Fig. 5. Coordination of Ca²⁺ oscillations increase with the increase of agonist concentration in connected hepatocytes. Hepatocytes were loaded or injected with fura2. The figures show successive measures of [Ca²⁺]_i in the same hepatocyte triplet. Cells were sequentially stimulated with increasing concentrations of noradrenaline (0.02, 0.05 and 0.1 µM) for the time shown by the horizontal bars. Addition of the lowest dose of noradrenaline to the bath was followed by oscillations in the three cells that were not coordinated (left). After washing, addition of a higher concentration of noradrenaline (0.05 µM) induced coordinated Ca²⁺ oscillations (middle part). Finally, very well coordinated oscillations were observed in the presence of 0.1 µM noradrenaline (right). The same results were obtained in hepatocyte doublets and are representative of those obtained using 12 triplets and 21 doublets in five independent experiments. Recording of the traces was interrupted during the washing process (5 minutes).