Influence of age and run training on cardiac Na+/Ca2+ exchange.
Influence of age and run training on cardiac Na+/Ca2+ exchange.
复制标题
年龄和跑步训练对心脏 Na /Ca2 交换的影响。
DOI：
10.1152/japplphysiol.00551.2003
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Moore,RussellL
中科院分区：
文献类型：
--
作者：
Mace,LisaC;Palmer,BradleyM;Brown,DavidA;Jew,KorinneN;Lynch,JoshuaM;Glunt,JasonM;Parsons,ToddA;Cheung,JosephY;Moore,RussellL
Effects of age and training on myocardial Na+/Ca2+exchange were examined in young sedentary (YS; 14-15 mo), aged sedentary (AS; 27-31 mo), and aged trained (AT; 8- to 11-wk treadmill run training) male Fischer Brown Norway rats. Whole heart performance and isolated cardiocyte Na+/Ca2+exchange characteristics were measured. At the whole heart level, a small but significant slowing of late isovolumic left ventricular (LV) relaxation, which may be indicative of altered Na+/Ca2+exchange activity, was seen in hearts from AS rats. This subtle impairment in relaxation was not observed in hearts from AT rats. At the single-cardiocyte level, late action potential duration was prolonged, resting membrane potential was more positive, and overshoot potential was greater in cardiocytes from AS rats than from YS rats (P< 0.05). Training did not influence any of these age-related action potential characteristics. In electrically paced cardiocytes, neither shortening nor intracellular Ca2+concentration ([Ca2+]i) dynamics was influenced by age or training. Similarly, neither age nor training influenced the rate of [Ca2+]iclearance via forward (Nain+/Caout2+) Na+/Ca2+exchange after caffeine-induced Ca2+release from the sarcoplasmic reticulum or cardiac Na+/Ca2+exchanger protein (NCX1) expression. However, when whole cell patch-clamp techniques combined with fluorescence microscopy were used to evaluate the ability of Na+/Ca2+exchange to alter cytosolic [Ca2+] ([Ca2+]c) under conditions where membrane potential (Vm) and internal and external [Na+] and [Ca2+] could be controlled, we observed age-associated increases in forward Na+/Ca2+exchange-mediated [Ca2+]cclearance (P< 0.05) that were not influenced by training. The age-related increase in forward Na+/Ca2+exchange activity provides a hypothetical explanation for the late action potential prolongation observed in this study.
