Some aspects of chloride exchange with relation to acid-base regulation in Nectarus Maculosus

The effect of exposure to increased carbon dioxide tensions on chloride movement across the respiratory exchange surfaces in the urodele Necturus maculosus was studied. Neither chloride efflux nor chloride influx had been previously demonstrated in this amphibian. No significant change in the chloride concentration of the external medium was observed in twelve control animals submerged for twelve hours in tap water (21 ± 1.0°C) equilibrated with air. A significant increase in the chloride concentration of the external medium was recorded in twelve experimental animals submerged for twelve hours in tap water (21 ± 1.0°C) equilibrated with 10% carbon dioxide. Results from this study suggest that Necturus may release chloride to the external medium in exchange for bicarbonate; the bicarbonate being used to buffer the decrease in blood PH caused by an increased carbon dioxide tension.