title: Countercurrent system.
abstract: Urinary concentration is achieved by countercurrent multiplication in the inner medulla. The single effect in the outer medulla is active NaCl absorption from the thick ascending limb. While the single effect in the inner medulla is not definitively established, the majority of experimental data favors passive NaCl absorption from the thin ascending limb. Continued experimental studies in inner medullary nephron segments will be needed to elucidate fully the process of urinary concentration.
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: J M
authors.initials: JM
authors.lastname: Sands
authors.forename: J P
authors.initials: JP
authors.lastname: Kokko
mesh_terms: D000818:Animals; D003377:Countercurrent Distribution; D006801:Humans; D007671:Kidney Concentrating Ability / Q000502:physiology*; D007684:Kidney Tubules / Q000502:physiology*; D008954:Models, Biological; D012965:Sodium Chloride / Q000493:pharmacokinetics; D014508:Urea / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D012965:Sodium Chloride; D014508:Urea