Stimulation of Cl permeability in colonic crypts of Lieberkühn measured with a fluorescent indicator

Crypts of Lieberkühn were isolated from rabbit distal colon and the halide-sensitive dye 6-methoxy-N-[3-sulfopropyl]quinolinium was used to monitor changes in cell Cl by fluorescence microscopy. Distal colon from rabbits actively secretes Cl and K when stimulated with prostaglandin (PG) E2 but secretes only K in response to epinephrine. The secretagogues PGE2 and epinephrine each produced transient decreases of the apparent cell Cl concentration in about one-half of the crypt cells. Permeability to Cl was assessed by brief substitutions with gluconate or Br in the bath. After stimulation of secretion by PGE2 or epinephrine, Cl efflux and Br influx were increased but only in the cells that exhibited the decrease in cell Cl at the onset of stimulation. Although Cl efflux during gluconate substitution was stimulated similarly with either PGE2 or epinephrine, epinephrine stimulation led to a lower apparent Cl concentration after 2 min of gluconate substitution. Together these results support the concept that a particular epithelial cell type in the crypts responds to secretagogues and that the Cl permeability pathways differ between the secretory states induced by PGE2 and epinephrine.