[Comparative characteristics of the force and rate of myocardial contraction as indices of its contractility].

Experiments on papillary muscles of the cat heart have shown that the strength of contraction is a more adequate and sensitive criterion for evaluation of the effects of temperature, distension and contraction rate on myocardial contractility as compared to the strength of contraction. It is concluded that at the basis of the Starling law and chronoinotropic mechanisms there lies the contractility control exercised through changes in the contraction rate.