Effects of scorpion venom on electrolyte transport by rabbit ileum

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Abstract
Scorpion venom, which depolarizes nerves, was used to obtain further evidence that intramural nerves affect ion transport by the rabbit ileum. Ileal epithelium, stripped of muscularis propria, was mounted in a flux chamber modified to permit electrical field stimulation (EFS) of the tissue. Response of the short-circuit current (Isc) to venom was most rapid on the serosal surface, and the response was eliminated by tetrodotoxin. Isc response was influenced by venom batch number and by factors within the tissue. Venom (10 .mu.g/ml) and EFS each caused chloride secretion by reducing mucosal-to-serosal movement and by increasing serosal-to-mucosal movement. Na transport and residual ion fluxes did not change. In the presence of venom, EFS caused no further changes in ion transport, but tissues still responded to glucose and to aminophylline. The early peak of Isc was reduced .apprx. 40% by atropine, implying that acetylcholine, released by venom, stimulated muscarinic receptors. The blockade of the Isc response to venom with tetrodotoxin was further evidence that venom depolarized intramural nerves and liberated transmitters that caused chloride secretion. The identity of the other transmitters was not known.