Energy Metabolism During Anoxia and Recovery in Shell Adductor and Foot Muscle of the Gastropod MolluscHaliotis lamellosa:Formation of the Novel Anaerobic End Product Tauropine

Abstract

Metabolic responses to experimental anoxia and subsequent recovery, and to exercise were investigated in two different muscular tissues of the ormer, Haliotis lamellosa. The tissues are employed for different tasks by the animal. The foot is mainly responsible for slow gliding movements. The shell adductor muscle pulls down the shell for protection and in righting an animal which has been dislodged from the rocks. Tissue-specific differences in anaerobic energy metabolism occur. During 6 h of experimental anoxia, energy for both muscles was provided by arginine phosphate and co-fermentation of glycogen and aspartate. Glycolysis in the shell adductor muscle led mainly to the formation of the novel end product tauropine; D-lactate production pre-dominated in the foot. This pattern is consistent with observed enzymatic profiles in the two muscles and with the equilibrium constants of the respective enzymes, tauropine and D-lactate dehydrogenase. Recovery from anaerobiosis was characterized by a rapid return of the phosphagen pool and the energy charge to the aerobic state. A protracted time-course was observed for the clearance of glycolytic end products.Exercise, primarily powered by the shell adductor muscle, was mainly fueled by glycolysis resulting mostly in the accumulation of tauropine.