目的：研究前胡丙素（ＰｒａＣ）的心脏负性肌力作用的机制．方法：使用Ｃａ２＋敏感的荧光指示剂Ｆｕｒａ２ＡＭ，在培养的新生鼠心肌细胞测定细胞内Ｃａ２＋的瞬间变化．结果：ＰｒａＣ１０、３０μｍｏｌ·Ｌ－１引起［Ｃａ２＋］ｉ瞬间变化最大值明显减少．ＰｒａＣ１０，３０μｍｏｌ·Ｌ－１能部分抑制ＣａＣｌ２４８ｍｍｏｌ·Ｌ－１及Ｂａｙｋ８６４４１００ｎｍｏｌ·Ｌ－１增加的［Ｃａ２＋］ｉ瞬间变化的峰值，但对［Ｃａ２＋］ｉ瞬间变化的基线水平没有明显的影响．Ｒｙａｎｏｄｉｎｅ３μｍｏｌ·Ｌ－１使［Ｃａ２＋］ｉ瞬间变化的幅度明显降低，在此基础上，ＰｒａＣ３０μｍｏｌ·Ｌ－１继续抑制［Ｃａ２＋］ｉ的瞬间变化．结论：ＰｒａＣ在完整心肌的负性肌力作用可能与其部分抑制兴奋收缩偶联过程中的Ｃａ２＋内流有关． Objective: To study the mechanism of the negative inotropic effect of PraC (PraC). Methods: Ca2 + sensitive fluorescent indicator Fura2  AM, in cultured neonatal rat cardiomyocytes measured intracellular Ca2 + transient changes. Results: The maximum instantaneous change of [Ca2 +] i induced by PraC10, 30μmol·L1 was significantly decreased. PraC10, 30μmol·L-1 could partially inhibit the peak of [Ca2 +] i transiently increased in CaCl24.8mmol·L-1 and Bayk8644100nmol·L-1, but there was no obvious change in the baseline level of [Ca2 +] i influences. Ryanodine 3μmol·L-1 [Ca2 +] i instantaneous changes in the magnitude of significantly reduced, on this basis, Pra  30μmol · L-1 continue to inhibit [Ca2] i transient changes. Conclusion: The negative inotropic effect of PraC in intact myocardium may be related to its partial inhibition of Ca2 + influx during excitatory-contractile coupling.