Figure 2.

Effects of proximity to the edge of the preparation on recovery of responses and effects of re-cutting the edges of the preparation. Recordings were made alternately from smooth muscle cells 1 mm (filled circles) or 4 mm from the edge of the tissue (open circles) after initial set up and after re-cutting both sides of the preparation. Symbols represent averaged responses in 10 min bins, in order to display clearly the similar time courses for cells at 1 and 4 mm. (A) The IJP increased in amplitude from t = 0, with similar time course for cells 1 mm (black dots) or 4 mm (gray squares) from the edge of the preparation (n = 4). Edges were re-cut at the vertical dashed line. (B) IJPs were significantly reduced immediately after the cut, but not to the level after the initial setup. (C) The amplitude of IJPs (mean + standard deviation) was negligible immediately following dissection, and recovered after 120 min in cells at both 1 and 4 mm (averaged over 30 min periods). Mean responses decreased significantly after the edges were re-cut. There were no significant differences between cells 1 vs. 4 mm from the edge of the preparation at any point (n = 4). (D–F) Equivalent changes in numbers of dye coupled cells after standardized intracellular injection of carboxyfluorescein dye. Note the drop in coupling after the sides of the preparation were re-cut. These results show that both the initial set-up procedure and the act of cutting the edges of the preparation, affects cells at different distances equally.