Calcium-dependent diuretic system in preascitic liver cirrhosis

Background & Aims Extracellular Ca++ activates cell membrane calcium-sensing receptors (CaRs), leading to renal tubule production of prostaglandins E2 (PGE2 ), which decrease both sodium reabsorption in the thick ascending limb of Henle’s loop and free-water reabsorption in collecting ducts. Aims & Methods To assess the activity of this diuretic system in experimental cirrhosis, we evaluated renal function, hormonal status, PGE2 urinary excretion, and renal tissue concentrations of Na+ –K+ –2Cl− co-transporters (BSC-1) and CaRs in three groups of rats: one group of controls receiving 5% glucose solution (vehicle) intravenously and two groups of rats with CCl4 -induced preascitic cirrhosis receiving either vehicle or 0.5 mg i.v. Poly- l -Arginine (PolyAg), a CaR-selective agonist. Results Compared to controls, cirrhotic rats showed reduced urine volume and sodium excretion ( p