Altered alpha 1-adrenoceptor density and alpha 1A/alpha 1B ratio in rat hearts after propranolol treatment.
After rats were treated with propranolol (50 mg.kg-1, bid, ip) for 7 d, the density of alpha 1-adrenoceptors in the rat myocardial cell membranes increased from 137 +/- 25 to 178 +/- 30 fmol/mg protein determined by receptor radioligand assay. Whereas the KD value was not significantly changed, the relative proportion of alpha 1A-adrenoceptor subtype increased from 19 +/- 6 to 31 +/- 8%. The affinities of two subtypes to 5-methylurapidil were not obviously changed after propranolol treatment. It was suggested that alpha 1A-subtype was more important in alpha 1-receptor mediated alterations after beta-adrenoceptor blockade.
Zhang
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Y
Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing.
Hua
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Wang
X L
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D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology*; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification / Q000378:metabolism*
D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; C057446:5-methylurapidil; D011433:Propranolol; D011224:Prazosin