1. Whittle B.J.R. (1994) in The Physiology of the Gastrointestinal Tract. (Johnson, L.R. ed.) 3rd edn, Raven Press, New York.
2. Brown, J.F., Tepperman, B.L., Hanson, P.J., Whittle, B.J.R. and Moncada, S. (1992) Biochem. Biophys. Res. Commun. 184, 680–685.
3. Allen, A., Flemstrom, G., Garner, A. and Kivilaakso, E. (1993) Physiol. Rev. 73, 823–857.
4. Brown, J.F., Keates, A.C., Hanson, P.J. and Whittle, B.J.R. (1993) Am. J. Physiol. 265, G418–G422.
5. Knowles, R.G. and Moncada, S. (1994) Biochem. J. 298, 249–258.