American Journal of Physiology: Gastrointestinal & Liver Physiology. Apr2003, Vol. 284 Issue 4, pG670. 13p. 4 Black and White Photographs, 4 Charts, 26 Graphs.
American Journal of Physiology: Regulatory, Integrative & Comparative Physiology. Feb2003, Vol. 53 Issue 2, pR363. 9p. 3 Black and White Photographs, 2 Charts, 13 Graphs.