ADENYLATE COMPARTMENTATION AND STORAGE IN CELOMIC CELLS OF THE POLYCHAETE NEREIS-VIRENS

The concentrations of adenine nucleotides (AMP, ADP, ATP) were determi ned in coelomic cells (eleocytes) of the polychaete Nereis virens. In cells of immature and male animals, total ADP and AMP contents (each 1 0-15 mu mol ml(-1) packed cell volume) greatly exceeded that of ATP (0 .8 mu mol ml(-1) packed cell volume). P-31-nuclear magnetic resonance (NMR) studies of living eleocytes showed that the high concentrations of both AMP and ADP are free in solution. Comparisons of in vivo NMR s pectra with those obtained from metabolite extracts of eleocytes sugge st that the adenylate pools are compartmentalized, with a large pool b eing in an environment with a pH<6.0 and a small pool being in a domai n where pH>6.7. This indicates that eleocytes are capable of storing h igh concentrations of ADP and AMP without inhibiting energy metabolism by sequestering these compounds into an acidic compartment. The large acidic vacuole characteristic of eleocytes may function as this compa rtment.