Fig. 6. Synchronisation of periodic Ca²⁺_[i] oscillations between fibroblasts is mediated by gap junction coupling. Spontaneous Ca²⁺_[i] oscillations in cultures of Fura-2-loaded myofibroblasts (A,C) and fibroblasts (B,D) were compared between contacting cells that were preselected for exhibiting coordinated periods. (A-B) Fura-2 Em₃₄₀/Em₃₈₀ ratios were recorded every 3 seconds over regions of interest including the entire cell and are here displayed for two contacting cells. During recording, gap junctions were uncoupled by adding 50 µM palmitoleic acid (PA) at the indicated time point. Arrows on top of the fluorescence profiles indicate how the position of Ca²⁺_[i] peaks of cell 2 (grey) develops over time in respect to the matched peak of cell 1 (black); dots indicate simultaneous oscillations of both cells and changing arrow lengths over time demonstrate desynchronisation of the two cells. (C,D) For statistical analysis, all matched period pairs obtained before addition of palmitoleic acid are displayed as longer period versus shorter period (above diagonal) and all data obtained after palmitoleic acid treatment are plotted as shorter period versus longer period (below diagonal). The mean of all period pairs obtained from two contacting cells is represented by the centre of an ellipse of which semi-major and semi-minor axes indicate s.d. Each cell pair is represented by one colour. Note that ellipses become larger and more distant from the diagonal in fibroblasts after gap junction inhibition, indicating uncoupling of Ca²⁺_[i] oscillations.