Developed pressure data may provide misinformation when used alone to evaluate systolic function in isovolumetric left ventricle preparations.
We report data showing that developed pressure (DPmax) may lead to opposite conclusion with respect to maximal developed circumferential wall stress (sigma max) when used to assess contractile function in left ventricle isovolumic preparations. Isovolumetric left ventricle preparations of rats with cardiac hypertrophy (H; N = 10) induced by isoproterenol administration showed higher DPmax (174 +/- 14 mmHg) than control (C; N = 8) animals (155 +/- 12 mmHg) or rats with regression (R; N = 8) of hypertrophy (144 +/- 11 mmHg). In contrast, the estimated sigma max for C (145 +/- 26 kdynes/cm2) and R (133 +/- 17 kdynes/cm2) was higher than for H (110 +/- 13 kdynes/cm2). According to Laplace's law, the opposite results of DPmax and sigma max may depend on the increased mass/volume left ventricle ratio of the hypertrophied hearts, which favored pressure generation. These results clearly show that DPmax should be used with caution to analyze systolic function.
Murad
N
N
Departamento de Fisiologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brasil.
Tucci
P J
PJ
D000818:Animals; D001795:Blood Pressure Determination; D006332:Cardiomegaly / Q000139:chemically induced; D002316:Cardiotonic Agents / Q000009:adverse effects; D007545:Isoproterenol / Q000009:adverse effects; D009200:Myocardial Contraction; D051381:Rats; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left
D002316:Cardiotonic Agents; D007545:Isoproterenol