[Guanylin family: new intestinal peptides regulating salt and water homeostasis]

Guanylin and uroguanylin are novel peptides that are first isolated from rat jejunum and opossum urine, respectively. They bind to and activate guanylyl cyclase-C (GC-C) to regulate intestinal and renal fluid and electrolyte transport through the second messenger, cyclic GMP. Heat-stable enterotoxins produced by pathogenic bacteria have close structural similarities to guanylin and uroguanylin, and they use this mimicry to act on GC-C, causing life-threatening secretory diarrhea. Guanylin primarily is restricted to the intestine, whereas uroguanylin is present in the stomach kidney, lung and pancreas in addition to intestine. Guanylin and uroguanylin in the intestine are secreted into the lumen and blood in response to sodium chloride administration. These peptides will function in salt and water transport in the intestine and kidney by luminocrine and/or endocrine actions. Guanylin peptide family links the intestine with the kidney and could play the physiological roles in the control of water and electrolyte balance.