LONG-TERM ANAEROBIC METABOLISM OF ERYTHROCYTES OF THE ARCID CLAM SCAPHARCA INAEQUIVALVIS

Metabolic events up to 5 days in vivo anoxia incubation are described in the red blood cells of the blood clam Scapharca inaequivalvis, In t he first 3 h, respiration is sustained by endogenous oxygen stores. In the subsequent 9 h, the drop in aspartate equals the sum of increase in malate and succinate, and the utilization of aspartate also appears to be linked to the conversion of glucose into alanine. After 12 h an oxia there is no further utilization of aspartate, but alanine, malate and succinate continue to accumulate, whereas propionate accumulation in the whole tissue cells is initiated, This points to a gradual shif t away from pyruvate towards oxaloacetate in the phosphoenolpyruvate c onversion which seems to be completed after about 48 h. There is a gra dual increase of glucose during the first 4 days (hyperglycemia). The transmembrane gradient for glucose is near unity, Only shortly after t he accumulation of the volatile fatty acids propionate and acetate in the whole tissues has started, these compounds also appear in the incu bation water. This indicates a very easy transport of these compounds. In vitro incubations of red blood cells show, however, that anaerobic propionate accumulation is a feature which have these cells in common with other tissue cells. From day 2 onwards anaerobic metabolism has reached a steady state with propionate and acetate as the sole ferment ative products of glucose which are completely excreted.