The pathophysiological implications of aldosterone and adrenomedullin in the cardiac ventricular hypertrophy were examined. Male Sprague-Dawley rats were treated with deoxycorticosterone acetate (DOCA)-salt and monocrotaline (MCT) to selectively elicit left and right ventricular (LV, RV) hypertrophy, respectively. The mRNA expression of aldosterone synthase and adrenomedullin in LV and RV was determined by reverse transcription-polymerase chain reaction. The expression of aldosterone synthase and adrenomedullin was increased in LV, while not altered significantly in RV of DOCA-salt-treated rats. On the contrary, the expression was not significantly altered in LV, but increased in RV of MCT-treated rats. The enhanced expression of aldosterone synthase may be causally related with the development of ventricular hypertrophy, and the increased expression of adrenomedullin may act as a counter-regulatory mechanism.