Figure 5.

PMCA mediates Ca²⁺ extrusion following high-pH stimuli in HOB cells. (A–C) Representative traces for pH 8 (black boxes)-induced [Ca²⁺]_i increases, in the absence of 100 μM caloxin 1b1 and 10 μM CE (A), with 100 μM caloxin 1b1 (white box at the top) (B), or with 10 μM CE (white box at the top) (C), in the presence of extracellular Ca²⁺ (white boxes at bottom in A to C). (D) Peak values of [Ca²⁺]_i during high-pH stimulation in the absence of 100 μM caloxin 1b1 and 10 μM CE (open column; 1.15 ± 0.01 F/F₀ units), with 100 μM caloxin 1b1 (upper gray column; 1.15 ± 0.02 F/F₀ units), and with 10 μM CE (lower gray column; 1.07 ± 0.01 F/F₀ units). Each column denotes the mean ± SE from 6, 3, and 4 independent experiments, respectively. (E) Ca²⁺ extrusion rates during high-pH stimulation in the absence of 100 μM caloxin 1b1 and 10 μM CE (open column; 55.6 ± 3.0%), with 100 μM caloxin 1b1 (upper gray column; 32.4 ± 8.5%), and with 10 μM CE (lower gray column; 29.0 ± 4.4%). Each column denotes the mean ± SE from 6, 3, and 4 independent experiments, respectively. Statistically significant differences (in (D,E)) between columns (shown by solid lines) are indicated by asterisks. * P < 0.05.