Relationship of cardiac hemodynamic and biochemical adaptations to mortality during long-term aortic constriction

To determine the biochemical and hemodynamic responses to aortic ligation, and to assess the survival rate after the induction of hypertension, 90 normotensive rats were subjected to surgical constriction of the abdominal aorta. Mortality, left ventricular hemodynamics, myocardial biochemical assays, and plasma renin assays were determined 1 week, 1 month, 3 months, or 1 year later. Mortality was greatest between 1 week and 3 months after aortic ligation, during which plasma renin activity was significantly elevated. The rate of left ventricular pressure rise, contractile index, and myocardial alpha-adrenoceptor number were increased at 1 month, but were comparatively depressed at 3 months after the operation, suggesting that the heart was in failure at this time. At 1 year after ligation, hemodynamic and biochemical parameters continued toward normalization. Our data suggest that, in this rodent model, cardiac pump failure occurs through a combination of time-dependent, pressure-induced mechanical adaptations and myocardial biochemical changes that involve both the renin-angiotensin and sympathetic nervous systems. The observed relationship between mortality, myocardial hemodynamics, and biochemical parameters may be used for additional basic research investigations concerning the early periods of cardiac failure.