IMPORTANCE OF KETONE-BODIES TO THE INTERMEDIARY METABOLISM OF THE TERRESTRIAL SNAIL, ARCHACHATINA-VENTRICOSA - EVIDENCE FROM ENZYME-ACTIVITIES

The maximal activities of enzymes of ketone body metabolism and select ed enzymes of other pathways of intermediary metabolism were measured in heart, hepatopancreas, kidney, mantle and foot muscle of the terres trial pulmonate gastropod Archachatina ventricosa. These measurements indicate the importance of ketone bodies in the energy metabolism of s everal aerobic tissues in this snail. Three enzymes that catalyze step s in the pathway to convert ketone bodies to acetyl-CoA are particular ly high in the ventricle, which suggests that beta-hydroxybutyrate and acetoacetate are important energy substrates in this tissue. The orga nization of ketone body metabolism in A. ventricosa tissues appears to differ from that of mammals in that no hydroxymethylglutaryl-Coh synt hase activity is detected in any tissue. However, ketogenesis may occu r through other pathways, including the readily reversible reactions o f the ketolytic pathway. Our data suggest that the kidney may be a ket ogenic tissue in these snails. (C) 1997 Elsevier Science Inc.