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目的我们前期的研究发现LPA受体在幼年大鼠心脏的表达显著高于成年的表达,提示LPA信号在心脏收缩功能尚未成熟时可能具有更为重要的调节作用。本研究通过观察LPA对此未成熟阶段心肌细胞钙瞬变和收缩力的作用,探讨LPA信号对幼年心肌兴奋-收缩耦联的影响。方法 Langendorff装置逆向灌流胶原酶分离获得不同发育阶段大鼠心肌细胞;采用IonOptix细胞收缩和钙离子浓度同步测定系统进行心肌细胞收缩力和钙瞬变的测定;Western blot检测不同发育阶段心肌细胞LPA受体的表达。结果 LPA对出生后14天和21天大鼠心肌细胞的收缩和钙瞬变均没有显著影响,表明LPA信号并不参与出生后14-21天大鼠心肌细胞的兴奋-收缩耦联过程和心肌细胞收缩。在大鼠出生后发育过程中,LPA受体在心肌细胞的表达在出生后14天已显著下调,不同于在整体心脏表达下调的时间点(P21d),这可能是LPA对此发育阶段心肌细胞的收缩和钙瞬变均不产生影响的原因,提示在出生后14天LPA信号对心肌细胞的发育调节功能可能即已减弱或消失。结论 LPA信号对出生后14天及之后心肌收缩和钙瞬变无显著影响,但尚不能排除LPA对出生后更早期的未成熟心肌细胞收缩和兴奋-收缩耦联的作用。
PURPOSE Our previous study found that expression of LPA receptor was significantly higher in adult rat hearts than in adult rats, suggesting that LPA signaling may play a more important regulatory role when cardiac contractility is immature. In this study, we observed the effect of LPA on calcium transients and contractility of cardiomyocytes in this immature stage and explored the effect of LPA signaling on the excitatory-contractile coupling of young myocardial cells. Methods Langendorff apparatus was used to separate rat cardiomyocytes isolated from collagenase at different developmental stages. The contractile force and calcium transient of cardiomyocytes were measured by IonOptix cell contraction and calcium concentration simultaneously. Western blot was used to detect the LPA of cardiomyocytes in different developmental stages Body expression. Results LPA had no significant effect on contraction and calcium transient of rat cardiomyocytes at 14 days and 21 days after birth, indicating that LPA signal did not participate in the excitation-contraction coupling process and cardiac muscle of rat cardiomyocytes during 14-21 days after birth Cells contract. During postnatal development in rats, the expression of LPA receptors in cardiomyocytes was significantly down-regulated at day 14 postnatal, unlike at the point of total heart expression down-regulation (P21d), which may be the reason that LPA affects cardiomyocytes in this developmental stage Contraction and calcium transients, suggesting that the regulatory function of LPA signaling on cardiomyocytes may have diminished or disappeared 14 days after birth. Conclusions LPA signaling has no significant effect on myocardial contractility and calcium transients on day 14 and after birth, but it is not yet possible to rule out the effect of LPA on contractile and excitatory-contractile coupling of immature cardiomyocytes after birth.