Fig. 2. Effect of caffeine and A23187 on Ca²⁺ efflux from non-permeabilised ^wtRyR- and ^V2322DRyR3-expressing HEK293 cells. (A) ⁴⁵Ca²⁺ efflux was measured in ^wtRyR3 (squares) and ^V2322DRyR3-expressing cells (circles) in Ca²⁺-free medium. After 8 minutes, cells were challenged for 2 minutes with 10 mM caffeine. (B) The total-releasable Ca²⁺ was measured by challenging the cells with 10 µM A23187 in ^wtRyR3- (squares) and ^V2322DRyR3-expressing cells (circles) in the same medium. The results are plotted as fractional loss as a function of time. Representative traces from five independent experiments are shown. Data points are given as mean±s.d.