Signals for the remodeling of the cardiac interstitium in systemic hypertension.

Cardiac myocyte growth is the common denominator in myocardial hypertrophy irrespective of the hypertrophic stimulus. The hypertrophic remodeling of the myocardium may or may not also include the growth of nonmyocyte cells, thereby creating the potential for heterogeneity in tissue growth. Hypertrophy, therefore, need not be a uniform process, especially if trophic factors responsible for myocyte and nonmyocyte growth are independent of one another. To examine this hypothesis further, we determined the relative importance of hemodynamic and hormonal factors in augmenting ventricular mass and cardiac fibroblast-induced collagen accumulation in several rat (Sprague-Dawley) models of arterial hypertension: renovascular hypertension (RHT), infrarenal aorta banding (IRB), and chronic aldosterone (ALDO) administration. Elevations in arterial pressure were comparable in each, whereas circulating angiotension II (Ang II) and ALDO were dissimilar: in RHT, each was increased; with IRB they were normal; and with chronic ALDO, Ang II was suppressed whereas ALDO was increased. We reasoned that because of the in-series arrangement of the ventricles, where only the left ventricle (LV) experienced an elevation in systolic pressure, the right ventricle (RV) served as a negative control regarding hemodynamic factors. Relative to the in-parallel arrangement of the ventricles, provided by the coronary circulation, the RV served as a positive control for circulating hormones.(ABSTRACT TRUNCATED AT 250 WORDS)