Statistical analysis of effect of anoxia on rate of change of ventricular pressure.

Hearts from 32 male Sprague-Dawley rats were studied to determine effects of anoxia on ventricular contractility. Maximum rate of ventricular pressure changes with time (Pmax) were obtained from simultaneous recordings of right and left ventricular pressure curves. Peak aortic flow and heart rate were measured. Anoxia was produced by 100% N2 respiration. Statistical models were repeated-measures analysis of variance and randomized block factorial analysis of variance. Alpha was 0.05. Heart rate during anoxia was significantly lower than during the 1st min of recovery. Heart rate during both these periods was significantly lower than in preanoxia or the remainder of recovery. Peak aortic flow was not significantly altered. In left ventricles positive Pmax was significantly higher than negative Pmax. In right ventricles positive and negative Pmax were not significantly different. Left ventricular Pmax was significantly depressed during anoxia, whereas right ventricular Pmax was not. Significant differences in pressure developed per mass of tissue was a possible source of variation in right (0.12 +/- 0.002 mmHg/mg) and left (0.16 +/- 0.009 mmHg/mg) ventricular contractile maintenance.