title: Solute-free water retention in preascitic cirrhotic rats following intravenous water loading.
abstract: Increased extracellular fluid volume (ECF) characterizes compensated cirrhosis. To identify the mechanisms of fluid retention in cirrhosis through clearance methods, 10 control and 10 preascitic rats with CCl(4)-induced cirrhosis were studied following i.v. loading with 1 ml 5% glucose solution. Glomerular filtration rate and renal plasma flow were evaluated through inulin and para-aminohippurate clearances; water and electrolyte handling was assessed measuring urine and plasma osmolarity, electrolyte excretions, and tubular solute-free water reabsorption (TFWR = osmolar clearance minus urinary output); ECF was assessed through hormonal status determination. After water loading, cirrhotic rats had increased ECF (lower plasma renin activity and aldosterone and higher atrial natriuretic peptide levels, all P<0.03), solute-free water retention (increased TFWR and decreased plasma osmolarity, all P<0.05), reduced absolute and fractional sodium excretions (P<0.05). Cirrhotic rats showed sodium retention in the medullary thick ascending limb of Henle's loop (i.e. increased values of TFWR for any given value of osmolar clearance). Trans-tubular potassium gradient in medullary collecting duct was similar in the two groups (P=0.55), ruling out aldosterone-dependent sodium retention and potassium hyper-secretion. In experimental preascitic cirrhosis NaCl retention in the ascending limb of Henle's loop increases medullary interstitial tonicity leading to vasopressin-independent water back-diffusion in thin descending limb of Henle's loop and collecting duct.
authors.affiliation: Gastroenterology Unit, Gradenigo Hospital, Turin, Italy. giovannisan@iol.it
authors.forename: G
authors.initials: G
authors.lastname: Sansoe
authors.forename: M
authors.initials: M
authors.lastname: Aragno
authors.forename: A
authors.initials: A
authors.lastname: Smedile
authors.forename: M
authors.initials: M
authors.lastname: Rizzetto
authors.forename: F
authors.initials: F
authors.lastname: Rosina
mesh_terms: D000450:Aldosterone / Q000097:blood; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood; D045604:Extracellular Fluid / Q000502:physiology; D005919:Glomerular Filtration Rate; D007668:Kidney / Q000098:blood supply; D007686:Kidney Tubules, Distal / Q000378:metabolism; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000503:physiopathology*; D008138:Loop of Henle / Q000503:physiopathology*; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000097:blood / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000097:blood; D012964:Sodium / Q000008:administration & dosage / Q000097:blood / Q000652:urine; D014667:Vasopressins / Q000097:blood; D014867:Water / Q000008:administration & dosage; D014883:Water-Electrolyte Imbalance / Q000503:physiopathology*
chemical_list: D014867:Water; D014667:Vasopressins; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012964:Sodium; D012083:Renin; D011188:Potassium