Effect of aliskiren, telmisartan and torsemide on cardiac dysfunction in l-nitro arginine methyl ester (l-NAME) induced hypertension in rats

Comparative study of cardio protective effect of aliskiren, telmisartan, and torsemide was carried out on l-nitro arginine methyl ester (l-NAME) induced hypertension in rats. The three drugs were given daily for 8 weeks simultaneously with l-NAME, with a control group for each drug and l-NAME. The degree of protection was assessed by measurement of systolic blood pressure and heart rate of animals every two weeks. At the end of the experimental period blood sampling was carried out for estimation of the level of NO2 (-)/NO3 (-). After which animals were sacrificed for heart dissection to detect collagen types I and III gene expression. Histopathological study was done to evaluate the extension of collagen deposits. The study revealed that the three drugs decreased blood pressure significantly compared to l-NAME. There was no significant difference between aliskiren and telmisartan in all measurements, but there was significant decrease in measurements of both aliskiren and telmisartan treated groups compared to torsemide starting from 4th week. There were insignificant changes in pulse rate values between the three l-NAME treated groups through the experiment. The three drugs significantly increased NO compared to l-NAME. Collagen I and III gene expression was significantly decreased by the three drugs but the highest percentage of inhibition was with telmisartan compared to l-NAME. Comparing the percentage inhibition of cardiac fibrosis, there was insignificant difference between telmisartan and torsemide treated groups while both were superior to aliskiren. In conclusion, further experimental studies are required to elucidate the potential cardioprotective mechanisms of aliskiren, telmisartan and torsemide, and assess their efficacy in treatment of heart failure.