Forte LR, Fan X, Hamra FK, Eber SL, Krause WJ, Lim RW, Pace VM, Currie MG, Freeman RH
Uroguanylin: Circulating natriuretic peptide from the intestinal mucosa and heart
16th Scientific Meeting of the International Society of Hypertension
ISH Abstract Book (Jun) 16: 1996

An intestinal factor responsible for the natriuresis elicited by oral salt has long been sought. A candidate peptide named uroguanylin that activates membrane guanylate cyclases found in the intestine and kidney was initially isolated from opossum urine and subsequently purified from intestinal mucosa. This interesting study reports the isolation by molecular cloning of cDNAs encoding the 109 amino acid preprouroguanylin from an opossum colon cDNA library. Bioactive uroguanylin is located at the C-terminus of this precursor polypeptide.

Preprouroguanylin mRNAs of 1.2 kb were detected throughout the small and large intestine and surprisingly, in the atria and ventricles of heart. Transcripts were not found in kidney, stomach or liver. Preproguanylin mRNAs of 0.8 kb were only detected in the intestine. Uroguanylin and prouroguanylin were also isolated from opossum plasma by preparative isoelectric focusing and reverse phase HPLC. Activation of renal uroguanylin receptors in vivo stimulated the urinary excretion of sodium, potassium and cGMP.

Comment: Uroguanylin is made by the intestine and heart and circulates in the bloodstream linking the intestine and heart with the kidney to regulate urinary salt excretion. Uroguanylin may be released from the intestinal mucosa upon salt ingestion, thus regulating salt and water homeostasis by balancing urinary NaCl excretion to match salt intake. (Carmine Zoccali, M.D, Reggio Calabria, Italy).

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16th Scientific Meeting of the International Society of Hypertension
H: Pathophysiology : Salt (sodium, chloride) sensitivity
H: Special problems : Endocrine hypertension