22Na+ and 86Rb+ fluxes in spermatozoa and oocytes of arbacia punctulata

The fluxes of 22Na+ and 86Rb+ in Arbacia sperm and oocytes were studied in order to determine how these cells carry out cation exchange with the sea environment. The uptake of these ions by serum followed a pattern of early rapid influx (initial 0.5 min) and subsequent efflux (1–3 min) followed by a gradual uptake (after 3 min). Neither the uptake nor the efflux of these cations by Arbacia sperm were affected by ouabain, suggesting that influx and efflux of 22Na+ and 86Rb+ in Arbacia sperm occur predominantly by passive transport. The 22Na+ uptake by Arbacia oocytes showed a steady increase after an initial rapid uptake. A slight but significant inhibition of 22Na+ uptake was observed with ouabain. However, 86Rb+ uptake by the oocytes reached an early equilibrium and was not affected by ouabain. The uptake of Rb+ by Arbacia oocyte is by passive transport while that of Na+ is both by passive and active transport.