Protein abundance of urea transporters and aquaporin 2 change differently in nephrotic pair-fed vs. non-pair-fed rats

作者：Matar Raed N Bou; Malik Bela; Wang Xiaonan H; Martin Christopher F; Eaton Douglas C; Sands Jeff M; Klein Janet D^*

来源：American Journal of Physiology - Renal Fluid and Electrolyte Physiology, 2012, 302(12): F1545-F1553.

DOI：10.1152/ajprenal.00686.2011

• UT-A3
• nephrosis
• focal segmental glomerulosclerosis
• doxorubicin
• adriamycin

Bou Matar RN, Malik B, Wang XH, Martin CF, Eaton DC, Sands JM, Klein JD. Protein abundance of urea transporters and aquaporin 2 change differently in nephrotic pair-fed vs. non-pair-fed rats. Am J Physiol Renal Physiol 302: F1545-F1553, 2012. First published March 28, 2012; doi: 10.1152/ajprenal.00686.2011.-Salt and water retention is a hallmark of nephrotic syndrome (NS). In this study, we test for changes in the abundance of urea transporters, aquaporin 2 (AQP2), Na-K-2Cl cotransporter 2 (NKCC2), and Na-Cl cotransporter (NCC), in non-pair-fed and pair-fed nephrotic animals. Doxorubicin-injected male Sprague-Dawley rats (n = 10) were followed in metabolism cages. Urinary excretion of protein, sodium, and urea was measured periodically. Kidney inner medulla (IM), outer medulla, and cortex tissue samples were dissected and analyzed for mRNA and protein abundances. At 3 wk, all doxorubicin-treated rats developed features of NS, with a ninefold increase in urine protein excretion (from 144 +/- 21 to 1,107 +/- 165 mg/day; P < 0.001) and reduced urinary sodium excretion (from 0.17 to 0.12 meq/day; P < 0.001). Urine osmolalities were reduced in the nephrotic animals (1,057 +/- 37, treatment vs. 1,754 +/- 131, control). Unlike animals fed ad libitum, UT-A1 protein abundance was unchanged in nephrotic pair-fed rats. Glycosylated AQP2 was reduced in the IM base of both nephrotic groups. Abundances of NKCC2 and NCC were consistently reduced (71 +/- 7 and 33 +/- 13%, respectively) in both nephrotic pair-fed animals and animals fed ad libitum. In pair-fed nephrotic rats, we observed an increase in the cleaved form of membrane-bound gamma-epithelial sodium channel (ENaC). However, alpha-and beta-ENaC sub-units were unaltered. NKCC2 and AQP2 mRNA levels were similar in treated vs. control rats. We conclude that dietary protein intake affects the response of medullary transport proteins to NS.

• 出版日期2012-6