Figure 6.

The presence of inflammatory interferon (IFN)-γ⁺ and interleukin (IL)-4⁺ cells in the cardiac tissue and heart damage characterized by creatine kinase cardiac isoenzyme MB (CK-MB) activity in serum, loss of connexin 43 and electrocardiographic (ECG) abnormalities in C57BL/6 and pfp^−/− mice at 150 days postinfection. (a) IFN-γ⁺ and IL-4⁺ cells invading heart tissue during chronic Trypanosoma cruzi infection. (b) The relative frequencies of IFN-γ⁺ cells among total inflammatory mononuclear cells and CD8⁺ cells are shown. (c) Cardiomyocyte damage was evaluated by CK-MB activity in serum samples from chronically infected C57BL/6 (black circle) and pfp^−/− (white circle) mice in comparison with the non-infected mice (black/white triangles). (d) The pattern of connexin 43 characterizing intercalary discs of cardiomyocytes was analysed in non-infected and chronically infected C57BL/6 and pfp^−/− mice. Quantification of the distance between intercalary discs of cardiomyocytes revealed as connexin 43 cluster labelling in T. cruzi-infected C57BL/6 (black circle) and pfp^−/− (white circle) mice in comparison with the non-infected mice (black/white triangles). Each value represents an individual mouse. The data are representative of two or three experiments. (e) ECG recordings from non-infected and T. cruzi-infected C57BL/6 and pfp^−/− mice; * and Δ represent second-degree atrioventricular block and sinusal arrhythmia respectively. Representative records from 5–10 analysed animals per group. **P< 0.01comparing non-infected vs. T. cruzi-infected mice; ^#P< 0.01 comparing the wild-type vs. the pfp^−/−T. cruzi-infected mice.