Low aquaporin-2 excretion in the nephrotic syndrome: an escape from the vasopressin regulating effect

Mikhail Brovko,1 Lidia Kozlovskaya,1 Andrey Pulin,1,2 Sergey Moiseev,1 Victoria Sholomova,1 Dmitry Shchekochikhin,1 Daria Gognieva,1 Ludmila Milovanova,1 Victor Fomin1 1Sechenov First Moscow State Medical University, Moscow, Russia; 2Laboratory for Cell Technologies and Developmental Pathology, Federal State Budgetary Scientific Institution “Institute of General Pathology and Pathophysiology,” Moscow, Russia Purpose: Experimental studies suggest that the nephrotic syndrome is associated with “vasopressin escape”, characterized by low aquaporin-2 (AQP2) expression in the collecting duct despite high vasopressin secretion. We investigated this phenomenon in patients with the nephrotic syndrome. Patients and methods: We recruited 47 patients with proteinuric kidney disease who were distributed into the following four groups: 1) nephrotic syndrome with kidney dysfunction (n=10); 2) nephrotic syndrome with normal kidney function (n=16); 3) partial remission of nephrotic syndrome (n=10); and 4) minimal proteinuria (n=11). Nine healthy volunteers comprised a control group. Serum copeptin level (as a marker of vasopressin secretion) and urinary AQP2 were measured using ELISA. Results: Nephrotic syndrome was associated with a significant increase in serum copeptin levels compared with those in the other groups (all P