Binding of [3H]befunolol to beta-adrenoceptors in cardiac muscles of fetal and neonatal rat.
Characterization of beta-adrenoceptors was studied in heart muscles of rat fetus and neonate. The results of binding assay with [3H]befunolol, a beta-adrenergic partial agonist, to membrane fractions from rat heart muscles indicate that beta-adrenoceptors contain two different affinity sites. In the presence of 5'-guanylylimidodiphosphate, the low affinity site was reduced, while the high affinity site was not affected. The dissociation constants for both sites did not change during pre- and post-natal development. But the maximum binding sites for both sites decreased slightly but significantly (p less than 0.05) during development. A 10-fold decrease in norepinephrine sensitivity and isoprenaline sensitivity during pre- and post-natal development was not explained by the slight decrease in the maximum binding sites.
Koike
K
K
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Tanaka
H
H
Shigenobu
K
K
Takayanagi
I
I
D000319:Adrenergic beta-Antagonists / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D008861:Microsomes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D011247:Pregnancy; D011412:Propanolamines / Q000378:metabolism*; D051381:Rats
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D006165:Guanylyl Imidodiphosphate; C006034:befunolol