Calcium transport across avian uterus. I. Effects of electrolyte substitution.

PEARSON, TERRY W., AND ANDREW M. GOLDNER. Calcium transport across avian uterus. I. E$Ects of electro&e substitution. Am. J. Physiol. 225(6) : 1508-l 5 12. 1973.-Unidirectional calcium fluxes from serosa to mucosa (JS,, ) and mucosa to serosa (Jmds ) were determined across the isolated quail uterus. When the tissue was bathed with normal bicarbonate buffer, the spontaneous electrical potential difierence was approximately 8 mv, mucosal surface negative. Tissue conductance was 27 mmho cm-2. The short-circuit current could not be explained by the net flux of sodium ion, calcium ion, or the sum of these fluxes. When the electrochemical gradient across the tissue was maintained at zero, there was a net flux of 0.164 PEq cm-2hr-1 in the secretory direction, serosa to mucosa. Removal of sodium ion did not alter net calcium flux; however, individual removal of the anions reduced the net flux primarily by reducing the serosa to mucosa flux. Bicarbonate removal reduced net calcium flux to 0.069 PEq cm-2hr? These results indicate that calcium transport across the avian uterus can occur against an electrochemical gradient and that the net flux is dependent in part on bicarbonate ion.