Figure 2.

Wave progression in confluent astrocytic monolayers and across cell-free lanes. The distance of the wave front (F/Fo>1.15) from the point of stimulation was measured in images taken at 1-sec intervals. The symbols indicate the measured distance; the solid curves are the least-squares best fit to an exponential function. The traces have been shifted vertically for clarity. The first three time points following initiation of the calcium wave were not included; the waves continued beyond the microscope field in each case. The tick marks on the y axis represent 100 μm distances. (A) Three representative traces of waves in confluent monolayers are shown. Although the wave velocity tends to decline gradually with distance, each wave showed occasional, brief pauses at cell boundaries. (B) Three representative traces of waves crossing cell-free lanes are shown. The rises in calcium progressed at a relatively constant rate until they reached the lane, in which no calcium signal could be seen. The wave reappeared on the far side of the lane after an interval that increased with lane width. (Lane widths and locations are indicated on the traces.) Since the waves reappeared a short distance beyond the edge of the lane, the jumps in distance are larger than the lane widths.