Figure 11.

Spontaneous whole-cell Ca²⁺ transients are replaced by Ca²⁺ waves when changes of the plasma membrane potential are suppressed A, superfusion of a spontaneously beating ESdC with depolarizing high-K⁺ solution resulted in the suppression of whole-cell Ca²⁺ transients but lead to the appearance of Ca²⁺ waves. B, confocal linescan image of an electrically coupled cell pair and the F/F₀ plot averaged over the entire width of the lower ESdC. Superfusion of the cell with low-Na⁺ solution suppressed whole-cell Ca²⁺ transients (*) that were synchronized between the two adjacent cells. Spontaneous release events transitioned into Ca²⁺ waves (•) that were confined to the boundaries of the individual cell. C, Ca²⁺ waves in the presence of LiCl-containing (n = 5) and KCl-containing solution (n = 1) could be distinguished from whole-cell Ca²⁺ transients under control conditions (n = 3) because of their significantly reduced upstroke velocity (P < 0.05).