Gambassi G, Carbonin P, Capogrossi M C
Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD.
Cardiologia. 1992 Aug;37(8):569-71.
Ischemia is associated with myocardial acidosis which recovers upon reperfusion. In such conditions, alpha 1-adrenergic stimulation is arrhythmogenic. We used single cardiac myocytes loaded with the pH fluorescent dye, SNARF-1, to determine if a modulation of pH could explain the effect of alpha 1-adrenergic stimulation. Cells were exposed to acidosis (CO2 15%) for 15 min and then normocapnia restored. During acidosis, alpha 1-adrenergic stimulation caused an increase in pH which was abolished by blocking Na+/H+ exchange with ethylisopropylamiloride (EIPA). After removal of acidosis aftercontractions were manifest in 8 out of 10 and 1 out of 5 cells in the presence of an alpha 1-adrenergic agonist and in control, respectively (p < 0.001). EIPA abolished the occurrence of after contractions. Thus, the arrhythmogenicity of alpha 1-adrenergic stimulation depends on activation of Na+/H+ exchanger.
缺血与心肌酸中毒相关，再灌注时酸中毒会恢复。在这种情况下，α1 - 肾上腺素能刺激会引发心律失常。我们使用加载了pH荧光染料SNARF - 1的单个心肌细胞来确定pH的调节是否可以解释α1 - 肾上腺素能刺激的作用。细胞暴露于酸中毒（二氧化碳浓度15%）15分钟，然后恢复正常二氧化碳浓度。在酸中毒期间，α1 - 肾上腺素能刺激导致pH升高，而用乙基异丙基氨氯吡咪（EIPA）阻断钠/氢交换可消除这种升高。去除酸中毒后，在存在α1 - 肾上腺素能激动剂的情况下，10个细胞中有8个出现后收缩，而在对照中5个细胞中有1个出现后收缩（p < 0.001）。EIPA消除了后收缩的发生。因此，α1 - 肾上腺素能刺激的致心律失常性取决于钠/氢交换体的激活。
