Effect of GABA on the electrical potentials across the mouse small intestine

The effects of gamma-aminobutyric acid (GABA) on transmural potential difference (PD) and radioactive chloride fluxes (J) across the mouse small intestine were studied. It was found that GABA decreased the PD and increased the J in both mucosal-to-serosal and serosal-to-mucosal directions (JMS and JSM) only at a concentration of or higher than 50 mM. The PD was increased by the presence of 10 mM glucose or glycine in bathing solutions. The PD was also decreased by increasing the osmolarity of the bathing solutions with increasing concentration of GABA, mannitol, sucrose, or glucose. Our results suggested that the hyperosmotic effect causes the decrease of PD and the increase of J across the mouse small intestine by GABA.