Augmented right ventricular function in systemic hypertension-induced hypertrophy

Abstract

The contractile properties of right ventricular papillary muscles from the hearts of 15 rats which had developed hypertension 6 weeks following renal artery ligation were compared with those from 14 normal litter-mates. In the experimental group, the heart weight–body weight ratio was increased by 39%, while the right ventricular weight–body weight ratio increased 20%. Right ventricular papillary muscles from the hypertensive rats demonstrated increased tension development at the apex of the length-active tension curve (P < 0.0001), elevated maximal rate of tension development (P < 0.001), and increased maximal velocity of contraction at muscle lengths corresponding to both a light preload and at Lmax (P < 0.05). Resting tension and time-to-peak tension in the muscles from the hypertensive group were not significantly different from the normal group. Thus, improved right ventricular performance, in the presence of increased left ventricular afterload, may indicate the existence of a stimulus to increased function in hyper-trophied muscle not yet negated by the adverse effects of direct exposure to stress.