Hyponatraemia is defined as a serum sodium concentration of <135 mEql/L and is the most common electrolyte disturbance in patients with chronic heart failure. We hypothesize that hyponatraemia may induce Ca²⁺ overload and enhance reactive oxygen species (ROS) production, which will exacerbate myocardial injury more than normonatraemia. We investigated the effect of hyponatraemia on the ability of the heart to recover from ischaemia/reperfusion episodes. Cardiomyocytes were obtained from 1‐ to 3‐day‐old Sprague Dawley rats. After isolation, cardiomyocytes were placed in Dulbecco's modified Eagle's medium (DMEM) containing low sodium concentration (110, 120, or 130 mEq/L) or normal sodium concentration (140 mEq/L) for 72 hours. Exposure of cardiomyocytes to each of the low‐sodium medium significantly increased both ROS and intracellular Ca²⁺ levels compared with the exposure to the normal‐sodium medium. In vivo, 8‐week‐old male Sprague Dawley rats were divided into four groups: control group (Con), furosemide group (Fur), low‐sodium diet group (Lsd) and both furosemide and low‐sodium diet group (Fur + Lsd). The hearts subjected to global ischaemia exhibited considerable decrease in left ventricular developed pressure during reperfusion, and the size of infarcts induced by ischaemia/reperfusion significantly increased in the Fur, Lsd and Fur + Lsd compared with that in the Con. Hyponatraemia aggravates cardiac susceptibility to ischaemia/reperfusion injury by Ca²⁺ overload and increasing in ROS levels.

中文翻译：

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低钠血症加重了心脏对缺血/再灌注损伤的敏感性。

低钠血症的定义为血清钠浓度<135 mEql / L，是慢性心力衰竭患者最常见的电解质紊乱。我们假设低钠血症可能诱导Ca ²⁺超负荷并增强活性氧（ROS）的产生，与正常人相比，这会加剧心肌损伤。我们调查了低钠血症对心脏从缺血/再灌注发作中恢复的能力的影响。从1到3天大的Sprague Dawley大鼠获得心肌细胞。分离后，将心肌细胞置于含有低钠浓度（110、120或130 mEq / L）或正常钠浓度（140 mEq / L）的Dulbecco改良的Eagle培养基（DMEM）中放置72小时。将心肌细胞暴露于每种低钠培养基中都会显着增加ROS和细胞内Ca ²⁺与暴露于普通钠介质中的水平相比。在体内，将8周大的雄性Sprague Dawley大鼠分为四组：对照组（Con），速尿组（Fur），低钠饮食组（Lsd）以及速尿和低钠饮食组（Fur + Lsd）。与Con相比，在全血缺血期间，心脏在再灌注过程中左心室形成的压力显着降低，并且在Fur，Lsd和Fur + Lsd中，由缺血/再灌注引起的梗死面积明显增加。低钠血症加重Ca ²⁺超负荷并增加ROS水平，加剧心脏对缺血/再灌注损伤的敏感性。