Regression of cardiac hypertrophy in cyp1a1ren‐2 transgenic rats

PURPOSE: To evaluate the usefulness of the cyp1a1ren-2 transgenic rat model of inducible hypertension for studies of the development and regression of cardiac hypertrophy. MATERIALS AND METHODS: Cyp1a1ren-2 rats received a diet containing 0% or 0.167% indole-3-carbinonl (I3C) for 4 weeks to induce hypertension. Cardiac magnetic resonance imaging (MRI) at 7 T was performed every second week for 10 weeks to measure left ventricular mass and the ejection fraction. Concomitantly, in six cyp1a1ren-2 rats blood pressure was recorded telemetrically. RESULTS: Plasma prorenin concentrations rose from 138 ± 38 to 15,490 ± 3990 ng/angiotensin I/mL/h (P < 0.001) in I3C-treated transgenic rats and returned to basal levels after cessation of I3C. Mean blood pressure increased to a plateau of 169 ± 11 mmHg by the second week of induction. After cessation of I3C (day 28), arterial pressure dropped to values slightly below those prior to induction within 4 days (basal: 106 ± 7 mmHg, day 32: 103 ± 21 mmHg; NS). At day 28, left ventricular mass was increased by 39% vs. 4% in controls (P < 0.001) without changes of the ejection fraction. Cardiac hypertrophy was completely reversed at day 70, as evaluated by MRI. CONCLUSION: The cyp1a1ren-2 transgenic rat is a useful model to study reversal and healing in the absence of surgical interventions.