Fig. 5. Ryanodine decreases the KCl-evoked [Ca²⁺]^cyttransient. Cells were stimulated two consecutive times with 200 mm KCl in the absence (A ) and presence (B ) of 200 μm ryanodine (Ry). The application of ryanodine was started 5 min before the first KCl stimulation, and KCl was applied for 2 min. The time interval between the first and second KCl pulse was 18 min. When cells were exposed to ryanodine, the initial response was an increase in the [Ca²⁺]^cyt(indicated with an arrow ). (C ) The mean peak values for the first and the second KCl-evoked [Ca²⁺]^cyttransients in the absence (open circles ) and presence (filled circles ) of ryanodine. Asterisk  and number sign  indicate a statistically significant difference (P < 0.02 and P < 0.05, respectively; unpaired t  test) between control and ryanodine groups.