Fig. 3. Effect of coexpressing both the R3893C and D4505H variants together with wild-type (WT) type 1 ryanodine receptor (RYR1 ) in dyspedic myotubes on the caffeine sensitivity of sarcoplasmic reticulum Ca2+release. Representative caffeine concentration responses in dyspedic myotubes expressing wild-type RYR1 alone (n = 34) (A) , R3893C+ D4505H (n = 25) (B) , and WT RYR1 +R3893C-D4505H (n = 14) (C) . Average (± SEM) caffeine concentration-response curves for the conditions shown in A–C (D) .