From dietary glucose to liver glycogen: the full circle round.

PERSPECTIVES AND SUMMARy 52 HISTORICAL BACKGROUND 53 Physiological Studies . . . . . ... . . . . . . . . ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . ...... . . . . . . .. . . . . . 53 Biochemical Studies . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . 54 EMERGENCE OF THE GLUCOSE PARADOX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 ATTEMPTS TO RESOLVE THE PARADOX . . . . . . . . . . . 56 Experiments in Animals. . . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . .. . . . . . . .... . . . . 57 Experiments in Humans . . . . . 61 A Noninvasive Approach . . . . . . . . . . . . . . . . . . . . .. ... . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .... . . 62 UNRESOLVED PROBLEMS..... . 63 Why Is Glucose Not Used Efficiently by the Liver? ... . . . 63 1s Glucose-6-phosphatase Under Metabolic Control? 66 The Fructose-2, 6-bisphosphate Paradox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Where Does the Glucose-to-Lactate Conversion Take Place? ... .. . . . . . . . . .. . . . . . . ... . . . 67 Is There an Advantage to the Indirect Pathway? . ......... . . . . . . . . . . . . . . . . 68 CAN THE OLDER AND NEWER FlNDINGS BE RECONCILED? 68 IN RETROSPECT ..... . . .... . . . . . . . . . . . . . . . . . 69