Cardiac autonomic denervation and functional response to neurotoxins during acute experimental Chagas' disease in rats

Severe cardiac autonomic denervation occurs in the acute Chagas' disease in rats. The present study aims at verifying whether this denervation was acc ompanied by impairment of heart function. Scorpionic (Tityus serrulatus) cr ude venom was used for neurotransmitter release in isolated hearts (Langend orff's preparation). In control hearts. the venom induced significant brady cardia followed by tachycardia. In infected animals, despite the severe (sy mpathetic) or moderate (parasympathetic) cardiac denervation, the venom pro voked similar bradycardia but the tachycardia was higher. The hearts of inf ected animals beat at significantly lower rate. Atropine prevented this low er rate. Our results demonstrated sympathetic dysfunction during the acute phase of Trypanosoma cruzi infection in rats, the parasympathetic function being spared. (C) 2001 Elsevier Science B.V. All rights reserved.