Effects Of The Transection Of Cervial Sympathetic Trunk On Left Venrticular Remodeling After Acute Mycardial Infarction In Rats

Objective: To investigate the effects and mechanisms of transection of cervical sympathetic trunk (TCST) on left ventricular remodeling (LVRM) after acute myocardial infarction in rats , and supply the experimental information for scholars to treat LVRM with stellate ganglion block at clinic.Methods: Sixty-four adult male SD rats were randomly divided into four groups(n=16): sham operation group, LVRM control group, left TCST group and right TCST group. Sham operation group was set as control in which both the left anterior descending coronary (LAD) and cervical sympathetic trunk were exposed . As soon as the LAD was ligated, left or right cervical sympathetic trunk was transected in the left and right TCST groups , otherwise it was exposed but not transected in LVRM control group. Then the LVRM model was established by feeding the survivals of ligating LAD four weeks . Four weeks later, hemodynamic measurement was made . Plasma IL-10 and TNF-αlevels were analysed by ELISA. Subsequently the ratio of IL-10/ TNF-αwas calculated . The hearts were harvested and the weights of left ventricle and left ventricle weight indexes were measured and calculated respectively. Then the hearts were sliced transversely preparing for stereological analysis and wall thickness detection . Finally, The c-fosmRNA expression in myocardium was determined by RT-PCR.Results:1. MI reduced cardiac function as indicated by decreases in LVSP and±dp/dt max and increases in LVEDP. All of the functional parameters were unexpectedly worsend in the left TCST group. But in contrast, right TCST treatment increased +dp/dt max and reduced LVEDP.2. We observed a significantly increased left ventricle weight indexes , V(mt) and V(mc) and a decreased TR in all the infarcted rats, which suggested LVRM. Moreover, a significantly decreased left ventricle weight indexes , V(mt) and V(mc), and an increased TR in the Right TCST treatment rats were also observed, which suggested right TCST might reduce the hypertrophy of the myocytes and myocardium, and inhibit LVRM. But left TCST was just on the contrary.3. The expressing of c-fosmRNA in myocardium was increased in the process of LVRM post-MI. But right TCST down-regulated the increased c-fos mRNA expression, and unfortunately left TCST up-regulated it.4. Right TCST treatment led to decrease the level of TNF-α, and increase the IL-10 and the ratio of IL-10/ TNF-αas compared with LVRM controls. However , left TCST treatment led to furtherly increase the level of TNF-αand IL-10, and decrease the IL-10/ TNF-αratio.Conclusion:1. Right TCST might reduce the hypertrophy of the myocytes and myocardium, inhibit LVRM, and improve the cardiac function. But oppositely, left TCST had no effects of inhibiting LVRM, and in these rats cardiac function was unexpectedly worsened.2. The mechanism right TCST inhibits LVRM was not only the decrease in TNF-αand c-fosmRNA expressions, but also an increase in IL-10/ TNF-αratio. Similarly, left TCST treatment did not only led to an increase in TNF-αand c-fosmRNA expressions, but also a decrease in IL-10/ TNF-αratio, therefore LVRM developed.3. Related to the laterality which is known to exist in the sympathetic nervous system regulating the heart, the effects of left and right TCST on LVRM were different.