目的 :对不同剂量的左旋精氨酸 (L - Arg)对心脏的作用进行初步探讨。　　方法 :将 40只大鼠分成 5组 ,每组 8只 ,分别为 L - Arg 0 .1、1、10、2 0及 40 mmol/ L组。用 L angendorff离体大鼠心脏逆行灌流法 ,记录用药前后左心室收缩压、左心室内压正负相最大变化速率以及心率的变化。　　结果 :与自身对照 (用药前 )比较 ,L - Arg 0 .1mmol/ L组所有观察指标无统计学差异 ;L - Arg 1mmol/ L组所有观察指标显著升高 (P<0 .0 1) ;L - Arg 10 mmol/ L组仅左心室内压正负相最大变化速率值降低 (P<0 .0 1) ;L - Arg 2 0 mmol/ L组及 40 mmol/ L组所有观察指标显著降低 (P<0 .0 1)。　　结论 :1生理浓度 L - Arg 0 .1mmol/ L对大鼠离体心脏功能无明显影响。2 L - Arg 1mmol/ L对大鼠离体心脏功能有正性变时 ,变力作用。3 L - Arg 2 0 mmol/ L及 40 mmol/ L时对大鼠离体心脏左心室压力指标及心率产生明显抑制作用。 Objective: To investigate the effects of different doses of L - arginine on heart. Methods: Forty rats were divided into 5 groups with 8 mice in each group: L - Arg 0 .1, 1, 10, 20 and 40 mmol / L groups. The left ventricular systolic pressure, the maximum rate of positive and negative changes of left ventricular pressure, and heart rate were recorded before and after treatment with Langendorff rat heart retrograde perfusion method. Results: Compared with self - control group (before treatment), all the indexes of L - Arg 0 .1 mmol / L group had no statistical difference; all the indexes of L - Arg 1 mmol / L group were significantly increased (P <0.01); L - Arg 10 mmol / L group, only the maximum changes of positive and negative rates of left ventricular pressure decreased (P <0.01); all the indexes of L - Arg 20 mmol / L and 40 mmol / L groups were significantly lower (P <0. 01). Conclusion: 1 The physiological concentration of L - Arg 0 .1mmol / L had no significant effect on isolated rat heart function. 2 L - Arg 1 mmol / L had a positive effect on isolated rat heart function, and had variable force. 3 L - Arg 2 0 mmol / L and 40 mmol / L significantly inhibited left ventricular pressure and heart rate in isolated rat hearts.