Komai H, Rusy B F
Can J Physiol Pharmacol. 1984 Nov;62(11):1382-6. doi: 10.1139/y84-230.
In rabbit papillary muscles, the pronounced inotropic effect of amrinone (0.4-0.8 mg/mL) observed at low stimulation frequencies (0.1-0.5 Hz) diminished as the frequency was increased to 1.0-2.0 Hz. Reversal of the negative inotropic effect of halothane (1%) by amrinone (0.8 mg/mL) was similarly dependent on stimulation frequency. The contractile response to paired-pulse stimulation in the presence of amrinone (0.8 mg/mL) was summation rather than postextrasystolic potentiation. Amrinone (0.8 mg/mL) was not effective in reversing the negative inotropic effect of halothane (1%) on potentiated state contraction generated by paired-pulse stimulation. These results suggest that amrinone increases the influx of extracellular Ca2+ across the sarcolemma but not the availability of cellular Ca2+ which accumulates, most likely in sarcoplasmic reticulum, under the condition of potentiation.
在兔乳头肌中，当刺激频率从低频率（0.1 - 0.5Hz）增加到1.0 - 2.0Hz时，氨力农（0.4 - 0.8mg/mL）在低刺激频率下所观察到的明显正性肌力作用减弱。氨力农（0.8mg/mL）对氟烷（1%）负性肌力作用的逆转同样依赖于刺激频率。在存在氨力农（0.8mg/mL）的情况下，对成对脉冲刺激的收缩反应是总和而不是期外收缩后增强。氨力农（0.8mg/mL）不能有效逆转氟烷（1%）对成对脉冲刺激产生的增强状态收缩的负性肌力作用。这些结果表明，氨力农增加了细胞外Ca2+跨肌膜的内流，但在增强状态下，最有可能在肌浆网中积累的细胞内Ca2+的可用性并未增加。
