Effects of Losartan and Amlodipine on Left Ventricular Remodeling and Function in Young Stroke-Prone Spontaneously Hypertensive Rats.

BACKGROUND The purpose of this study was to evaluate the effects of prehypertensive losartan and amlodipine administration on left ventricular (LV) remodeling and function in spontaneously hypertensive rats-stroke prone (SHRSP). METHODS Spontaneously hypertensive rats-stroke prone were prehypertensively administered losartan, amlodipine, or vehicle. Wistar-Kyoto rats were used as a control. Blood pressure of the rats was determined by tail-cuff method, and LV structure and function were measured by echocardiography and LV cannulation. Collagen volume fraction was analyzed by picrosirius red staining. Protein expressions of brain natriuretic peptide (BNP) and angiotensin II type 1 (AT1R) and type 2 (AT2R) receptors were determined by use of the Western blotting method. RESULTS Although both drugs downregulated BNP protein expression, the LV remodeling and function were more improved with losartan than with amlodipine treatment. Losartan upregulated AT1R and downregulated AT2R protein expression. CONCLUSIONS Both drugs inhibited LV remodeling and improved LV function in prehypertensively treated SHRSP. Losartan provided better continued heart protection, potentially due to its persistent inhibition of AT1R and activation of AT2R in the myocardium. KEY WORDS Amlodipine; Blood pressure; Heart; Losartan; Prehypertension.