EFFECTS OF HYPOXIA ON GLUCOSE METABOLIC PATHWAYS IN THE MEALWORM LARVAL FAT-BODY IN-VITRO - ALTERATIONS OF HORMONAL ACTIONS

Glucose metabolism of mealworm larval fat body tissue in vitro was stu died using a highly sensitive micro-radiorespirometric method. Respira tory O-2 partial pressure variations were used to measure catabolic ra tes of[1-C-14]glucose or [6-C-14]glucose molecules as substrates when introduced separately into the fat body incubation medium. Expired vol umes of CO2 and (CO2)-C-14 radioactivity were determined when fat body was submitted to gradual hypoxia. The modifications in the specific r adioactivity kinetics and in the cumulative yields of total (CO2)-C-14 derived from [1-C-14]glucose and [6-C-14]glucose molecules under grad ual hypoxia, were measured. Catabolic corpora cardiaca hormonal extrac ts from Tenebrio strongly inhibited the utilization of the pentose cyc le in the in vitro degradation of fat body glucose, when the respirato ry gaseous mixture contained 30% O-2 This effect was drastically reduc ed when fat body underwent hypoxia (5% O-2) The anabolic insulin-like peptide (ILP) from Tenebrio strongly stimulated the utilization of the pentose cycle in the in vitro degradation of fat body glucose when th e respiratory gaseous mixture contained 30% O-2; this dose-dependent e ffect was increased when fat body underwent hypoxia (5% O-2). (C) 1997 Elsevier Science Inc.