Title: 1038 GENE EXPRESSION OF CARDIAC ACE2/ACE AND MAS RECEPTOR IN EXPERIMENTAL HYPERTENSIVE RATS
Abstract: Objectives: Inter-regulation between components of the RAS is common, but little is known about the direct regulatory effects between cardiac ACE2/ACE and Mas receptor. This study was to examine if the expression of the cardiac ACE2/ACE and Mas receptor changes in hypertensive rats treated with enalapril and losartan. Methods: Forty rats were divided into 4 groups: sham operated (control, n = 10), rats with the aortic ligation (AL, n = 10), AL rats fed enalapril (20 mg kg−1 d−1, n = 10), and AL rats fed losartan (30 mg kg−1 d−1, n = 10). BP was recorded using a tail-cuff method. After 4 weeks of treatment, the levels of ACE2/ACE and Mas receptor in the heart were examined by RT-PCR and western blotting. Results: Cardiac ACE mRNA and ACE protein levels were greater in AL rats than in the control (P < 0.05). In AL rats with enalapril administration, cardiac ACE mRNA and its protein levels were decreased (P < 0.01), but losartan did not affect their levels. However, cardiac ACE2 mRNA and protein levels were lower in AL rats than in the control (P < 0.01). Both enalapril and losartan increased the levels of cardiac ACE2 expression, and BP was lower (P < 0.05). Cardiac Mas mRNA level rose in AL rats treated with losartan, but not enalapril. Conclusions: Our data demonstrated that administration of enalapril and losartan increased the ratio of cardiac ACE2/ACE mRNA levels. Losartan significantly elevated the cardiac Mas expression but not enalapril. These findings suggest that AT1 blockade might increase the activity of the cardiac ACE2-Ang (1-7)-Mas axis of the RAS.