Modification of sodium transport in freshwater mussels by prostaglandins, cyclic AMP and 5-hydroxytryptamine: effects of inhibitors of prostaglandin synthesis.

Pondwater acclimated unionid mussels, Ligumia subrostrata, experienced an increased Na influx, compared to controls, when injected with the phospholipase A2 inhibitor dexamethasone, or the cyclooxygenase inhibitors N-(2,6-dichloro-m-tolyl) anthranilic acid (meclofenamate) and indomethacin. Prostaglandin E2 (PGE2) or PGF2 alpha injections inhibited Na transport by depressing Na influx with no change in Na efflux. Prostaglandin E2 injections inhibited the indomethacin and dexamethasone dependent increase in Na transport. The PGE2 inhibition of Na influx was reversed by the administration of dibutyryl cAMP. Injections of serotonin (5-HT) elevated Na influx in mussels and the stimulation of Na transport by 5-HT could be potentiated by the injection of meclofenamate.