通过[125I]-碘吲哚洛尔放射性配体结合试验测定围产期大鼠肝脏β-肾上腺素能受体的特征。

Characterization of rat liver beta-adrenoceptors during perinatal development as determined by [125I]-iodopindolol radioligand binding assays.

作者信息

Snell K, Evans C A

机构信息

Department of Biochemistry, University of Surrey, Guildford.

出版信息

Br J Pharmacol. 1988 Apr;93(4):817-26. doi: 10.1111/j.1476-5381.1988.tb11467.x.

DOI:10.1111/j.1476-5381.1988.tb11467.x

PMID:2839263

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1853877/

Abstract

The subtype specificity of beta-adrenoceptors in foetal (20 days post coitum) rat liver membrane preparations has been determined by use of [125I]-iodopindolol binding assays and the characteristics of radioligand binding have been resolved. 2. The kinetics of radioligand association and dissociation (in the presence of 5 x 10(-4) M isoprenaline) showed an association rate constant of 1.5 x 10(7) M-1 S-1 and dissociation rate constant of 9.1 x 10(-4) S-1, corresponding to a dissociation constant for [125I]-iodopindolol of 60.7 pM. A similar dissociation constant (75 pM) was determined by saturation binding assays. 3. The rank order of potency for displacement of [125I]-iodopindolol binding was consistent with binding to a predominantly beta 2-adrenoceptor population (i.e. ICI 118551 greater than isoprenaline greater than adrenaline greater than noradrenaline greater than atenolol). Computer analysis of displacement curves in the presence of a beta 1-subtype selective agent (atenolol) or a beta 2-subtype selective agent (ICI 118551) revealed the presence of beta 2- and beta 1-adrenoceptor subtypes in a ratio of about 80:20%. 4. Saturation binding assays by use of [125I]-iodopindolol were carried out at different perinatal ages to determine total beta-adrenoceptor concentrations and beta 2-subtype (in the presence of 5 x 10(-7) M atenolol) adrenoceptor concentrations. Competition binding assays with atenolol confirmed that at all ages apparent beta 2-adrenoceptor binding accounted for 84-95% of the total beta-adrenoceptor binding. The total beta- and beta 2-adrenoceptor binding capacity increased by 2.3 fold from 20 days post coitum to birth, and then decreased postnatally at 1 and 2 days post partum. The dissociation constant for [125I]-iodopindolol binding did not show any change with age. 5. The change in beta 2-adrenoceptor concentration with age is discussed in relation to the changing beta-adrenoceptor-mediated responsiveness of glucose production by rat liver during perinatal development.

摘要

通过使用[125I] - 碘吲哚洛尔结合试验，已确定胎鼠（受孕后20天）肝膜制剂中β - 肾上腺素能受体的亚型特异性，并解析了放射性配体结合的特性。2. 放射性配体结合和解离的动力学（在5×10（-4）M异丙肾上腺素存在下）显示结合速率常数为1.5×10（7）M - 1 S - 1，解离速率常数为9.1×10（-4）S - 1，对应于[125I] - 碘吲哚洛尔的解离常数为60.7 pM。通过饱和结合试验确定了类似的解离常数（75 pM）。3. [125I] - 碘吲哚洛尔结合置换的效力等级顺序与主要结合β2 - 肾上腺素能受体群体一致（即ICI 118551＞异丙肾上腺素＞肾上腺素＞去甲肾上腺素＞阿替洛尔）。在存在β1亚型选择性剂（阿替洛尔）或β2亚型选择性剂（ICI 118551）的情况下对置换曲线进行计算机分析，揭示β2 - 和β1 - 肾上腺素能受体亚型的比例约为80:20％。4. 使用[125I] - 碘吲哚洛尔在不同围产期进行饱和结合试验，以确定总β - 肾上腺素能受体浓度和β2亚型（在5×10（-7）M阿替洛尔存在下）肾上腺素能受体浓度。用阿替洛尔进行的竞争结合试验证实，在所有年龄段，表观β2 - 肾上腺素能受体结合占总β - 肾上腺素能受体结合的84 - 95％。总β - 和β2 - 肾上腺素能受体结合能力从受孕后20天到出生增加了2.3倍，然后在产后第1天和第2天下降。[125I] - 碘吲哚洛尔结合的解离常数未显示随年龄有任何变化。5. 讨论了β2 - 肾上腺素能受体浓度随年龄的变化与围产期发育期间大鼠肝脏中β - 肾上腺素能受体介导的葡萄糖生成反应性变化的关系。