Expression patterns of different isoforms of aquaporins in isoproterenolinduced myocardial infarction model in rat treated with Terminalia arjuna Bark extract

Aquaporins (AQPs) are found to express in myocardium and their involvement in myocardial water balance have been figured out quite well as they are primarily associated with the transportation of water and other solutes like glycerol and urea. In the present study, we investigated the levels of expression of AQP sub-types in normal myocardium and their changes in the process of edema formation and cardiac dysfunction following myocardial infarction by isoproterenol as well as after treatment with Terminalia arjuna methanolic extract. The qPCR analysis demonstrated an up-regulation of certain aquaporin genes like aqp1, aqp4, aqp5 and aqp7 in the myocardial infarcted group of rats induced by isoproterenol. Again, the treatment with methanolic extract of T. arjuna was found to down-regulate these aqp genes, thereby suggesting a possible co-relation between these two. In addition, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were found to increase in the infarcted group of rats, followed by lowering of these two enzyme levels in the treated group. Histopathological study quite clearly demonstrated that the myocardium from infarcted group displayed muscle separation and infiltration of lymphocytes, whereas treatment of myocardium from infarcted group with T. arjuna extract revealed a decrease in the degree of muscle separation and inflammatory response. Thus, our findings suggest the possible role of certain AQPs in isoproterenol induced myocardial infarction and also the remedial effects of T. arjuna in reverting the condition back to normal by lowering their expression levels. The enhanced expression levels of the aforementioned AQPs are quite indicative of the fact that these can serve as prognostic markers for myocardial infarction.