Increased intracellular [dATP] enhances cardiac contraction in embryonic chick cardiomyocytes.
Increased intracellular [dATP] enhances cardiac contraction in embryonic chick cardiomyocytes.
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DOI：
10.1002/jcb.21780
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发表时间：
2008-08-15
影响因子：
4
通讯作者：
Chase PB
中科院分区：
文献类型：
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作者：
Schoffstall B;Chase PB
虽然ATP是心脏收缩的生理底物，但在体外，当仅10%的ATP底物被2 '-脱氧-ATP（dATP）取代时，心脏收缩力显著增强。为了确定活心肌细胞内细胞内[dATP]（[dATP]i）增加的功能效应，我们使用不同外源性dATP/ATP比率的高渗负荷，但总核苷酸浓度恒定，以提高鸡胚心肌细胞收缩单层的[dATP]i。通过稀释与dATP平行加入的染料估计[dATP]i的增加。检查细胞活力、平均收缩幅度、收缩/舒张率、自发搏动频率和Ca 2+瞬时幅度和动力学。当总[dATP]i高于~70 μM时，自发收缩停止，当[dATP]i高于~100 μM时，还观察到膜起泡，与细胞凋亡一致。有趣的是，约60 μM的[dATP]i（比基础[dATP]i水平增加约40%）增强了收缩幅度以及收缩和舒张速率，而不影响搏动频率。当总[dATP]i为~60 μM或更低时，我们发现Ca 2+瞬变无显著变化。这些数据表明，有一个“最佳”浓度的外源性负载的[dATP]i，在受控条件下，可以提高活心肌细胞的收缩性，而不影响搏动频率或Ca 2+瞬变。
Although ATP is the physiological substrate for cardiac contraction, cardiac contractility is significantly enhanced in vitro when only 10% of ATP substrate is replaced with 2’-deoxy-ATP (dATP). To determine the functional effects of increased intracellular [dATP] ([dATP]i) within living cardiac cells, we used hypertonic loading with varying exogenous dATP/ATP ratios, but constant total nucleotide concentration, to elevate [dATP]i in contractile monolayers of embryonic chick cardiomyocytes. The increase in [dATP]i was estimated from dilution of dye added in parallel with dATP. Cell viability, average contractile amplitude, rates of contraction/relaxation, spontaneous beat frequency, and Ca2+ transient amplitude and kinetics were examined. At total [dATP]i above ~70 μM, spontaneous contractions ceased, and above ~100 μM [dATP]i, membrane blebbing was also observed, consistent with apoptosis. Interestingly, [dATP]i of ~60 μM (~40% increase over basal [dATP]i levels) enhanced both amplitude of contraction and the rates of contraction and relaxation without affecting beat frequency. With total [dATP]i of ~60 μM or less, we found no significant change in Ca2+ transients. These data indicate that there is an “optimal” concentration of exogenously loaded [dATP]i that under controlled conditions can enhance contractility in living cardiomyocytes without affecting beat frequency or Ca2+ transients.