Fig. 7. The role of Ca²⁺ in K⁺-sensitive luminescence. Results are expressed as 200 s integrated luminescent response to stimulation by addition of indicated volume of low (7.5 µmol l^-1) or high (108 µmol l^-1) [K⁺] solutions. (A) K⁺ stimulation following 40-50 min treatment with 5 µmol l^-1 BAPTA-AM (open bar) or control solution (filled bar) (N=5-6 for each treatment/stimulus combination tested). (B) K⁺-stimulation of Ca-free cell suspensions with (filled bar) or without (open bar) simultaneous replacement of Ca²⁺ in stimulating solution (N=5 for each stimulus tested). n.d.=not determined. Values are means ± S.D.