Lactate concentration versus volume dependence in R3327-AT tumors. In rats 3, 4, 6, 7, 8 and 10 (open symbols) the lactate concentration reached a maximum at the tumor volume of 1000–1500 mm3, while in rats 1, 2, 5 and 9 (filled symbols) the lactate either increased or increased and reached a plateau in this volume interval. Shaded areas indicate ranges of volume Groups 1–5.