Cooper P J, Lei M, Cheng L X, Kohl P
University Laboratory of Physiology, Oxford OX1 3PT, United Kingdom.
J Appl Physiol (1985). 2000 Nov;89(5):2099-104. doi: 10.1152/jappl.2000.89.5.2099.
Isolated, spontaneously beating rabbit sinoatrial node cells were subjected to longitudinal stretch, using carbon fibers attached to both ends of the cell. Their electrical behavior was studied simultaneously in current-clamp or voltage-clamp mode using the perforated patch configuration. Moderate stretch ( approximately 7%) caused an increase in spontaneous beating rate (by approximately 5%) and a reduction in maximum diastolic and systolic potentials (by approximately 2.5%), as seen in multicellular preparations. Mathematical modeling of the stretch intervention showed the experimental results to be compatible with stretch activation of cation nonselective ion channels, similar to those found in other cardiac cell populations. Voltage-clamp experiments validated the presence of a stretch-induced current component with a reversal potential near -11 mV. These data confirm, for the first time, that the positive chronotropic response of the heart to stretch is, at least in part, encoded on the level of individual sinoatrial node pacemaker cells; all reported data are in agreement with a major contribution of stretch-activated cation nonselective channels to this response.
使用连接在细胞两端的碳纤维对分离的、自发搏动的兔窦房结细胞进行纵向拉伸。采用穿孔膜片钳配置，在电流钳或电压钳模式下同时研究其电行为。适度拉伸（约7%）导致自发搏动频率增加（约5%），最大舒张电位和收缩电位降低（约2.5%），这与多细胞制剂中的情况一致。拉伸干预的数学模型表明，实验结果与阳离子非选择性离子通道的拉伸激活相符，类似于在其他心脏细胞群体中发现的情况。电压钳实验证实存在一种拉伸诱导电流成分，其反转电位接近 -11 mV。这些数据首次证实，心脏对拉伸的正性变时反应至少部分是在单个窦房结起搏细胞水平上编码的；所有报告的数据都与拉伸激活的阳离子非选择性通道对该反应的主要贡献一致。
