Figure 8.

Mitochondrial Ca²⁺ uptake and release fluxes measured under voltage clamp. (A) Fluxes measured from a representative cell under voltage clamp after depolarization from −70 to −10 mV with a Na⁺-free pipette solution, before (J_cont) and after exposure to 1 μM FCCP (J_FCCP-res). The FCCP-sensitive flux (J_FCCP-sens, thin trace), calculated as the difference between the total flux measured in the absence (J_cont) and presence of FCCP (J_FCCP-res), is positive and increases steeply with [Ca²⁺]_i, much like the CGP-resistant flux seen in cells after high K⁺ depolarization. Cell ma4980. (B) Flux measurements from another cell during the recovery after a step from −70 to −10 mV (pipette solution contained 6.5 mM NaCl) before and after exposure to CGP (1 μM). The CGP-sensitive flux (thin trace), calculated as the difference between the total flux in the absence and presence of CGP, is inward and biphasic, similar to J_CGP-sens observed in cells depolarized with high K⁺. Cell sc0w21.