Effects Of Parecoxib On Myocardial Function And Ventricular Remodeling In Short Or Long Term Treatment After Acute Myocardial Infarction In Rats

Objective: To investigate the effects of parecoxib on myocardial function in an experimental AMI model in the rat.Methods: Twenty-four adult male SD rats were randomly divided into 3 groups (n=8): sham operation group (group S), AMI group, parecoxib treatment group(group P). Group S was set as control in which the left anterior descending coronary (LAD) were exposed but not ligated. group AMI and group P underwent surgical LAD ligation.24 hours after operation. group P received parecoxib (8mg/kg intraperitoneal) daily for 3 days and group AMI received same volume of NaCl-0.9%.the forth day LVSP,LVEDP,±dp/dt_max was measured by the right common carotid artery catheterization; TXA₂ and PGI₂ were determined by RIA;infarct size was calculated by TTC staining.Results:1,Hemodynamic result: Compared with sham operation group, LVSP,±dp/dt_max were significantly lower but LVEDP was higher in AMI group and parecoxib treatment group. Compared with AMI group, LVSP,±dp/dt_max significantly increased but LVEDP decreased in parecoxib treatment group.2,Changes of PGI₂ and TXA₂ in plasma: Compared with sham operation group, PGI₂ and PGI₂/TXA₂ markly decreased but TXA₂ was elevated in AMI group and parecoxib treatment group. Compared with AMI group, PGI₂ and PGI₂/TXA₂ were notely higher but TXA₂ was lower in parecoxib treatment group.3,The myocardial infarct size was no significant difference (P>0.05) between AMI group and parecoxib treatment group.Conclusions:1,Parecoxib improved myocardial function of AMI rats by increasing the diastolic and contractile function, reducing the diastolic ventricular pressure.2,Parecoxib adjusted the ratio tends of PGI₂/TXA₂ in plasma toward the relative balance direction.3,There was no significantly effect of parecoxib on the myocardial infarct size in rats after acute myocardial infarction . Objective: To investigate the effects of a selective COX-2 inhibitor- parecoxib combined transection of the right cervical sympathetic trunk (TCST) on left ventricular remodeling (LVRM) after acute myocardial infarction in rats and the mechanism.Methods: Fourty adult male SD rats, 250-300g, underwent surgical left anterior descending branch (LAD) of coronary artery ligation and fed in cages for 4 weeks, were divided into 5 groups (n =8): sham operation (group S), LVRM control (group C), the right TCST(group T1), par treatment (group T2), TCST+Par (group T3). Four weeks after modeling disposal, hemodynamic measurement was maded by the right common carotid artery catheterization; TXA₂ and PGI₂ were determined by RIA;Left ventricular myocardial tissue volume (Vt),the volume density of myocardial cells (Vv),myocardial cell volume(Vc) were quantitatively analysed by stereological methods.Results:1,Hemodynamic result: Compared with group S, the cardiac functions significantly decreased in group C,groupT1,group T2 and group T3; Compared with group C, LVSP and±dp/dt _max significantly elevated , Meanwhile, LVEDP decreased in groupT1, group T2,and group T3.2,Changes of PGI₂ and TXA₂ in plasma: Compared with group S, PGI₂/TXA₂ ratio significantly decreased in other four groups, but TXA₂ levels significantly increased (P<0.05);Compared with group C, PGI₂,PGI₂/TXA₂ ratio increased, Meanwhile, TXA₂ reduced in groupT1, group T2,and group T3.3,Stereological results: Compared with group S, Vv,Vt and Vc significantly increased (P<0.05) in other four groups; Compared with group C ,Vv,Vt,Vc decreased in groupT1, group T2,and group T3; Compared with group T1 and T2, amelioration of myocardial function and decreasation of Vv,Vt,Vc more outstanding in group T3.Conclusions:1,Improving myocardial contractile function ,inhibiting cardiac cell hypertrophy compensatory and myocardial hypertrophy in some extent, the selective COX-2 inhibitor-parecoxib and transection of the right cervical sympathetic trunk (TCST) improved the myocardial function;ameliorated the process of ventricular remodeling after AMI. Parecoxib combined the right TCST had synergistic effect.2,Both parecoxib and the right TCST regulated PGI₂ levels up,TXA₂ levels down and the ratio of PGI₂/TXA₂ to relative balance .3,The mechanisms of parecoxib's inhibition of ventricular remodeling after MI were possibly due to parecoxib's strong analgesic effect to inhibit the sympathetic nerve excitability;reduce the tension of the sympathetic nervous system;adjust the relative balance of PGI₂/TXA₂.