Campbell I C, McKernan R M, Checkley S A, Glass I B, Thompson C, Shur E
Psychiatry Res. 1985 Jan;14(1):17-31. doi: 10.1016/0165-1781(85)90085-x.
The alpha-adrenoceptor on platelets has been characterized using 3H-yohimbine, 3H-dihydroergocriptine, and 3H-clonidine. The receptor, which exhibits the characteristics of an alpha 2-type, has a Bmax for dihydroergocriptine of 330 fmoles/mg protein, for yohimbine of 178 fmoles/mg protein, and for clonidine of 38 fmoles/mg protein. Clonidine, but not yohimbine binding, is decreased by the presence of K+, Na+, or Li+. Adenosine triphosphate (ATP) and the guanosine triphosphate (GTP) analogue, Gpp(NH)p, reduce the affinity of clonidine for its binding site. Acute exercise, such as playing squash, does not apparently alter the Bmax or Kd of 3H-yohimbine binding to platelet membranes, and in vitro studies, with intact platelets or platelet membranes, show that incubation with adrenalin (10 microM) does not induce alterations in Bmax or Kd. In the present study, no correlation was found between age and alpha 2-adrenoceptor numbers. There was no significant difference in the Bmax for 3H-yohimbine binding to platelet membranes from control and depressed subjects, although the mean value for the depressed group was some 10% lower than that for the corresponding control group. There were no overall significant and consistent effects of desipramine (DMI) treatment. After 2-3 days of treatment, the Bmax was reduced by 20%, after 7 days by 14%, and after 21 days it was 8% above the control value. When an additional group of patients on DMI (7 days of treatment) was analyzed using one supramaximal concentration of 3H-yohimbine, there was a significant decrease (25%) in binding.
已使用³H-育亨宾、³H-二氢麦角隐亭和³H-可乐定对血小板上的α-肾上腺素能受体进行了表征。该受体表现出α₂型的特征，二氢麦角隐亭的Bmax为330飞摩尔/毫克蛋白，育亨宾的Bmax为178飞摩尔/毫克蛋白，可乐定的Bmax为38飞摩尔/毫克蛋白。K⁺、Na⁺或Li⁺的存在会降低可乐定的结合，但不会降低育亨宾的结合。三磷酸腺苷（ATP）和鸟苷三磷酸（GTP）类似物Gpp(NH)p会降低可乐定与其结合位点的亲和力。急性运动，如打壁球，显然不会改变³H-育亨宾与血小板膜结合的Bmax或Kd，并且在完整血小板或血小板膜的体外研究表明，与肾上腺素（10微摩尔）孵育不会诱导Bmax或Kd的改变。在本研究中，未发现年龄与α₂-肾上腺素能受体数量之间存在相关性。³H-育亨宾与对照组和抑郁症患者血小板膜结合的Bmax没有显著差异，尽管抑郁症组的平均值比相应对照组低约10%。去甲丙咪嗪（DMI）治疗没有总体显著且一致的效果。治疗2 - 3天后，Bmax降低了20%，7天后降低了14%，21天后比对照值高8%。当使用一个超最大浓度的³H-育亨宾对另一组接受DMI治疗（7天）的患者进行分析时，结合有显著下降（25%）。
