Studies on the avian shell gland during egg formation: the effect of acetazolamide on the transfer of ions to the albumen.

Twenty-five laying hens were fed on a diet containing 100 mg acetazolamide/kg in order to determine the effects of a decrease in the activity of carbonic anhydrase on the transfer of minerals to the egg albumen. Treatment with acetazolamide decreased the rate of shell formation by 44%; reduced the concentrations of water and Na+ in the albumen at the beginning of the plumping stage but increased the accumulation of water during plumping; increased the concentration of Cl- in the albumen after the 6-h stage without any appreciable change in K+ and Ca2+ concentrations. The computed relationships between the concentrations of different ions also showed that the transfer of water and Na+ were linked during egg formation, that a water-independent, acetazolamide-sensitive reabsorption of Na+ occurred after the 10-h stage and that Na+ and Cl- moved simultaneously up to 14 h but with the ratio of Cl- to Na+ three times higher in the treated group. It is concluded that acetazolamide impairs the transfer of Na+ and Cl- between the albumen and the extracellular fluid and that secretion of Ca2+ into the uterine lumen seems to depend on Na+ and Cl- reabsorption.