Fig. 5

A–D Measurements of initial Δ[Mg²⁺]_i/Δt in four separate experiments at 35°C, in which Mg²⁺ efflux was induced by 140 mM extracellular Na⁺ (Ca²⁺-free Tyrode’s solution) at the times shown by the arrows. Estimated values of the initial Δ[Mg²⁺]_i/Δt (the slopes of the solid lines) are indicated near the traces. The cell was continuously illuminated by UV light throughout the run (~20 min) in the absence (A) and in the presence (B) of 20 µM KB-R7943. C The cell was intermittently illuminated, except for a 3-min period for the initial Δ[Mg²⁺]_i/Δt measurement with 20 µM KB-R7943 present throughout the run. D The Mg²⁺-loaded cell was treated with 20 μM KB-R7943 for 6 min in the Mg-loading solution (35°C), and then KB-R7943 was washed out by superfusion with NMDG Tyrode’s solution for 7 min before UV-illumination started for the initial Δ[Mg²⁺]_i/Δt measurement. EColumns a–e summarize relative Δ[Mg²⁺]_i/Δt estimated at 35°C with or without continuous UV-illumination (Cont. illum. − or +, respectively) and with various combinations of extracellular Ca²⁺ and KB-R7943 concentrations, as shown below each column. Columns a, b, c and e show results obtained from the experiments of the type shown in A, B, C and D, respectively. Columns represent mean ± SEM from 3–8 cells. **P<0.01 versus control (column a)