Variation with time (starting from the beginning of the TP-AGB phase) of the luminosity (top-left panel), temperature at the base of the envelope (top-right panel), core mass (bottom left) and mass-loss rate (bottom right) during the AGB phase of stars of metallicity Z = 0.03 (red squares) and Z = 0.04 (blue diamonds) of initial mass 4, 5, 6, 7 M_⊙. The points along the different tracks refer to the middle of the inter-pulse phase.