Fig. 6.

Removal of extracellular Ca²⁺ activates Cx43 hemichannels and causes extracellular release of GSH. (A) Difference in LY uptake among Cx43^+/+, Cx43^+/− and Cx43^−/− fibroblasts. Fibroblasts were exposed to either normal or Ca²⁺-free medium that contained 0.1% LY for 15 min. The cellular uptake of LY was photographed. (B) Cx43^+/+ fibroblasts were pre-treated with or without 3 mM heptanol, 100 μM lindane, or 200 μM suramin for 20 min. Cells were then exposed to normal or Ca²⁺-free medium that contained 0.1% LY for an additional 15 min (C) Difference in ATP release among Cx43^+/+, Cx43^+/− and Cx43^−/− fibroblasts. Fibroblasts were exposed to either normal or Ca²⁺-free medium for 15 min. ATP activity in culture supernatants was measured. Results shown are mean ± SE (n=5;* P<0.01). (D) Cx43^+/+ fibroblasts were pre-treated with or without 3 mM heptanol, 100 μM lindane, or 200 μM suramin for 20 min. Cells were then exposed to normal or Ca²⁺-free medium for 15 min. Supernatants were collected and assayed for ATP activity. Results shown are mean ± SE (n=4;* P<0.01; # P<0.05). (E) Difference in GSH release between Cx43^+/+ and Cx43^−/− fibroblasts. Fibroblasts were exposed to normal or Ca²⁺-free medium for 30 min (F) Cx43^+/+ fibroblasts were pre-treated with or without 3 mM heptanol, 100 μM lindane, or 200 μM suramin for 20 min. Cells were then exposed to normal or Ca²⁺-free medium for 30 min. GSH in culture supernatants were measured. Results are expressed as percentage of normal Ca²⁺ control (mean ± SE; n=4;* P<0.01; # P<0.05 vs. Ca²⁺-free control).