[Catecholamine concentration and adenyl cyclase and phosphodiesterase activities of the sarcolemma of myocardial cells during hypokinesia and in experimental information neuroses].

Restriction of motor activity and motor-alimentary conditioning in dogs reduced the adrenaline (A) and noradrenaline (NA) contents in the myocardium, dopamine, too, revealing a tendency to reduction. Basal activity of the sarcolemma adenylate cyclase (AC), its sensitivity to A, NA and NaF did not change as well as the basal activity of sarcolemma phosphodiesterase (PDE) and its sensitivity to the inhibitory effect of high concentrations of Ca2 (10(-4) M). In experimental informational neurosis, NA content in the myocardium increased 5-fold compared to control values, the dopamine content also increasing. Basal activity of the sarcolemma AC did not change whereas its sensitivity to NA and to activating effect of NaF decreased. Basal activity of PDE increased and its sensitivity to Ca2 effect decreased in this condition. The increase of PDE activity and increase of its sensitivity to the inhibitory effect of high concentrations of Ca2+ in combination with desensitization of the regulatory subunit AC to NA followed by changes in its catalytic subunit, seem to lead to a decrease of cAMP content and cAMP-dependent phosphorylation in cardiomyocyte that may underlie the Ca2+ transport disturbance observed in informational neurosis, and reduction of contractility of the contractile protein system. Heart pressure overload, caused in informational neurosis by the stable arterial hypertension may play an important role in the genesis of this reduction.