Figure 3.

[ATP]_m increase triggered by KCl challenge of primary cultures of myotubes. (A) Myotubes were perfused with glucose as metabolic substrate. Simultaneous [Ca²⁺]_m changes triggered by KCl are also shown (gray trace). (B) Perfusion of myotubes with pyruvate and lactate instead of glucose increases both kinetics and peak value of the [ATP]_m rise. (C) Pretreatment of myotubes with atractyloside (40 μM) reduces the KCl-induced [ATP]_m rise. Throughout the experiments shown in this figure, cells were perfused in Krebs–Ringer buffer with pyruvate and lactate as metabolic substrate.