Ranki H J, Budas G R, Crawford R M, Jovanović A
Tayside Institute of Child Health, Ninewells Hospital & Medical School, University of Dundee, Dundee, Scotland, United Kingdom.
J Am Coll Cardiol. 2001 Sep;38(3):906-15. doi: 10.1016/s0735-1097(01)01428-0.
The main objective of this study was to establish whether gender regulates expression and/or properties of cardiac ATP-sensitive K(+) (K(ATP)) channels.
Recently, evidence has been provided that differing cardiac responses in males and females to metabolic stress may result from gender-specific difference(s) in the efficiency of endogenous cardioprotective mechanism(s) such as K(ATP) channels.
A reverse transcription polymerase chain reaction (RT-PCR) using primers specific for Kir6.2, Kir6.1 and SUR2A subunits was performed on total RNA from guinea pig ventricular tissue. Western blotting using anti-Kir6.2 and anti-SUR2A antibodies was performed on cardiac membrane fraction. Whole-cell, single-channel electrophysiology and digital epifluorescent Ca(2+) imaging were performed on isolated guinea pig ventricular cardiomyocytes.
The RT-PCR revealed higher levels of SUR2A, but not Kir6.1 and Kir6.2, messenger RNA in female tissue relative to male tissue, while much higher levels of both Kir6.2 and SUR2A proteins in cardiac membrane fraction in female tissue compared with male tissue were found. In both male and female tissue, pinacidil (100 microM), a K(ATP) channel opener, induced outward whole-cell currents. The current density of the pinacidil-sensitive component was significantly higher in female tissue than it was in male tissue, while no differences in single K(ATP) channel properties between genders were observed. Ischemia-reperfusion challenge induced significant intracellular Ca(2+) loading in male, but not female, cardiomyocytes. To test the hypothesis that SUR2A expression is the limiting factor in K(ATP) channel formation, we took different volumes of Kir6.2 and SUR2A complementary DNA (cDNA) from the same cDNA pool and subjected them to PCR. In order to obtain a band having 50% of the maximal intensity, a volume of SUR2a cDNA approximately 20 times the volume of Kir6.2 cDNA was required.
This study has demonstrated that female tissue expresses higher levels of functional cardiac K(ATP) channels than male tissue due to the higher expression of the SUR2A subunit, which has an impact on cardiac response to ischemia-reperfusion challenge.
本研究的主要目的是确定性别是否调节心脏ATP敏感性钾（K(ATP)）通道的表达和/或特性。
最近有证据表明，男性和女性对代谢应激的心脏反应不同，可能是由于内源性心脏保护机制（如K(ATP)通道）效率的性别特异性差异所致。
使用针对Kir6.2、Kir6.1和SUR2A亚基的特异性引物，对豚鼠心室组织的总RNA进行逆转录聚合酶链反应（RT-PCR）。使用抗Kir6.2和抗SUR2A抗体对心脏膜部分进行蛋白质免疫印迹分析。对分离的豚鼠心室肌细胞进行全细胞、单通道电生理学和数字落射荧光Ca(2+)成像。
RT-PCR显示，与雄性组织相比，雌性组织中SUR2A的信使核糖核酸水平较高，但Kir6.1和Kir6.2的水平不高，而与雄性组织相比，雌性组织心脏膜部分中Kir6.2和SUR2A蛋白的水平要高得多。在雄性和雌性组织中，K(ATP)通道开放剂匹那地尔（100微摩尔）均诱导外向全细胞电流。雌性组织中匹那地尔敏感成分的电流密度明显高于雄性组织，而两性之间单K(ATP)通道特性没有差异。缺血再灌注刺激在雄性心肌细胞中诱导显著的细胞内Ca(2+)负荷增加，而在雌性心肌细胞中未观察到。为了检验SUR2A表达是K(ATP)通道形成的限制因素这一假设，我们从同一cDNA文库中取不同体积的Kir6.2和SUR2A互补DNA（cDNA）进行PCR。为了获得强度为最大值50%的条带，所需的SUR2a cDNA体积约为Kir6.2 cDNA体积的20倍。
本研究表明，由于SUR2A亚基表达较高，雌性组织比雄性组织表达更高水平的功能性心脏K(ATP)通道，这对心脏对缺血再灌注刺激的反应有影响。
