Alvarez J L, Vassort G
Laboratorio de Electrofisiologia, Instituto de Cardiologia y Cirugia Cardiovascular, La Habana, Cuba.
J Mol Cell Cardiol. 1991 May;23(5):627-38. doi: 10.1016/0022-2828(91)90054-p.
The effects of N-n-propylajmaline (prajmalium) on the Na and Ca currents of single frog atrial and ventricular cells were studied by means of the whole-cell patch-clamp technique. Prajmalium (10(-9) to 10(-6) M) depressed the Na current (INa) in a dose- and use-dependent manner. In the same range of concentrations, prajmalium induced a dual effect on the high (ICaL) and low (ICaT) threshold Ca currents (the latter being only present in atrial cells). At a low concentration (10(-9) M), prajmalium increased both Ca currents while at high concentrations (10(-6) M) it depressed them. Prajmalium appeared very potent on ICaT although this current is generally reported to be barely sensitive to agonists and drugs. The action of the drug was also accompanied by a shortening in the half-time of inactivation of the Ca currents and a slight hyperpolarizing shift of their availability curves. The increase in ICaL by prajmalium was not prevented by prazosin (10(-7) M) nor by propranolol (10(-6) M), and it was also observed after ICaL had been fully stimulated by isoproterenol (10(-7)M). Nifedipine (10(-6) M), however, was able to prevent or block the prajmalium-induced increase in ICaL. Some similarities between the actions of prajmalium and dihydropyridine agonists on Ca currents are discussed.
采用全细胞膜片钳技术研究了N - 正丙基阿马林（普拉马林）对单个蛙心房和心室细胞钠电流和钙电流的影响。普拉马林（10^(-9)至10^(-6) M）以剂量和使用依赖性方式抑制钠电流（INa）。在相同浓度范围内，普拉马林对高阈值（ICaL）和低阈值（ICaT）钙电流产生双重作用（后者仅存在于心房细胞中）。在低浓度（10^(-9) M）时，普拉马林增加两种钙电流，而在高浓度（10^(-6) M）时则抑制它们。普拉马林对ICaT似乎非常有效，尽管一般报道该电流对激动剂和药物几乎不敏感。药物的作用还伴随着钙电流失活半衰期的缩短及其可用性曲线的轻微超极化偏移。普拉马林引起的ICaL增加不受哌唑嗪（10^(-7) M）或普萘洛尔（10^(-6) M）的阻止，并且在ICaL已被异丙肾上腺素（10^(-7) M）完全刺激后也观察到这种增加。然而，硝苯地平（10^(-6) M）能够阻止或阻断普拉马林诱导的ICaL增加。讨论了普拉马林和二氢吡啶激动剂对钙电流作用之间的一些相似性。
