Myocardial renin is neither necessary nor sufficient to initiate or maintain ventricular hypertrophy

We tested the hypothesis that the myocardial renin-angiotensin system (RAS) is both necessary and sufficient to initiate and maintain all classes of v entricular hypertrophy. Myocardial and plasma renin and angiotensinogen wer e measured in rats during initiation and maintenance of ventricular hypertr ophy associated with DOCA implants and 1% NaCl drinking water, with and wit hout the AT(1) ANG II receptor blocker losartan. Additional groups of rats were given a low-sodium diet (0.04%) for 3 wk. Ventricular hypertrophy was initiated within 7 days and maintained for 35 days in DOCA-treated rats des pite significantly low myocardial and plasma renin, normal or low myocardia l and plasma angiotensinogen, or the presence of losartan. Furthermore, the re was no ventricular hypertrophy in low-salt diet-fed animals despite incr eased myocardial and plasma renin levels and normal angiotensinogen levels. Therefore, the myocardial RAS is not necessary to initiate or maintain car diac hypertrophy in DOCA-treated rats and is not sufficient to initiate car diac hypertrophy in low-salt diet-fed rats. Additionally, myocardial renin and angiotensinogen were significantly correlated with corresponding plasma levels.