BACKGROUND The enteric nervous system is important in the pathophysiology of intestinal fluid secretion induced by cholera toxin (CT),Escherichia coli heat labile (LT), and heat stable (STa) toxins. The neurotransmitters involved are not fully elucidated. Vasoactive intestinal polypeptide (VIP), a potent intestinal secretagogue present in the enteric nervous system, is increased after exposure of the cat intestine to CT. Whether VIP is involved in the pathogenesis of cholera and other toxins in not known.

AIM To study in vivo the effect of VIP antagonism on jejunal fluid secretion induced by CT, LT, and STa.

RESULTS VIPa had no effect on basal intestinal fluid absorption. CT induced net fluid secretion (median −68 μl/min/g dry intestinal weight (interquartile range −80 to −56)) which was dose dependently reversed by VIPa (6.2 (−16 to 34) and 29 (17 to 42); p<0.01). Similarly, LT induced secretion (−63 (−73 to −30)) was attenuated by VIPa (0.2 μg/kg/min) (−15 (−24 to −1); p<0.01) and totally reversed to normal levels by VIPa (2 μg/kg/min) (37 (28–56); p<0.01 compared with LT and not significant compared with normal controls). STa induced secretion (−17 (−19 to −2)) was also reversed by VIPa (12 (9–23) and 14 (0–26); p<0.01).

CONCLUSION VIP plays an important role in CT, LT, and STa induced intestinal secretion and may be the final putative neurotransmitter in the pathophysiology of these toxins.