Fig. 2. (A , B ) Caffeine (50 mm)-induced and 4-chloro-m-cresol (4CmC) (400 μm)-induced Ca²⁺responses in CD19+ B cells in malignant hyperthermia-susceptible (MHS) (n = 11-13), malignant hyperthermia-negative (MHN) (n = 21), and control individuals (n = 18). Delta % fluo-3⁺cells are calculated as peak % fluo-3⁺cells-basal % positive cells. Caffeine-induced increases in [Ca²⁺]ⁱin B cells were significantly greater in MHS (n = 13) than in MHN (P = 0.0004) or control (P = 0.0001). The 4CmC-induced increases in [Ca²⁺]ⁱwere significantly greater in MHS (n = 11) than in controls (P = 0.003). There was no significant difference in 4CmC-induced changes in [Ca²⁺]ⁱbetween the MHS versus  MHN (P = 0.108). Bars = median. (C ) The correlation between the Ca²⁺response of B cells to caffeine (50 mm) and 4CmC (400 μm) in a total of 51 individuals, 11 MHS (closed square), 21 MHN (open square) and 18 control (open circle). There was a significant correlation between Ca²⁺response to caffeine and 4CmC (P < 0.0001). Patients who had mutations, Gly2434Arg , Arg2163His , Asp2431Asn , or Val2168Met  are indicated. The patient with Val2168Met  was III-3 in figure 3A. The test values from this patient in this figure were obtained from his first visit and slightly different from the values presented in figure 3B.