Akaishi Y, Hattori Y, Kanno M, Sakuma I, Kitabatake A
Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan.
Res Commun Mol Pathol Pharmacol. 1994 Aug;85(2):171-9.
The influence of pretreatment with pertussis toxin (PTX) on characteristics of beta-adrenoceptor bindings was examined in myocardial ventricular membranes prepared from rabbits which received an intravenous injection of PTX (10 micrograms/kg) or its vehicle. The density and affinity of beta-adrenoceptors assessed by (-)-[125I]iodocyanopindolol were not significantly altered by PTX pretreatment. However, a fraction of agonist binding sites with high affinity significantly increased in PTX-pretreated myocardial membranes. In the presence of 100 microM 5'-guanylyl imidodiphosphate, all agonist binding sites were converted to low-affinity sites in both control and PTX-pretreated membranes. The results suggest that Gi might regulate negatively coupling of beta-adrenoceptors to Gs.
在接受静脉注射百日咳毒素（PTX，10微克/千克）或其赋形剂的家兔制备的心肌心室膜中，研究了百日咳毒素预处理对β-肾上腺素能受体结合特性的影响。用（-）-[125I]碘氰吲哚洛尔评估的β-肾上腺素能受体的密度和亲和力，并未因PTX预处理而发生显著改变。然而，在PTX预处理的心肌膜中，具有高亲和力的一部分激动剂结合位点显著增加。在存在100微摩尔5'-鸟苷酰亚胺二磷酸的情况下，对照膜和PTX预处理膜中的所有激动剂结合位点均转变为低亲和力位点。结果表明，Gi可能对β-肾上腺素能受体与Gs的负向偶联起调节作用。
