Force-velocity-length relationship during cardiac hypertrophy. Time course of activation.
Basic mechanical properties observed during cardiac hypertrophy were studied in left ventricular rat papillary muscles after exposure to chronic pressure and/or volume overloading. It is always possible, during such overloading conditions, to define the level of contractility in terms of a force-velocity-length (F-V-L) relationship regardless of time and initial length. Thus, during a determined period of the contraction phase and for a given total load, shortening velocity remained an univocal time-invariant function of shortening length, involving a time-independent maximum intensity of activation. The onset of this precise phase was reached relatively soon after stimulus. The time-independent F-V-L relation was observed both in controls and in hypertrophied heart muscles, whatever the degree and the type of induced hypertrophy, and even during the latest phases of congestive heart failure.
D000818:Animals; D006332:Cardiomegaly / Q000503:physiopathology*; D003250:Constriction; D006333:Heart Failure / Q000503:physiopathology*; D009200:Myocardial Contraction; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors