[Contractile function of the heart and its reactivity to noradrenaline in the process of the bodies adaptation to moderate altitudes].

In acute experiments on rats adapted for 4 weeks to the altitude of 2100 m it was found that at the early period of altitude adaptation the left ventricular systolic pressure and the maximal rates of pressure rise and fall considerably exceeded the values of control tests conducted in Moscow. Later on the parameters of the cardiac contractile function stabilized gradually. In 4 weeks the heart of adapted animals showed a greater increment of the contractility parameters in response to noradrenaline injection and a higher stability of the contractile function at very high heart rates.