Effects of Hypoxia on Glucose Metabolic Pathways in the Mealworm Larval Fat Body In Vitro: Alterations of Hormonal Actions

Abstract

Glucose metabolism of mealworm larval fat body tissue in vitro was studied using a highly sensitive micro-radiorespirometric method. Respiratory O2 partial pressure variations were used to measure catabolic rates of [1-14C]glucose or [6-14C]glucose molecules as substrates when introduced separately into the fat body incubation medium. Expired volumes of CO2 and 14CO2 radioactivity were determined when fat body was submitted to gradual hypoxia. The modifications in the specific radioactivity kinetics and in the cumulative yields of total 14CO2 derived from [1-14C]glucose and [6-14C]glucose molecules under gradual hypoxia, were measured. Catabolic corpora cardiaca hormonal extracts from Tenebrio strongly inhibited the utilization of the pentose cycle in the in vitro degradation of fat body glucose, when the respiratory gaseous mixture contained 30% O2. This effect was drastically reduced when fat body underwent hypoxia (5% O2). 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 the respiratory gaseous mixture contained 30% O2; this dose-dependent effect was increased when fat body underwent hypoxia (5% O2).