Regional differences in IK density in canine left ventricle: role of IK,s in electrical heterogeneity.
Regional differences in IK density in canine left ventricle: role of IK,s in electrical heterogeneity.
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犬左心室 IK 密度的区域差异：IK,s 在电异质性中的作用。
DOI：
10.1152/ajpheart.1995.268.2.h604
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Gintant,GA
中科院分区：
文献类型：
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作者：
Gintant,GA
用全细胞膜片钳技术研究了犬左心室心外膜和中层心肌细胞延迟整流钾电流（IK）。在3秒去极化脉冲至+25 mV期间，心外膜心肌细胞与中层心肌细胞相比，激活期间IK密度更大[1.06 +/-0.09 vs. 0.66 +/- 0.09 pA/pF（SE）; P < 0.01]。在所有检查时间（范围150 ms至3 s，+25 mV）和3 s测试脉冲终止时（电位+5至+65 mV），心外膜肌细胞的IK密度均较大。更大的IK密度不能解释激活动力学或电压依赖性激活的差异。已经在豚鼠肌细胞中描述了IK的两种组分（IK，r和IK，s）（Sanguinetti，M. C.的方法，和N. Jurkiewicz，J.Gen.Physiol.96：192-214，1990）。为了评估IK密度的差异是否可归因于IK，r或IK，s，将尾电流拟合为两个衰减指数的总和，每个分量类似于IK，s和IK，r，基于对E-4031的敏感性和整流特性。心外膜肌细胞中较大的尾电流密度是由于较大的IK，s，而IK，r无明显差异。这些结果表明，在左心室心外膜IK密度的区域差异是由于更大的IK，s成分，这有助于心室电异质性，并可能反映IsK通道的差异表达。
Delayed rectifier K+ current (IK) was studied in isolated myocytes from canine left ventricular epicardium and midmyocardium using whole cell patch-clamp techniques. IK density during activation was greater in epicardial vs. midmyocardial myocytes [1.06 +/- 0.09 vs. 0.66 +/- 0.09 pA/pF (SE); P < 0.01] measured during 3-s depolarizing pulses to +25 mV. IK density was greater in epicardial myocytes at all times examined (range 150 ms to 3 s, +25 mV) and on termination of 3-s test pulses (potentials +5 to +65 mV). Greater IK density could not be explained by differences in activation kinetics or voltage dependence of activation. Two components of IK (IK,r and IK,s) have been described in guinea pig myocytes (Sanguinetti, M. C., and N. Jurkiewicz, J. Gen. Physiol. 96: 192–214, 1990). To assess whether differences in IK density could be ascribed to IK,r or IK,s, tail currents were fit to the sum of two decaying exponentials, with each component analogous to IK,s and IK,r based on sensitivity to E-4031 and rectification properties. Greater tail current density in epicardial myocytes was due to greater IK,s with no discernible difference in IK,r. These results suggest that regional differences in IK density in left ventricular epicardium are due to a larger IK,s component, which contributes to ventricular electrical heterogeneity and may reflect the differential expression of the IsK channel.