Functional reserve of the heart and catecholamines in experimental mitral valve incompetence

In dogs with experimental mitral valve incompetence, by the end of the adaptation stage (2nd week) the cardiac functional reserve decreases; the decrement is correlated with the exhaustion of the reserve of catecholamine synthesis evident from the decrement of their precursors in the myocardium and adrenals as well as from the destruction of plentiful cells of the adrenal medulla, accompanied by development of necrosis, dystrophy, and disturbances of vascular permeability in the adrenal glands. In the initial period of the compensatory stage (1st month) a considerable activation of the catecholamine synthesis takes place, together with their increase in the right ventricular myocardium and in the adrenals.