Cui Y, Tan Y H
Zhongguo Yao Li Xue Bao. 1989 Jan;10(1):54-7.
The effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on the contractile response of electrically paced guinea pig papillary muscles in vitro were studied. I-65 (0.1-300 mumol/L) decreased the contractile force and inhibited isoprenaline-induced restoration of the contractile response in papillary muscles rendered inexcitable by KCl 22 mmol/L. Both effects were concentration-dependent, and the IC50 were 36.0 and 7.3 mumol/L, respectively. I-65 antagonized the positive inotropic effects of Iso and CaCl2 in a non-competitive manner. Like verapamil, I-65 had a frequency-dependent negative inotropic effect, and delayed the recovery of post-rest potentiation. It is concluded that the negative inotropic effect of I-65 results not only from the reduction of Ca2+-influx through the sarcolemmal membrane, but also from the inhibition of Ca2+ translocation in the sarcoplasmic reticulum.
研究了柠檬酸3,6 - 二甲氨基二苯并吡啶鎓（I - 65）对体外电刺激豚鼠乳头肌收缩反应的影响。I - 65（0.1 - 300 μmol/L）可降低收缩力，并抑制异丙肾上腺素诱导的由22 mmol/L氯化钾使乳头肌失去兴奋性后收缩反应的恢复。两种效应均呈浓度依赖性，IC50分别为36.0和7.3 μmol/L。I - 65以非竞争性方式拮抗异丙肾上腺素和氯化钙的正性肌力作用。与维拉帕米一样，I - 65具有频率依赖性负性肌力作用，并延迟了静息后增强的恢复。得出结论，I - 65的负性肌力作用不仅源于通过肌膜的钙内流减少，还源于对肌浆网中钙转运的抑制。
