Heart rate responses to a muscarinic agonist in rats with experimentally induced acute and subacute chagasic myocarditis
Rev. Inst. Med. Trop. Säo Paulo
;
42(4): 219-24, July-Aug. 2000. tab, graf
Artículo
en Inglés
| LILACS
| ID: lil-266055
RESUMO
We administered arecoline to rats, with experimentally induced chagasic myocarditis, in order to study the sinus node sensitivity to a muscarinic agonist. Sixteen month old rats were inoculated with 200,000 T. cruzi parasites ("Y" strain). Between days 18 and 21 (acute stage), 8 infected rats and 8 age-matched controls received intravenous arecoline as a bolus injection at the following doses 5.0, 10.0, 20.0, 40.0, and 80.0 mug/kg. Heart rate was recorded before, during and after each dose of arecoline. The remaining 8 infected animals and 8 controls were subjected to the same experimental procedure during the subacute stage, i.e., days 60 to 70 after inoculation. The baseline heart rate, of the animals studied during the acute stage (349 Ý 68 bpm, mean Ý SD), was higher than that of the controls (250 Ý 50 bpm, p < 0.005). The heart rate changes were expressed as percentage changes over baseline values. A dose-response curve was constructed for each group of animals. Log scales were used to plot the systematically doubled doses of arecoline and the induced-heart rate changes. The slope of the regression line for the acutely infected animals (r = - 0.99, b =1.78) was not different from that for the control animals (r = - 0.97, b = 1.61). The infected animals studied during the subacute stage (r = - 0.99, b = 1.81) were also not different from the age-matched controls (r = - 0.99, b = 1.26, NS). Consequently, our results show no pharmacological evidence of postjunctional hypersensitivity to the muscarinic agonist arecoline. Therefore, these results indirectly suggest that the postganglionic parasympathetic innervation, of the sinus node of rats with autopsy proved chagasic myocarditis, is not irreversibly damaged by Trypanosoma cruzi.
Texto completo:
Disponible
Índice:
LILACS (Américas)
Asunto principal:
Arecolina
/
Nodo Sinoatrial
/
Cardiomiopatía Chagásica
/
Agonistas Muscarínicos
/
Frecuencia Cardíaca
Límite:
Animales
Idioma:
Inglés
Revista:
Rev. Inst. Med. Trop. Säo Paulo
Asunto de la revista:
Medicina Tropical
Año:
2000
Tipo del documento:
Artículo
País de afiliación:
Argentina
/
Venezuela
Institución/País de afiliación:
Universidad de Los Andes/VE
Similares
MEDLINE
...
LILACS
LIS