title: Active force during hypoxia of hypertrophied rabbit right ventricular trabeculae.
abstract: Hypertrophy is often accompanied by increased myocardial oxygen demand, but any unique effects of hypoxia on contraction in hypertrophy are unknown. Trabeculae from normal [n = 9; 0.119 +/- 0.014 mm2 (means +/- SE) cross-sectional area] and hypertrophied (pulmonary artery constriction; n = 7; 0.108 +/- 0.028 mm2) rabbit right ventricles were subjected to graded hypoxia (Krebs-Ringer solution, 28 degrees C, 1 Hz stimulus frequency). During normoxia, peak active isometric (Pmax) and resting stress (Prest) at optimum length and peak rate of stress development (dP/dt) in hypertrophy were the same as normal and time to peak stress was longer than normal. Time to peak stress and dP/dt decreased with hypoxia, but time to peak stress remained longer than normal in hypertrophy; Prest was unchanged. The ratio of peak active stress (P) during hypoxia to Pmax decreased linearly with superfusate PO2, but the hypertrophy relationship (y = 4.00 X 10(-3) x + 0.084) is the same as normal (y = 3.70 X 10(-3) x + 0.154; p greater than 0.05). Therefore, a normal level of P was preserved in hypertrophied myocardium and prolonged time to peak stress might have been important for that preservation.
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology; D009929:Organ Size; D011817:Rabbits