Effect of arachidonic acid on Na+/H+ exchange and neutral amino acid transport in sea urchin eggs.

We have investigated the role of arachidonic acid (AA) in regulation of sea urchin egg metabolism activated after fertilization. We show in this paper that addition of exogenous AA to fertilized eggs triggered a transitory stimulation of three ionic events related to the Na+/H+ exchange, H+ excretion, and increase in Nai and in pHi. AA also induced a complete inhibition of neutral amino acid uptake. We found that alterations in this Na(+)-dependent amino acid uptake induced by AA came from modifications in the intracellular sodium concentration. We discuss how AA or derivates may play a role in regulating intracellular free calcium concentration and pH.