Hatae J
Can J Physiol Pharmacol. 1986 Jul;64(7):927-30. doi: 10.1139/y86-159.
The effects of nicardipine, a new 1,4-dihydropyridine derivative, on electrical and mechanical properties of frog ventricular muscle were examined. Nicardipine (3 X 10(-7) M) reduced the twitch tension, and this reduction was frequency dependent, and considerable, in case of high frequencies. The resting potential was not affected by nicardipine (3 X 10(-7) M), but the plateau height of the action potential was decreased and the duration of the action potential was shortened. The suppression of this plateau height was frequency dependent. The nicardipine-induced suppression of tension and action potential could be almost completely antagonized by raising the concentration of [Ca]o or by applying isoprenaline (8 X 10(-7) M). These results suggest that the negative inotropic action of nicardipine is induced mainly by a reduction in the transmembrane Ca influx.
研究了新型1,4 - 二氢吡啶衍生物尼卡地平对蛙心室肌电和机械特性的影响。尼卡地平（3×10⁻⁷ M）降低了抽搐张力，且这种降低与频率相关，在高频情况下较为显著。静息电位不受尼卡地平（3×10⁻⁷ M）影响，但动作电位的平台期高度降低，动作电位持续时间缩短。这种平台期高度的抑制与频率相关。通过提高[Ca]o浓度或应用异丙肾上腺素（8×10⁻⁷ M），尼卡地平引起的张力和动作电位抑制几乎可被完全拮抗。这些结果表明，尼卡地平的负性肌力作用主要是由跨膜Ca内流减少所致。
