Transport kinetics by both everted and non-everted unfed tissues measured with magnesium ionophore VI.

A) Esophageal and B) Rectal magnesium fluxes in the serosal fluid for non-everted (N = 4) and the mucosal fluid for everted (N = 4) tissue of unfed C. auratus. Cortland saline containing 0–64 mM MgSO4 was applied to the mucosal surface of the esophagus. Cortland saline containing 0–32 mM MgSO4 was applied to the mucosal surface of the rectum. Positive values in non-everted preparations indicate appearance in the serosal fluid (suggesting mucosal-to-serosal movement) and negative values in everted preparations indicate disappearance from the mucosal fluid (suggesting mucosal-to-serosal movement). Data represent mean flux ± S.E.M. Regression analysis revealed a significant (p2+ concentration and Mg2+ transport rate in the esophagus and a significant (p 2+ concentration and Mg2+ transport rate fitting a Michaelis-Menten curve with single saturation in the rectum. See text for more details.