Coulombe A, Lefevre I A, Deroubaix E, Thuringer D, Coraboeuf E
Laboratoire de Physiologie Comparée associé au CNRS (URA 1121), Université Paris-Sud, Orsay, France.
J Mol Cell Cardiol. 1990 Aug;22(8):921-32. doi: 10.1016/0022-2828(90)90123-j.
The effect of 2,3-butanedione 2-monoxime (BDM), a substance possessing phosphatase-like activity, was studied on action potentials of isolated rat heart and on the slow inward calcium current and outward current (including the 4-aminopyridine (4-AP)-sensitive transient outward component), in rat ventricular myocytes. In contrast to what was observed by other authors in different species and cardiac tissues, BDM increased markedly the amplitude and duration of the rat ventricular action potential plateau. On the other hand, in the presence of 4-AP and ryanodine BDM shortened action potential duration. BDM decreased in a dose dependent manner the amplitude of both the slow inward calcium current and the transient outward current, accelerated their inactivation and shifted their steady-state inactivation-voltage relationships towards negative potentials. BDM also depressed other components of outward current. It is suggested that the lengthening effect of BDM on action potential duration results mainly from the simultaneous reduction of both the slow inward calcium current and the transient outward current, two antagonistic currents with unequal influences on action potential plateau development. The similarity of effect of BDM on these two currents also suggests that ionic channels generating them might require similar phosphorylation for their functioning.
研究了具有磷酸酶样活性的物质2,3-丁二酮单肟（BDM）对离体大鼠心脏动作电位以及大鼠心室肌细胞慢内向钙电流和外向电流（包括对4-氨基吡啶（4-AP）敏感的瞬时外向成分）的影响。与其他作者在不同物种和心脏组织中观察到的情况相反，BDM显著增加了大鼠心室动作电位平台期的幅度和持续时间。另一方面，在存在4-AP和ryanodine的情况下，BDM缩短了动作电位持续时间。BDM以剂量依赖的方式降低了慢内向钙电流和瞬时外向电流的幅度，加速了它们的失活，并使它们的稳态失活-电压关系向负电位方向移动。BDM还抑制了外向电流的其他成分。有人提出，BDM对动作电位持续时间的延长作用主要源于慢内向钙电流和瞬时外向电流同时减少，这两种拮抗电流对动作电位平台期发展的影响不相等。BDM对这两种电流的作用相似性也表明，产生它们的离子通道在功能上可能需要相似的磷酸化作用。
