Date of Award


Document Type


Degree Name

Master of Science




The effects of increasing hydrogen ion concentration on rate of chloride influx and efflux were studied in the killifish, Fundulus heteroclitus, adapted to fresh water. Because increasing hydrogen ion concentrations have been shown to inhibit sodium influx and because evidence exists to support coupling of chloride transport with sodium transport, the present study was undertaken to determine what effect pH would have on rate of chloride flux. Chloride efflux rates were studied after the addition of sodium bicarbonate to the medium. No significant pH-dependent changes in efflux rate were observed, except at very low pH. Influx rates were significantly changed, especially at very low pH. Efflux rates with bicarbonate added tended to be lower than without bicarbonate. Flux ratios were high, net flux being outward. The possibility of a pH-sensitive chloride/bicarbonate exchange, as well as a hydrogen/sodium-coupled chloride transport system is proposed.

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