Fig. 4. Effects of extracellular Ca²⁺ on ICC-MY Ca²⁺ transients.

A Colored heat-map image of total Ca²⁺ transients of antrum ICC-MY under control conditions with [Ca²⁺]_o = 2.5 mM and B after Ca²⁺ removal from the extracellular solution ([Ca²⁺]_o = 0 mM and 0.5 mM EGTA). Ca²⁺ activity is color-coded with warm areas (white, red) representing bright areas of Ca²⁺ fluorescence and cold colors (purple, black) representing dim areas of Ca²⁺ fluorescence. Scale bar is 50 mm in both A & B. C Ca²⁺ transients of firing sites in ICC-MY were color-coded and plotted as an occurrence map under control conditions with [Ca²⁺]_o = 2.5 mM. D showing the effects of reducing [Ca²⁺]_o to 0.5 mM Ca²⁺. E showing the effects of removal of [Ca²⁺]_o (final solution contain 0 mM Ca²⁺ and buffered with 0.5 mM EGTA). F–H Traces of Ca²⁺ PTCL activity in ICC-MY (PTCL area, blue and PTCL count, green) under control conditions F, in presence of 0.5 mM Ca²⁺ G and after removal of [Ca²⁺]_o as shown in H. Summary graphs of Ca²⁺ PTCLs in ICC-MY under control conditions and with reduced [Ca²⁺]_o to 1 mM, 0.5 mM and removal of [Ca²⁺]_o is plotted in I (PTCL area); J (PTCL count) and K (CTC frequency). Data were normalized to controls and expressed as percentages (%). Significance was determined using one-way ANOVA, **** = P < 0.0001, n = 6. All data graphed as mean ± SEM.