The Effect of Losartan Versus Telmisartan on Renal Hemodynamics Responses to Angiotensin II administration in Male and Female Rats

Background. The renin–angiotensin system (RAS) is crucial in regulating blood pressure, fluid volume, and sodium balance in the body. Overactivation of this system can lead to the development of several medical conditions, such as kidney, and cardiovascular disorders. Losartan and telmisartan are two common angiotensin II (Ang II) receptor blockers (ARBs) which used for hypertension therapy. Both of these blockers affect renal blood flow (RBF), and this study aimed to compare the effects of losartan and telmisartan on the (RBF) and renal vascular resistance (RVR) responses to Ang II infusion in male and female rats. Methods. Three groups of males and three groups of females Wistar rats were assigned, and they randomized in vehicle, losartan (10 mg/kg), and telmisartan (10 mg/kg) treated groups. Subsequently, under anesthesia, mean arterial pressure (MAP), RBF and RVR responses to graded doses of Ang II administration under controlled renal perfusion pressure (RPP) were determined. Results. Infusion of Ang II resulted in dose-dependent increases in MAP that were similar in both male (P _treat < 0.0001) and female (P _treat < 0.002) rats. However, in females, the losartan group showed significantly lower MAP (P _group = 0.018) and RPP (P _group = 0.019) compared to the other groups. Ang II infusion led to a dose-dependent percentage change of RBF decreasing and RVR increasing in the vehicle group for both genders, and these changes were significantly different from others group ((P < 0.05). Additionally, urine flow was increased significantly in telmisartan group when compared with others groups (P < 0.05). Conclusion. Losartan in female rats is more effective in reducing MAP than telmisartan, while similar RBF and RVR responses to Ang II infusion were conducted in losartan and telmisartan groups.