title: Role of vasopressin in diabetes mellitus-induced changes in medullary transport proteins involved in urine concentration in Brattleboro rats.
abstract: In rats with streptozotocin-induced diabetes mellitus for 10-20 days, we showed that the abundance of the major medullary transport proteins involved in the urinary concentrating mechanism, urea transporter (UT-A1), aquaporin-2 (AQP2), and the Na+-K+-2Cl- cotransporter (NKCC2/BSC1), is increased, despite the ongoing osmotic diuresis. To test whether vasopressin is necessary for these diabetes mellitus-induced changes in UT-A1, AQP2, or NKCC2/BSC1, we studied Brattleboro rats because they lack vasopressin. Brattleboro rats were given vasopressin (2.4 microg/day via osmotic minipump) for 5 or 12 days. At 5 days, vasopressin increased AQP2 protein abundance but decreased UT-A1 abundance compared with untreated Brattleboro rats. At 12 days, vasopressin increased the abundance of both UT-A1 and AQP2 proteins but did not alter NKCC2/BSC1. Next, untreated Brattleboro rats were made diabetic for 10 days by injecting them with streptozotocin (40 mg/kg). Diabetes mellitus increased the abundance of AQP2 and NKCC2/BSC1 proteins, but UT-A1 protein abundance did not increase. Third, vasopressin-treated Brattleboro rats were made diabetic with streptozotocin for 10 days. In vasopressin-treated Brattleboro rats, diabetes mellitus increased UT-A1, AQP2, and NKCC2/BSC1 protein abundances. Vasopressin significantly increased UT-A1 phosphorylation in vasopressin-treated diabetic Brattleboro rats but not in the other groups of Brattleboro rats. We conclude that 1) administering vasopressin to Brattleboro rats for 12 days, but not for 5 days, increases UT-A1 protein abundance and 2) vasopressin is necessary for the increase in UT-A1 protein in diabetic rats but is not necessary for the increase in AQP2 or NKCC2 proteins.
authors.affiliation: Emory Univ. School of Medicine, Renal Division, WMRB Rm. 338, 1639 Pierce Drive NE, Atlanta, GA 30322, USA.
authors.forename: Dongun
authors.initials: D
authors.lastname: Kim
authors.forename: Jeff M
authors.initials: JM
authors.lastname: Sands
authors.forename: Janet D
authors.initials: JD
authors.lastname: Klein
mesh_terms: D000818:Animals; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D005260:Female; D007671:Kidney Concentrating Ability / Q000187:drug effects* / Q000502:physiology*; D007679:Kidney Medulla / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D011910:Rats, Brattleboro; D017207:Rats, Sprague-Dawley; D012076:Renal Agents / Q000494:pharmacology*; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D064466:Solute Carrier Family 12, Member 1; D014667:Vasopressins / Q000494:pharmacology*; D000096982:Urea Transporters
chemical_list: D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D026901:Membrane Transport Proteins; D012076:Renal Agents; D028021:Sodium-Potassium-Chloride Symporters; D064466:Solute Carrier Family 12, Member 1; D014667:Vasopressins; D000096982:Urea Transporters; C496025:Aqp2 protein, rat; C578716:Slc12a1 protein, rat