Trypanosoma cruzi (CL strain) infection in mice changes the chronotropic effect of isoproterenol in vitro.

Cardiac autonomic denervation has been reported to occur in experimental T. cruzi infection. We used isoproterenol (IP) to investigate the in vitro chronotropic sensitivity of atrial beta-adrenoceptors from mice acutely (30 days) or chronically (180 days) infected with T. cruzi, CL strain (a myotropic strain). Displacement of the dose-response curve to IP to the right occurred in the acute phase group. In the chronic phase group the opposite effect occurred (hyperreactivity to IP) although to a lesser extent. These results suggest that infection of mice with this strain of T. cruzi induces quantitative or qualitative changes in atrial beta-adrenoceptors.