An inhibitory protein of intestinal fluid secretion reverses neuronal GABA transport.

Intestinal challenge with cholera toxin induces the synthesis of a hormone-like protein which counteracts intestinal hypersecretion. This study shows that the protein also inhibits GABA transport across the plasma membrane of Deiters' cells in rabbits. The inhibitory action of the protein was dose dependent, and 10(3) times more potent than met 5-enkephalin, hitherto the most effective known inhibitor of GABA transport in vitro. The influence of the protein on the plasma membrane was reversible, and did not affect either postsynaptic binding or uptake of GABA.