Effect of parecoxib on cardiac function after acute myocardial infarction in rats

Objective To investigate the effect of parecoxib on cardiac function after acute myocardial infarction (AMI) in rats. Methods Twenty-four adult male SD rats, weighing 230-250 g, were randomly divided into 3 groups ( n = 8 each): group Ⅰ sham operation (group S), group Ⅱ AMI and group Ⅲ parecoxib (group P). Myocardial infarction was induced by ligation of left anterior descending branch (LAD) of coronary artery in group Ⅱ and Ⅲ . In group S, LAD and cervical sympathetic trunk were exposed but not ligated and transected.Group P received intrperitoneal parecoxib 8 mg/kg once a day for 3 days 24 h after ligation of LAD, while group AMI received normal saline instead. At 4th day after ligation LAD, the left ventricular systolic pressure ( LVSP),left ventricular end-diastolic pressure (LVEDP) and ± dp/dtmax were measured and recorded. Blood samples were taken from common carotid artery to determine the plasma concentrations of TXA2 and PGI2 and PGI2/TXA2 was calculated. Then the animals were sacrificed and hearts removed. Myocardial infarct size of left venicle was calculated. Results Compared with group S, LVSP, ± dp/dtmax, plasma concentrations of PGI2 and PGI2/TXA2 were significantly decreased, while LVEDP and plasma concentrations of TXA2 increased in group AMI and P( P ＜0.05). Compared with group AMI, LVSP, ± dp/dtmax, plasma concentrations of PGI2 and PGI2/TXA2 were significantly decreased, while LVEDP and plasma concentrations of TXA2 increased in group P ( P ＜ 0.05). There was no significant difference in myocardial infarct size between group AMI and P (P ＞ 0.05). Conclusion Parecoxib can improve cardiac function after AMI in rats and the mechanism is related to regulation of the balance of PGI2/TXA2. Key words: Cyclooxygenase 2 inhibitors; Myocardial infarction; Heart function tests