Karliner J S, Alabaster C, Stephens H, Barnes P, Dollery C
Cardiovasc Res. 1981 May;15(5):296-304. doi: 10.1093/cvr/15.5.296.
To assess the possible relation between catecholamine responses and adrenoceptor affinity and density, we compared the effect of noradrenaline, isoprenaline and ouabain on the right ventricular muscle strips from normal and cardiomyopathic hamsters with alpha 1- and beta-adrenoceptor characteristics assessed by radioligand binding methods. At concentrations of 1.28, 2.56, 5.0 and 10 x 10 (-6) mol . litre (-1) noradrenaline raised isometric tension by 27 +/- 4, 39 +/- 5, 52 +/- 5 and 61 +/-6% in normal animals (n = 6). Corresponding increase of 65 +/- 8, 92 +/- 8, 109 +/- 9 and 115 +/- 10% occurred in cardiomyopathic hamsters (n=11, all P less than 0.02). The responses to isoprenaline (Emax =82%) and ouabain did not differ between the two groups of hamsters. [3H]-prazosin, a new radioligand, and [-3H]-dihydroalprenolol were used to assess alpha 1- and beta-adrenoceptors in cardiac membranes. By Scatchard analysis, the KD values for both ligands did not differ between normal and cardiomyopathic hamsters, but the maximum number of binding sites was higher in the myopathic group: 5.5 vs 3.9 fmol . mg [-1] protein for [3H]-prazosin and 27 vs 20 fmol . mg [-1] protein for [-3H]-dihydroalprenolol (both P less than 0.05). Histochemically, oxidative and glycolytic activity were normal but lysosomal acid phosphatase was high. Possible explanations for the raise response to noradrenaline in cardiomyopathic hamster include and increased concentration of noradrenaline in the synaptic cleft due to defective neuronal uptake and / or stimulation of an augmented population of alpha 1-(postsynaptic) adrenoceptors.
为了评估儿茶酚胺反应与肾上腺素能受体亲和力及密度之间的可能关系，我们比较了去甲肾上腺素、异丙肾上腺素和哇巴因对正常仓鼠和心肌病仓鼠右心室肌条的作用，并采用放射性配体结合法评估其α1和β肾上腺素能受体特性。在浓度为1.28、2.56、5.0和10×10（-6）mol·L（-1）时，去甲肾上腺素使正常动物（n = 6）的等长张力分别提高了27±4%、39±5%、52±5%和61±6%。在心肌病仓鼠（n = 11，所有P < 0.02）中，相应的增加分别为65±8%、92±8%、109±9%和115±10%。两组仓鼠对异丙肾上腺素（Emax = 82%）和哇巴因的反应没有差异。[3H] - 哌唑嗪（一种新的放射性配体）和[-3H] - 二氢心得舒被用于评估心肌膜中的α1和β肾上腺素能受体。通过Scatchard分析，两种配体的KD值在正常仓鼠和心肌病仓鼠之间没有差异，但结合位点的最大数量在病变组中更高：[3H] - 哌唑嗪为5.5对3.9 fmol·mg[-1]蛋白质，[-3H] - 二氢心得舒为27对20 fmol·mg[-1]蛋白质（两者P < 0.05）。组织化学检查显示，氧化和糖酵解活性正常，但溶酶体酸性磷酸酶较高。心肌病仓鼠对去甲肾上腺素反应增强的可能解释包括由于神经元摄取缺陷导致突触间隙中去甲肾上腺素浓度增加和/或对增多的α1（突触后）肾上腺素能受体的刺激。
