蟾蜍心肌肾上腺素能受体的类型和含量

TYPE AND CONTENT OF ADRENOCEPTORS IN TOAD HEART

用放射配基结合分析法，研究了不同温度条件下蟾蜍心脏各部位肾上腺素能受体的类型和含量。结果表明，常温蟾蜍心肌膜在３７℃同β－受体的特异性标记配基＾３Ｈ－双氢心得舒（＾３Ｈ－ＤＨＡ）的最大结合（Ｂｍａｘ）及Ｋｄ值分别为：全赆，５５．１１±６．２２ｆｍｏｌ／ｍｇ蛋白及２．１５±０．４２ｎｍｏｌ／Ｌ；窦房，５５．８０±７．０３ｆｍｏｌ／ｍｇ蛋白及２．６５±０．３７ｎｍｏｌ／Ｌ；心室，５４．２７±３．

The type and content of adrenoceptors in heart of normothermic and cold-acclima-tized toad were studied by radioligand binding assay at different testing temperatures.The B_(max) and Kd values of membrane from normal toad heart binding to ~3H--DHA at37℃ were respectively 55.11±6.22 fmol/mg protein and 2.15±0.42 nmol/L forthe whole heart, 55.80±7.03 and 2.65±0.37 for sino--atrium and 54.27±3.06ed 1.84±0.14 for ventricle. While the binding to ~3H-DHE was very low and non-specific. When membrane from cold-acclimatized toad at 5--8℃ for 10 days was ex-amined for its binding to ~3H-DHA or ~3H-DHE at 10℃, the values of B_(max) and Kd wereas same as those of normothermic toad examined at 37℃. The present results suggestthat the toad heart is lacking of α-adrenoceptor, and the type and content of adrenocep-tors are not influenced by temperature.