Cardiomyocytes from postinfarction failing rat hearts have improved ischemia tolerance
Cardiomyocytes from postinfarction failing rat hearts have improved ischemia tolerance
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DOI：
10.1152/ajpheart.00796.2008
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发表时间：
2009-03-01
影响因子：
4.8
通讯作者：
Brors, Odd
中科院分区：
文献类型：
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作者：
Sharikabad, Mohammad Nouri;Aronsen, Jan Magnus;Brors, Odd
Sharikabad MN，Aronsen JM，Haugen E，Pedersen J，Moller AS，Mork HK，Aass HC，Sejersted OM，Sjaastad I，Brors O.梗死后衰竭大鼠心脏的心肌细胞改善了缺血耐受性。Am J Physiol Heart Circ Physiol 296：H787-H795，2009.首次发表于2009年1月9日; doi：10.1152/ajpheart.00796.2008。充血性心力衰竭（CHF）时心肌Ca ~（2+）和Na ~+处理的改变可能通过增加再灌注Ca ~（2+）超负荷而降低对缺血的耐受性。本研究的目的是通过测定衰竭大鼠心肌细胞的酶释放、细胞死亡、ATP水平和细胞内Ca ~（2+）和Na ~+来研究缺氧-复氧的耐受性。在异氟醚麻醉期间通过结扎左冠状动脉在Wistar大鼠中诱导CHF，之后在6周内发生心力衰竭。分离的心肌细胞培养24小时，随后暴露于4小时的缺氧和2小时的复氧。细胞损伤以乳酸脱氢酶（LD）释放测定，细胞死亡以碘化丙啶摄取测定，ATP通过萤火虫荧光素酶测定。用放射性同位素测定细胞内Ca ~（2+）和Na ~+，用Fluo-3 AM测定细胞内游离Ca ~（2+）浓度（[Ca ~（2+）]（i））。CHF细胞在缺氧-复氧后LD释放和细胞死亡的增加较少，缺氧后ATP水平的相对降低较少。在缺氧期间，CHF细胞积累的Na+比假手术细胞少（117与267 nmol/mg蛋白质）。在缺氧过程中，CHF细胞的[Ca 2 +]（i）比假手术细胞低得多（缺氧4小时时为423 vs. 1，766任意单位），在再氧合120分钟后，CHF细胞的交换性Ca 2+增加比假手术细胞少得多（1.4 vs. 6.7 nmol/mg蛋白）。雷诺嗪，晚Na+电流的抑制剂，显着衰减的增加交换性Ca 2+和LD释放假细胞复氧后的增加。这支持了缺氧过程中Na+积累的差异导致复氧过程中Ca 2+积累的差异的建议。缺氧和复氧的耐受性是令人惊讶的高，在CHF比假心肌细胞，可能解释较低的缺氧介导的Na+的积累和随后较低的Ca 2+的积累在CHF复氧后。
Sharikabad MN, Aronsen JM, Haugen E, Pedersen J, Moller AS, Mork HK, Aass HC, Sejersted OM, Sjaastad I, Brors O. Cardiomyocytes from postinfarction failing rat hearts have improved ischemia tolerance. Am J Physiol Heart Circ Physiol 296: H787-H795, 2009. First published January 9, 2009; doi:10.1152/ajpheart.00796.2008.-Altered myocardial Ca2+ and Na+ handling in congestive heart failure (CHF) may be expected to decrease the tolerance to ischemia by augmenting reperfusion Ca2+ overload. The aim of the present study was to investigate tolerance to hypoxia-reoxygenation by measuring enzyme release, cell death, ATP level, and cell Ca2+ and Na+ in cardiomyocytes from failing rat hearts. CHF was induced in Wistar rats by ligation of the left coronary artery during isoflurane anesthesia, after which cardiac failure developed within 6 wk. Isolated cardiomyocytes were cultured for 24 h and subsequently exposed to 4 h of hypoxia and 2 h of reoxygenation. Cell damage was measured as lactate dehydrogenase (LD) release, cell death as propidium iodide uptake, and ATP by firefly luciferase assay. Cell Ca2+ and Na+ were determined with radioactive isotopes, and free intracellular Ca2+ concentration ([Ca2+](i)) with fluo-3 AM. CHF cells showed less increase in LD release and cell death after hypoxia-reoxygenation and had less relative reduction in ATP level after hypoxia than sham cells. CHF cells accumulated less Na+ than sham cells during hypoxia (117 vs. 267 nmol/mg protein). CHF cells maintained much lower [Ca2+](i) than sham cells during hypoxia (423 vs. 1,766 arbitrary units at 4 h of hypoxia), and exchangeable Ca2+ increased much less in CHF than in sham cells (1.4 vs. 6.7 nmol/mg protein) after 120 min of reoxygenation. Ranolazine, an inhibitor of late Na+ current, significantly attenuated both the increase in exchangeable Ca2+ and the increase in LD release in sham cells after reoxygenation. This supports the suggestion that differences in Na+ accumulation during hypoxia cause the observed differences in Ca2+ accumulation during reoxygenation. Tolerance to hypoxia and reoxygenation was surprisingly higher in CHF than in sham cardiomyocytes, probably explained by lower hypoxia-mediated Na+ accumulation and subsequent lower Ca2+ accumulation in CHF after reoxygenation.