor density and physiological responsiveness to alpha-adrenergic agonists.
Shen
Y T
YT
Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston.
Vatner
D E
DE
Gagnon
H E
HE
Vatner
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SF
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002417:Cattle; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D008566:Membranes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010215:Papio; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013045:Species Specificity
D000316:Adrenergic alpha-Agonists; D011942:Receptors, Adrenergic, alpha; D001285:Atropine; D011433:Propranolol