Figure 5.

Effects of prestimulation of HeLa cells with histamine on the subsequent response of [ATP]_m and [ATP]_c to a change in metabolic substrate (A and B). Shift from glucose to pyruvate and lactate as metabolic substrate in the perfusion medium produces a transient rise in [ATP]_m (mtLuc) and [ATP]_c (cytLuc) (A) that is increased when cells are stimulated previously with histamine (100 μM) (B), while no further changes in [Ca²⁺]_m are observed (mtAEQ). (C) Substrate-induced [ATP]_m peak maximum as a function of time after histamine removal.