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Revista do Instituto de Medicina Tropical de São Paulo

On-line version ISSN 1678-9946

Rev. Inst. Med. trop. S. Paulo vol.37 no.1 São Paulo Jan./Feb. 1995

http://dx.doi.org/10.1590/S0036-46651995000100009 

TRYPANOSOMIASIS

 

Cardiac b-receptors in experimental Chagas' disease

 

Receptores beta cardíacos na doença de Chagas experimental

 

 

Julio E. EndersI; Patricia PagliniI; Alicia R. FernandezI,II; Fernanda MarcoI; José A. PalmaI

ICátedra de Física Biomédica. Instituto de Fisiología. Facultad de Ciencias Médicas, Universidad Nacional de Córdoba
IIEstablished Investigator CONICET. Argentina

Correspondence to

 

 


SUMMARY

Experimental Chagas' disease (45 to 90 days post-infection) showed serious cardiac alterations in the contractility and in the pharmacological response to b adrenergic receptors in normal and T. cruzi infected mice (post-acute phase).
Chagasic infection did not change the b receptors density (78.591 ± 3.125 fmol/mg protein and 73.647 ± 2.194 fmol/mg protein for controls) but their affinity was significantly diminished (Kd = 7.299 ± 0.426 nM and Kd = 3.759 ± 0.212 nM for the control) p < 0.001. This results demonstrate that the alterations in pharmacological response previously reported in chagasic myocardium are related to a significantly less b cardiac receptor affinity. During this experimental period serious cardiac cell alterations take place and functional consequences will be detected in the chronic phase.

Keywords: Chagas' disease; b receptors.


RESUMO

Estudaram-se os receptores beta cardíacos de camundongos infectados pelo Trypanosoma cruzi na fase pós-aguda da doença de Chagas para estabelecer em que medida os mesmos contribuem a gerar respostas anômalas às catecolaminas observadas nestes miocardios. Utilizara-se 3-H/DHA para a marcação dos receptores beta cardíacos dos camundongos normais e dos infectados na fase pós-aguda (45 a 90 dias pós-infecção).
O número dos sítios de fixação foi similar nos dois grupos, 78.591 ± 3.125 fmol/mg. Proteína nos chagásicos e 73.647 ± 2.194 fmol/mg. Proteína no grupo controle. Em vez disso, a afinidade verificou-se significativamente diminuida no grupo chagásico (Kd = 7.299 ± 0.426 nM) respeito do controle (Kd = 3.759 ± 0.212 nM) p < 0.001.
Os resultados obtidos demonstram que as modificações observadas na estimulação adrenérgica do miocárdio chagásico se correlacionam com a menor afinidade dos receptores beta cardíacos e que estas alterações exerceriam uma parte determinante para as consequências funcionais que são detectadas na fase crônica.


 

 

Full text available only in PDF format.

Texto completo disponível apenas em PDF.

 

 

ACKNOWLEDGEMENTS

The authors thank Pr. D. Arce A. for allowing the use of the liquid scintillation counter.

 

REFERENCES

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Correspondence to:
Lic. Julio E. Enders
Cátedra de Física Biomédica. Facultad de Ciencias Médicas. Universidad Nacional de Córdoba
Santa Rosa 1085
C.P. 5000 - Córdoba - Argentina

Recebido para publicação em 27/06/1994.
Aceito para publicação em 10/10/1994.
This work was supported by a grant from SECyT. Universidad Nacional de Córdoba (R.D. 455/92).

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