Le Grand B, Deroubaix E, Coulombe A, Coraboeuf E
Laboratoire de Physiologie Comparée, Université de Paris Sud, Orsay, France.
Am J Physiol. 1990 May;258(5 Pt 2):H1620-3. doi: 10.1152/ajpheart.1990.258.5.H1620.
The effect of 10(-6) M ouabain on macroscopic low-threshold T-type Ca2+ and high-threshold L-type Ca2+ currents was studied by whole cell recording in isolated guinea pig ventricular myocytes superfused with K-free, Na-free media, i.e., after suppression of Na-K-ATPase activity and Na influx through the Na-Ca exchanger. Under such conditions, the amplitudes of the two currents were significantly increased by ouabain. In particular, the current occurring in the -50 to -20 mV range (T-type Ca2+) was increased two- to threefold by ouabain and suppressed by 40 microM Ni2+. Ouabain shifted by approximately 10 mV toward negative potentials the steady-state inactivation curve of the T-type Ca2+ current but not that of the L-type Ca2+ current. It is concluded that ouabain enhances not only L-type Ca2+ current but also T-type Ca2+ current possibly through different mechanisms.
在无钾、无钠培养基中灌流的豚鼠离体心室肌细胞中，通过全细胞记录研究了10(-6)M哇巴因对宏观低阈值T型Ca2+电流和高阈值L型Ca2+电流的影响，即在抑制钠钾ATP酶活性和通过钠钙交换体的钠内流之后。在这种条件下，哇巴因使两种电流的幅度显著增加。特别是，在-50至-20mV范围内出现的电流（T型Ca2+）被哇巴因增加了两到三倍，并被40μM Ni2+抑制。哇巴因使T型Ca2+电流的稳态失活曲线向负电位方向移动约10mV，但不影响L型Ca2+电流的稳态失活曲线。得出的结论是，哇巴因可能通过不同机制不仅增强L型Ca2+电流，还增强T型Ca2+电流。
