Authors
I Barria2; J Guiza2; J Gonzalez2; J C Saez1; J L Vega2; 1 Pontificia Universidad Católica de Chile, Chile; 2 Universidad de Antofagasta, Chile Discussion
Introduction: Trypanosoma cruzi, the causative agent of Chagas disease induces repetitive cytosolic Ca2+ promoting T.cruzi invasion in cardiac cells. The aim of our study was to evaluate the role of pannexin-1 hemichannels(Panx1-HC) in repetitive cytosolic Ca2+ transients induced by T.cruzi in cardiomyocytes. Methods: Intracellular Ca2+ signal was evaluated by Ca2+ sensitive dye Fluo-3. The functional state of hemichannels was evaluated by dye uptake measurements in neonatal rat cardiomyocytes or HeLa cells stably transfected with Panx1 exposed to T.cruzi.The invasion was determinated by fluorescence imaging. Results: In cardiac cells, exposure to trypomastigotes evoked repetitive Ca2+ transients with a frequency of 0.026 +/- 0.004Hz similar to ATP-induced Ca2+ transient frequency of 0.038 +/- 0.003Hz. These effects were blocked by 10Panx1(100 uM) or probenecid (500 uM), which are Panx1-HC blockers. Exposure to trypomastigotes increased dye uptake 4 fold in cardiac myocytes, and 2 fold in HeLa-Panx1 cells compared to uninfected cells. This phenomenon was completely prevented by 10Panx1(100uM). The invasion was significantly blocked by 10Panx1 to 1.3% infected cells vs 16% infected cells under control conditions. Discussion: These results provide evidence that T.cruzi induced opening of Panx1-HC promotes signaling events that favor invasion in cardiac tissues. 
