Beca Sanja, Pavlov Evgeny, Kargacin Margaret E, Aschar-Sobbi Roozbeh, French Robert J, Kargacin Gary J
Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, T2N 4N1, Canada.
Pflugers Arch. 2008 Oct;457(1):121-35. doi: 10.1007/s00424-008-0510-9. Epub 2008 May 6.
Anion and cation channels present in the sarcoplasmic reticulum (SR) are believed to be necessary to maintain the electroneutrality of SR membrane during Ca(2+) uptake by the SR Ca(2+) pump (SERCA). Here we incorporated canine cardiac SR ion channels into lipid bilayers and studied the effects of tamoxifen and other antiestrogens on these channels. A Cl(-) channel was identified exhibiting multiple subconductance levels which could be divided into two primary conductance bands. Tamoxifen decreases the time the channel spends in its higher, voltage-sensitive band and the mean channel current. The lower, voltage-insensitive, conductance band is not affected by tamoxifen, nor is a K(+) channel present in the cardiac SR preparation. By examining SR Ca(2+) uptake, SERCA ATPase activity, and SR ion channels in the same preparation, we also estimated SERCA transport current, SR Cl(-) and K(+) currents, and the density of SERCA, Cl(-), and K(+) channels in cardiac SR membranes.
肌浆网（SR）中存在的阴离子和阳离子通道被认为是在SR钙泵（SERCA）摄取Ca(2+)期间维持SR膜电中性所必需的。在这里，我们将犬心脏SR离子通道整合到脂质双层中，并研究了他莫昔芬和其他抗雌激素对这些通道的影响。鉴定出一种Cl(-)通道，其表现出多个亚电导水平，可分为两个主要电导带。他莫昔芬减少了通道在其较高电压敏感带中停留的时间以及平均通道电流。较低的电压不敏感电导带不受他莫昔芬影响，心脏SR制剂中存在的K(+)通道也不受影响。通过检查同一制剂中的SR Ca(2+)摄取、SERCA ATP酶活性和SR离子通道，我们还估计了SERCA转运电流、SR Cl(-)和K(+)电流以及心脏SR膜中SERCA、Cl(-)和K(+)通道的密度。
