Objectives Exercise is a special kind of stressor. Moderate exercise will be helpful to improve cardiovascular function and enhance cardiac contractility. In contrast, exhaustive exercise (the intensity or duration of the exercise is beyond the physical endurance of human-beings) will lead to the exercise-induced myocardial. In the course of exhaustive exercise, there will be a general acceleration of the body metabolism and dramatic increase of blood and oxygen requirements. Consequently, the heart rate and blood output per pulse become higher and higher. Finally, this would have overshoot the endurance and the buffering mechanism of the myocardial, and then resulted in myocardial injury. Therefore, to explore the effective medicine that can protect the cardiac function or reduce the damage of myocardium is a essential topic in the field of the Sports Medicine.
In the present study, the protective effect of Sal. against ischaemia/reperfusion of repeated exhaustive swimming injury in the rats and the underlying mechanism was investigated by using the Langendorff isolated heart perfusion technique.
Methods Male Sprague-Dawley rats were randomly divided into four groups: control group, salidroside group (Sal), salidroside-repeated exhaustive swimming group (Sal-RES), repeated exhaustive swimming group (RES). The rats in control group and RES group were given 0.9%NaCl (3ml·kg-1·d) by lumbar injection two weeks. The rats in Sal- RES group and Sal group were given salidroside (30mg·kg-1·d) by lumbar injection two weeks. After two weeks, the rats in control group and Sal group were not to do any exercise. And the rats in Sal- RES group and RES group done repeated exhaustive exercise by swimming one week. The rats hearts of each group were taken after the last swimming day. In isolated rat heart, Langendorff technique was used to observe the effect of salidroside on left ventricular function before and after 30min ischaemia/60min reperfusion, respectively.
Results 1. In basic state, LVDP, + LVdp/dtmax,- LVdp/dtmax of the control group and Sal group have no significant difference among each other (P>0.05); compared with the Control group, LVDP, +LVdp / dtmax,- LVdp / dtmax of the Sal-RES group and the RES group decreased significantly (P < 0.05), and compared with Sal-RES, LVDP, +LVdp/dtmax,- LVdp/dtmax of the RES group are significantly lower (P <0.05). 2. After I/R, 60 minutes after reperfusion, recovery rate of LVDP, +LVdp/dtmax,-LVdp/dtmax of the Control group were 79.15%, 65.56%, 66.86%; Sal group were 78.97%, 65.61%, 71.84%; Sal-RES group were 76.52%, 44.35%, 47.33%; RES group were 53.22%, 42.01%, and 31.91%, respectively. Compare with the Sal. group, recovery rate ot the Control group has no significant difference (P> 0.05), compared to the Control group, Sal-RES group and the RES group decreased significantly (P <0.05), and the RES group, Sal-RES group decreased significantly (P <0.05 ).
Conclusions In this study, it is found that salidroside showed good benefits on the heart protection through suppressing the change of blood dynamics and the damage of cardiac caused by ischaemia/reperfusion. Such protection function of salidroside is probably related to its capability to enhance the cardiac anti-oxidant capacity.