AJP - Cell Physiology, Vol 262, Issue 6 C1392-C1402, Copyright © 1992 by American Physiological Society
Secretion of K and Cl across colonic epithelium: cellular localization using electron microprobe analysis
D. R. Halm and R. Rick
Department of Physiology, Ohio State University, Columbus 43210.
Electron microprobe analysis of quick-frozen distal colonic epithelium from
guinea pig was used to locate the cells responding to secretory stimuli.
Concentrations of Na, K, and Cl were similar for cells of surface and crypt
in the unstimulated state, 8, 149, and 46 mmol/kg wet weight, respectively.
Stimulation of either K and Cl secretion with prostaglandin E2 or K
secretion alone with epinephrine increased Na to approximately 12 mmol/kg
wet weight in crypt cells but not in surface cells or cells in the crypt
neck. This result supports the location of ion secretory cells in the lower
two-thirds of the crypt. In the vacuoles of crypt columnar cells,
stimulation of KCl secretion decreased K, S, Mg, and Ca and increased Na
and Cl, indicative of the concomitant release of vacuole contents. Mucin
granules in crypt goblet cells contained more S and Mg than granules in
surface goblet cells. These findings support the concept of differentiation
in ion and macromolecular secretory function along the axis from crypt to
surface epithelium.
