Human colonic epithelial cells express galanin-1 receptors, which when activated cause Cl− secretion

Galanin is a peptide hormone widely expressed in the central nervous system and gastrointestinal (GI) tract. Within the GI tract galanin is present in enteric nerve terminals where it is known to modulate intestinal motility by altering smooth muscle contraction. Recent studies also show that galanin can alter intestinal short-circuit current (I sc) but with differing results observed in rats, rabbits, guinea pigs, and pigs. In contrast, nothing is known about the ability of galanin to alter ion transport in human intestinal epithelial tissues. By RT-PCR, we determined that these tissues express only the galanin-1 receptor (Gal1-R) subtype. To evaluate Gal1-R pharmacology and physiology, we studied T84 cells. Gal1-R expressed by these cells bound galanin rapidly (half time 1–2 min) and with high affinity (inhibitor constant 0.7 ± 0.2 nM). T84 cells were then studied in a modified Ussing chamber and alterations inI sc, a measure of all ion movement across the tissue, were determined. Maximal increases in I...