Changes in the cardiac beta-adrenergic system provoked by different T. cruzi strains.
BACKGROUND
It has been demonstrated that the beta-adrenergic signal transduction system is altered somewhere along its pathway in Trypanosoma cruzi infected hearts and we think that these alterations would differ according to the infection phase and the parasite strain. Their study would be important for the understanding of the disease's pathophysiology.


METHODS
In the present work we studied important components of this system in mice hearts infected with T. cruzi, Tulahuen strain and with SGO-Z12 isolate, obtained from a patient of an endemic area, in the acute phase of the infection, determining: the plasma catecholamines levels, the beta-receptors density and affinity as well as their function, the cardiac concentration of cAMP and the cardiac contractility as the physiologic response to the initial stimulus.


RESULTS
Plasma catecholamines levels were diminished in both infected groups when compared to the uninfected one (P < 0.01). The receptor's affinity was also diminished (P < 0.05) while their density was augmented only in the SGO-Z12 infected one (P < 0.01). The cAMP levels were higher in both infected groups (P < 0.01), the basal contractile force however increased only in the Tulahuen infected one (P < 0.01) while the response to catecholamines remained unchanged. The hearts infected with the SGO Z12 isolate presented an inferior response to epinephrine (P < 0.05) than the ventricles infected with the Tulahuen strain.


CONCLUSIONS
This model represents an important approach to understand the biochemical, physiological and molecular changes in the cardiac beta-adrenergic signalling that clearly begin in the acute phase of Chagas' disease and reveal a clear differentiation in the alterations produced by different parasite strains.
Lo Presti
M Silvina
MS
Cátedra de Física Biomédica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Santa Rosa 1085, 5000 Córdoba, Argentina.
Bustamante
Juan Manuel
JM
Rivarola
Walter H
WH
Fernández
Alicia R
AR
Enders
Julio E
JE
Fretes
Ricardo
R
Levin
Gloria
G
Paglini-Oliva
Patricia A
PA
D000818:Animals; D002395:Catecholamines / Q000097:blood*; D002598:Chagas Cardiomyopathy / Q000097:blood*; D000242:Cyclic AMP / Q000032:analysis; D004837:Epinephrine / Q000097:blood*; D006321:Heart / Q000503:physiopathology; D006801:Humans; D051379:Mice; D009206:Myocardium / Q000737:chemistry; D009638:Norepinephrine / Q000097:blood*; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000502:physiology
D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D009638:Norepinephrine; D004837:Epinephrine