Lefkowitz R J, Haber E
Proc Natl Acad Sci U S A. 1971 Aug;68(8):1773-7. doi: 10.1073/pnas.68.8.1773.
The 78,000 x g microsomal fraction of canine ventricular myocardium effected a 20-fold concentration of [(3)H]norepinephrine from a 10(-9) M solution. The [(3)H]norepinephrine bound was displaced by physiologic concentrations of the beta-adrenergic catecholamines isoproterenol, epinephrine, and norepinephrine, in that order, which is the order of effectiveness of their actions on the force and rate of cardiac contraction. Alpha-adrenergic compounds did not displace [(3)H]norepinephrine until concentrations four orders of magnitude greater were reached. The beta-adrenergic blocker propranolol displaced at 10(-6) M, whereas the alpha-adrenergic blocker phentolamine was inactive. Metabolites of the catecholamines did not compete for this binding site. It is concluded that, on the basis of specificity and affinity of binding, these microsomal particles are likely to contain the beta-adrenergic receptor.
犬心室肌78,000倍重力下的微粒体部分可使10⁻⁹M溶液中的[³H]去甲肾上腺素浓度提高20倍。结合的[³H]去甲肾上腺素被生理浓度的β-肾上腺素能儿茶酚胺异丙肾上腺素、肾上腺素和去甲肾上腺素依次取代，这与它们对心脏收缩力和速率的作用效果顺序一致。α-肾上腺素能化合物在达到大四倍数量级的浓度时才会取代[³H]去甲肾上腺素。β-肾上腺素能阻滞剂普萘洛尔在10⁻⁶M时产生取代作用，而α-肾上腺素能阻滞剂酚妥拉明则无活性。儿茶酚胺的代谢产物不会竞争该结合位点。基于结合的特异性和亲和力得出结论，这些微粒体颗粒可能含有β-肾上腺素能受体。
