Small bowel review: normal physiology part 2.

In the past year there have been many advances in the area of small bowel physiology and pathology and therapy. In preparation for this review, over 1500 papers were assessed. The focus is on presenting clinically useful information for the practising gastroenterologist. Selected important clinical learning points include the following: (1) numerous peptides are being identified which stimulate the proliferation and functional response of the small intestine to disease or resection, and may in time find a clinical use; (2) under usual in vivo conditions, absorption of nutrients has little effect on the paracellular movement of water; (3) the permeability of the intestine is modified by the function of the tight junctions, and measuring intestinal permeability may be useful to reflect the presence of disease; (4) the release of serotonin is influenced by cholinergic, adrenergic, and nonadrenergic, noncholinergic mechanisms, and serotonin agonists and antagonists may play an important future role in the treatment of motility disorders; (5) the use of endothelin receptor antagonists may be useful for the treatment of intestinal anaphylaxis; (6) the alterations in intestinal pH and motility in patients with Crohn's disease may influence the action of pH- or time-dependent release medications; and (7) patients with irritable bowel syndrome may also have abnormalities in gastric and small intestinal motility.