Fig. 3. Cytosolic Ca²⁺ signals evoked by 1 mM caffeine in ^wtRyR3- and ^V2322DRyR3-expressing HEK293 cells. (A,B) Ca²⁺ responses and the corresponding first differentiate dA/dt of ^wtRyR3- (continuous line) and ^V2322DRyR3-expressing (dotted line) HEK293 cells stimulated with 1 mM caffeine as indicated by the black horizontal bar. (C,D) Ca²⁺ transients in ^V2322DRyR3-expressing HEK293 cells were characterised by a larger amplitude and a faster rate of rise than in ^wtRyR3-expressing cells. Amplitude (A) expressed as % F/F: 77.6±8.8, n=62 versus 140.0±15.2, n=48 in the ^wtRyR3- and ^V2322DRyR3-expressing cells (P<0.001), respectively. Rate of rise (dA/dt): 71.4±8.1, n=62 versus 107.6±11.9, n=48 in the ^wtRyR3- and ^V2322DRyR3-expressing HEK293 cells (P<0.01), respectively.