Fig. 6. UTP-mediated calcium responses in connexin-transfected HeLa cells. Cells were loaded with fura-2, exposed to 1 µM UTP, and ratio imaging was performed. Single cell calcium traces were constructed as above. HeLa/Cx45 transfectants exhibited asynchronous calcium oscillations similar to the parent HeLa cells. In contrast HeLa/Cx43 transfectants displayed a calcium rise that was followed by a gradual decline to baseline without much oscillatory behavior. HeLa/Cx46 transfectants displayed dampened oscillatory behavior.