Trypanosoma cruzi: Increased 5 '-nucleotidase activity associated with dysfunction of adrenergic receptors in acutely infected albino Swiss mice

Adenosine, derived from hydrolysis of 5'-AMP by 5'-nucleotidase activity, m ay be involved in coupling coronary blood flow to cardiac function and meta bolism; it has been postulated as a cardioprotective substance in ischemic myocardium. The stimulation of beta-adrenergic receptors produces an increa se in adenosine by 5'-AMP hydrolysis. In addition, it has been demonstrated that in Chagas' disease there is decreased cardiac perfusion. We show in t his paper by histochemical and densitometric procedures that ecto-5'-nucleo tidase activity increases in ventricles of acutely Trypanosoma cruzi-infect ed mice and that the density of beta-adrenergic receptors is significantly diminished with affinity similar to controls. showing that a compensatory m echanism was absent. The increase of ecto-5'-nucleotidase in heart myocytes from infected mice may produce cardioprotective adenosine that may be inde pendent of beta-adrenergic function, based on the hypoperfusion conditions of acute chagasic cardiomyopathy.