Postjunctional alpha-1 and alpha-2 adrenoceptors in the coronaries of the perfused guinea-pig heart.
Prazosin and yohimbine were used to differentiate postjunctional alpha adrenoceptors in the coronaries of the perfused guinea-pig heart. Two postjunctional alpha adrenoceptor subtypes were distinguished by the affinities of the receptor for yohimbine and prazosin. The pA2 for yohimbine were 8.74 against alpha-methylnorepinephrine and 8.98 against BHT-920, and the pA2 for prazosin was 9.84 against phenylephrine. Yohimbine was not very active against the alpha-1 selective agonist as was prazosin against the alpha-2 selective agonists. Alpha-1 and alpha-2 postjunctional adrenoceptors mediate vasoconstriction in the whole coronary bed of the perfused guinea-pig heart.
Decker
N
N
Schwartz
J
J
D000818:Animals; D001381:Azepines / Q000378:metabolism; D003000:Clonidine / Q000378:metabolism; D003331:Coronary Vessels / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D008771:Nordefrin / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D010477:Perfusion; D010656:Phenylephrine / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014655:Vascular Resistance; D015016:Yohimbine / Q000378:metabolism
D001381:Azepines; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D015016:Yohimbine; C024763:talipexole; D003000:Clonidine; D008771:Nordefrin; D009638:Norepinephrine; D011224:Prazosin