ACCELERATING EFFECT OF SEROSAL HCO3- ON NA+ TRANSPORT IN SHORT-CIRCUITED TURTLE BLADDERS

The isohydric addition of HCO3- to the serosal fluid (final concn., 17 mM) of short-circuited turtle bladders produces a sustained increase (near-doubling) in the rate of Na+ transport from mucosa to serosa. A qualitatively similar, but smaller, effect was obtained from addition of Cl- to the serosal fluid. The anion-induced acceleration of Na+ transport was independent of the presence or absence of HCO3- and/or Cl- in the mucosal fluid. Whereas the transport-accelerating effect of HCO3- could be superimposed upon that of Cl-, the reverse did not hold. The presence and utilization of glucose is apparently an absolute requirement for eliciting the HCO3- effect on Na+ transport. On the other hand, the effect was elicited in anoxic as well as in oxygenated bladders. The O2-induced recovery of Na+ transport from N2-anoxia is dependent upon the presence of serosal HCO3-. © 1969.