title: The effect of solution non-ideality on membrane transport in three-dimensional models of the renal concentrating mechanism.
abstract: Previous models of the renal concentrating mechanism employ ideal approximations of solution thermodynamics for membrane transport calculation. In three-dimensional models of the renal medulla, predicted urine concentrations reach levels where these idealized approximations begin to break down. In this paper we derive equations that govern membrane transport for non-dilute solutions and use these equations in a three-dimensional model of the concentrating mechanism. New numerical methods were employed that are more stable than those employed previously. Compared to ideal solution models, the urea non-ideality tends to increase predicted osmolarities, whereas NaCl non-ideality decreases predictions.
authors.affiliation: Department of Mechanical Engineering, University of Delaware, Newark 19716.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: A S
authors.initials: AS
authors.lastname: Wexler
authors.forename: D J
authors.initials: DJ
authors.lastname: Marsh
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003198:Computer Simulation; D006982:Hypertonic Solutions / Q000493:pharmacokinetics; D007038:Hypotonic Solutions / Q000493:pharmacokinetics; D007671:Kidney Concentrating Ability; D007685:Kidney Tubules, Collecting / Q000502:physiology; D008138:Loop of Henle / Q000502:physiology; D008954:Models, Biological; D009318:Natriuresis; D009994:Osmolar Concentration; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D012996:Solutions / Q000737:chemistry*
chemical_list: D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D012996:Solutions; D000254:Sodium-Potassium-Exchanging ATPase