低剂量双酚A对雌性大鼠心室肌细胞钙火花的影响及其机制

Effects of low concentration bisphenol A on calcium spark of female adult rat cardiac myocytes and its mechanism

目的探讨低剂量双酚A(BPA)对雌性大鼠心室肌细胞钙火花的影响及其机制。方法选用20只10~16周,体重200~250 g的二级清洁健康雌性SD大鼠,处死后对其心室肌细胞进行体外分离,并按实验要求将细胞分成对照组和BPA组(添加浓度为10^(-9)mmol/L的BPA),每组细胞至少来源于3只大鼠,每只大鼠取8~10个细胞。采用共聚焦显微镜检测两组钙火花,钙离子成像系统检测两组钙瞬变及肌浆网内钙负荷。结果共聚焦显微镜下可见两组均有明亮钙火花出现。BPA组钙火花频率、钙瞬变峰值高于对照组,钙瞬变tau值短于对照组,差异有高度统计学意义(P<0.01)。两组钙火花峰值比较,差异无统计学意义(P>0.05)。稳态下,BPA组肌浆网钙负荷高于对照组,差异有统计学意义(P<0.05);两组的肌浆网钙负荷tau值比较,差异无统计学意义(P>0.05)。静态下,两组肌浆网钙负荷比较,差异无统计学意义(P>0.05)。结论在BPA的作用下,雌性成年大鼠心肌细胞肌浆网内的钙负荷随着心肌细胞的收缩逐步增加,雷诺丁受体的开放率也逐步增加,促进心肌细胞舒张期肌浆网的Ca^(2+)漏出,增加钙火花的频率。

Objective To investigate the effects and the mechanisms of bisphenol A(BPA)on calcium spark of the female adult rat cardiac myocytes.Methods Twenty healthy female SD rats weighing 200-250 g at 10-16 weeks old were selected and their cardiac myocytes were isolated in vitro after death.According to the experimental requirements,the cells were divided into control group and BPA group(10^(-9)mmol/L BPA was added).Cells in each group were obtained from at least three rats,and eight to ten cells were taken from each rat.Confocal microscope was used to detect calcium sparks in both groups,and calcium ion imaging system was used to detect calcium transients and calcium load of sarcoplasmic reticulum in two groups.Results Under confocal microscope,bright calcium sparks appeared in both groups.Calcium spark frequency and calcium transient peak value in BPA group were higher than those in control group,while calcium transient tau value was shorter than that in control group,the differences were highly statistically significant(P<0.01).There was no significant difference between the two groups in calcium spark peak value(P>0.05).In steady state,the calcium load of sarcoplasmic reticulum in BPA group was higher than that in control group,and the difference was statistically significant(P<0.05).There was no significant difference in tau value of sarcoplasmic reticulum calcium load between the two groups(P>0.05).At static state,there was no significant difference in the calcium load of sarcoplasmic reticulum between the two groups(P>0.05).Conclusion Under the action of BPA,the calcium load in the sarcoplasmic reticulum of female adult rat cardiomyocytes gradually increased with the contraction of cardiomyocytes,and the opening rate of renotin receptor also gradually increased,promoting Ca^(2+) leakage from the sarcoplasmic reticulum of cardiomyocytes during diastolic period,and increasing the frequency of calcium spark.