Department of Evolutionary and Functional Biology, Physiology Section, University of Parma, 43124 Parma, Italy.
IEEE Trans Biomed Eng. 2012 Jan;59(1):226-33. doi: 10.1109/TBME.2011.2170987. Epub 2011 Oct 10.
Scaling of action potential (AP) duration (APD) in mammals of different size is a rather complex phenomenon, dominated by a regulatory type mechanism of ion channels expression. By means of simulations performed on six published mathematical models of cardiac ventricular APs of different mammals, it is shown that AP repolarization is autoregenerative in its later phase (ARRP) and that the duration of such phase scales linearly with APD. For each AP, a 3-D instantaneous time-voltage-current surface is constructed, which has been recently described in a more simplified model. This representation allows us to measure ARRP and to study the contribution to it for different ion currents. It has been found that the existence of an ARRP is not intrinsic to cardiac models formulation; one out of the six models does not show this phase. A linear correlation between ARRP duration and APD in the remaining models is also found. It is shown that ARRP neither simply depend on AP shape nor on APD. Though I(K1) current seems to be the main responsible for determining and modulating this phase, the mechanism by which ARRP scales linearly with APD remains unclear and raises further questions on the scaling strategies of cardiac repolarization in mammals.
不同大小哺乳动物的动作电位（AP）持续时间（APD）的缩放是一个相当复杂的现象，主要由离子通道表达的调节机制主导。通过对六种不同哺乳动物的心脏心室 AP 的已发表数学模型进行模拟，结果表明 AP 的复极化在后期具有自再生性（ARRP），并且该阶段的持续时间与 APD 呈线性缩放。对于每个 AP，构建了一个 3-D 瞬时时电压电流表面，最近在一个更简化的模型中对其进行了描述。这种表示方法允许我们测量 ARRP，并研究不同离子电流对其的贡献。结果发现，ARRP 的存在并不是心脏模型公式的内在特征；六个模型中有一个没有显示这个阶段。在其余的模型中也发现了 ARRP 持续时间与 APD 之间的线性相关性。结果表明，ARRP 既不单纯取决于 AP 形状，也不单纯取决于 APD。虽然 I(K1)电流似乎是决定和调节这个阶段的主要因素，但 ARRP 与 APD 呈线性缩放的机制尚不清楚，这引发了关于哺乳动物心脏复极化缩放策略的进一步问题。
