Identification of myosin isoenzymes in rat cardiac muscle after long-term methamphetamine administration.

我们报道了长期服用甲基苯丙胺（MA）（其主要药理反应是从神经末梢释放儿茶酚胺）可引起大鼠心脏病变，如肥厚、肌溶解、收缩带坏死和肌纤维紊乱。为了进一步探讨MA致心脏损伤的机制，我们检测了心肌肌凝蛋白同工酶谱和肌动凝蛋白atp酶活性。给药1 mg/kg b. w. /天，连续8周和12周，心肌组织学检查显示心肌肥大、萎缩、肌溶解和肌纤维紊乱。根据Hoh等人的描述，在焦磷酸盐存在的情况下，用聚丙烯酰胺凝胶电泳研究了肌球蛋白的同工酶模式，并通过密度测定法进行了估计。注射等量生理盐水8 w和12 w的对照组的VI值有显著性差异（分别为69.3 +- 8.0%和56.2 +- 5.7%），但两组的对照组和MA处理的大鼠心脏之间无显著性差异。在10或0.1 ma Ca^<2+>存在下，Mg^2- atp酶活性用先前报道的方法测定。结果表明，8 w和12 w的对照组和各MA处理的大鼠在10muM Ca^<2+>处的Mg^<2+>- atp酶活性无显著差异，但12 w HA处理的大鼠在0.1muM Ca^<2+>处的Mg^<2+>- atp酶活性与对照组相比显著增加。结果提示，长期服用MA后，心肌功能和组织学均有一定改变。

We have reported that long-term administration of methamphetamine (MA) of which main pharmacologic reaction is releasing catecholamine from nerve endings induces rat cardiac lesions such as hypertrophy, myolysis, contraction band necrosis and disarray of myofibers. To further investigate the mechanism of MA induced cardiac injury we examined the myosin isozyme pattern and the actomyosin ATPase activity of the heart. The histological examination of r-at heart administered MA 1 mg/kg b. w. /day for 8 weeks and 12 weeks revealed hypertrophy, atrophy, myolysis and disarray of myofibers. Isozyme patterns of myosin were investigated by polyacrylamide gel electrophoresis in the presence of pyrophosphate as described by Hoh et al. and were estimated by densitometry. Though there was a significant difference between VI value of controls which were injected saline same volume for 8 w and 12 w (69.3 +- 8.0 % vs 56.2 +- 5.7 %, respectively), no significant difference was observed between controls and MA treated rat hearts in both groups. Mg^2-ATPase activity in the presence of 10 or 0.1muM Ca^<2+> were measured by previously reported method. In result, there were no significant differences in Mg^<2+>-ATPase activity at 10muM Ca^<2+> between 8 w and 12 w controls and each MA treated rats, but there was a significant increase of Mg^<2+>-ATPase activity at 0.1muM Ca^<2+> in 12 w HA treated rats compared with controls. The result suggest that there may be some changes in cardiac function after long-term MA administration as well as histologic changes.