[Myocardial contractility in newborn kittens under a physiologic loading regimen].

The angles of ramp of normalized dependences: "strength-velocity" and "terminal systolic length--terminal systolic strength" proved to be lesser under physiological loads in isolated papillary muscles of newborn kitten as compared with adult cats. Adrenaline increased the slope of these dependences up to the values characteristics of the adult cat's myocardium in saline. The data obtained suggest a low level of the calcium activation and ATPase activity of contractile proteins of the myocardium in newborn kitten.