title: Studies of membrane fluidity and heart contractile force in Trypanosoma cruzi infected mice.
abstract: In Chagas disease serious cardiac dysfunction can appear. We specifically studied the cardiac function by evaluating: ventricle contractile force and norepinephrine response, affinity and density of beta-adrenergic receptors, dynamic properties of myocardial membranes, and electrocardiography. Albino swiss mice (n = 250) were infected with 55 trypomastigotes, Tulahuen strain and studied at 35, 75, and 180 days post-infection, that correspond to the acute, indeterminate, and chronic phase respectively. Cardiac beta-adrenergic receptors' affinity, myocardial contractility, and norepinephrine response progressively decreased from the acute to the chronic phase of the disease (p < 0.01). The density (expressed as fmol/mg.prot) of the receptors was similar to non-infected mice (71.96 +/- 0.36) in both the acute (78.24 +/- 1.67) and indeterminate phases (77.28 +/- 0.91), but lower in the chronic disease (53.32 +/- 0.71). Electrocardiographic abnormalities began in the acute phase and were found in 65% of the infected-mice during the indeterminate and chronic phases. Membrane contents of triglycerides, cholesterol, and anisotropy were similar in all groups. A quadratic correlation between the affinity to beta-adrenergic receptors and cardiac contractile force was obtained. In conclusion the changes in cardiac beta-adrenergic receptors suggests a correlation between the modified beta-adrenergic receptors affinity and the cardiac contractile force.
authors.affiliation: Cátedra de Física Biomédica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Santa Rosa 1085, 5000 Córdoba, Argentina. jenders@fcm.unc.edu.ar
authors.forename: Julio E
authors.initials: JE
authors.lastname: Enders
authors.forename: A Ruth
authors.initials: AR
authors.lastname: Fernández
authors.forename: Héctor W
authors.initials: HW
authors.lastname: Rivarola
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Paglini
authors.forename: José A
authors.initials: JA
authors.lastname: Palma
mesh_terms: D000208:Acute Disease; D000818:Animals; D002598:Chagas Cardiomyopathy / Q000378:metabolism / Q000503:physiopathology; D014355:Chagas Disease / Q000378:metabolism / Q000503:physiopathology*; D002908:Chronic Disease; D004195:Disease Models, Animal; D004562:Electrocardiography; D008297:Male; D008560:Membrane Fluidity; D051379:Mice; D009200:Myocardial Contraction; D009638:Norepinephrine / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000472:pathogenicity*
chemical_list: D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine