Muto Tatsuya, Hotta Yoshihiro, Miyazeki Kunihiro, Ando Hiroaki, Ishikawa Naohisa, Hasegawa Takaaki, Sugimoto Yumi, Yamada Jun, Miki Yasuyoshi
Department of Pharmacology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.
Mol Cell Biochem. 2005 Apr;272(1-2):119-32. doi: 10.1007/s11010-005-6909-0.
The protective effects of sarpogrelate (SG), a 5-HT2A antagonist, were investigated in perfused guinea-pig Langendorff hearts subjected to ischemia and reperfusion. Changes in cellular levels of high phosphorous energy, NO and Ca2+ in the heart together with simultaneous recordings of left ventricular developed pressure (LVDP) were monitored using an nitric oxide (NO) electrode, fluorometry and 31P-NMR. The recovery of LVDP from ischemia by reperfusion was 30.1% in the control, while the treatment with SG (5 x 10(-7) M) in pre- and post-ischemia hearts produced a gradual increase to 73.1 and 53.6%, respectively. At the final stage of ischemia, the intracellular concentration of Ca2+ ([Ca2+]i) and release of NO increased with no twitching and remained at a high steady level. The addition of SG increased the transient NO signal (TNO) level at the end of ischemia compared with the control, but [Ca2+]i during ischemia decreased. Meanwhile, mitochondrial Ca2+ uptake on acidification or Ca2+ content changes of the perfusate was suppressed by pre-treatment with SG or the KATP channel opener diazoxide, but not the KATP channel blocker 5-HD. The myocardial NO elevated with 5-HT in normal Langendorff hearts was suppressed by the treatment with SG. Therefore, the existence of the 5HT2A receptor in a Langendorff heart was anticipated. By in vitro EPR, SG was found to directly quench the hydroxy radical. Thus, these findings suggested that the 5-HT2A receptor induced in ischemia-reperfusion plays an important role in the mitochondrial KATP channel of hearts in close relation with NO and active oxygen radicals.
研究了5-羟色胺2A受体拮抗剂沙格雷酯（SG）对豚鼠离体Langendorff心脏缺血再灌注损伤的保护作用。采用一氧化氮（NO）电极、荧光法和31P-核磁共振技术，监测心脏中高能磷酸化合物、NO和Ca2+的细胞水平变化，并同步记录左心室舒张末压（LVDP）。对照组再灌注后LVDP的恢复率为30.1%，而缺血前后给予SG（5×10-7M）治疗，LVDP分别逐渐升高至73.1%和53.6%。在缺血末期，细胞内Ca2+浓度（[Ca2+]i）和NO释放增加，心脏无收缩，并维持在较高的稳定水平。与对照组相比，缺血末期加入SG可使瞬时NO信号（TNO）水平升高，但缺血期间[Ca2+]i降低。同时，SG预处理或KATP通道开放剂二氮嗪可抑制灌注液酸化时线粒体对Ca2+的摄取或Ca2+含量的变化，但KATP通道阻滞剂5-HD无此作用。SG可抑制正常Langendorff心脏中5-羟色胺引起的心肌NO升高。因此，推测Langendorff心脏中存在5HT2A受体。通过体外电子顺磁共振技术发现，SG可直接清除羟自由基。因此，这些研究结果提示，缺血再灌注诱导的5-HT2A受体在心脏线粒体KATP通道中起重要作用，且与NO和活性氧密切相关。
