Experimental Chagas' disease: effects of propranolol upon cardiac beta-receptors.

Chagas' disease is an important cause of heart disfunction in Latin America. Previous works from our laboratory reproducing experimental Chagas' disease in mice, demonstrated that the affinity and density of cardiac beta-adrenergic receptors were altered during the acute, indeterminate and chronic phase in Albino Swiss mice inoculated with Trypanosoma cruzi. Keeping in mind that Propranolol is a beta-blocking agent that binds in the same receptors' site, which we have described as altered along T. cruzi infection. The present study was performed to determine if a beta-blocker treatment could prevent cardiac beta-receptors' disorders provoked by T. cruzi infection. Two different doses of Propranolol (9 and 40 mg/kg/day) were injected in the mice during 3 days; then they were infected with 7 x 10(4) parasites/mouse and propranolol was continued daily for one week. The results showed that the concentrations of propranolol used did not protect the beta-receptors' sites by administration of each doses.