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Abstract

A growing body of evidence implicates albumin has an important regulatory function in renal proximal tubule cells (PTCs). In present study, the effect of bovine serum albumin (BSA) on 14C-α-methyl-d-glucopyranoside (α-MG) uptake and its related signal molecules were examined in the primary cultured rabbit renal PTCs. BSA significantly increased uptake of α-MG, a distinctive proximal tubule marker, as well as expression level of Na+/glucose cotransporters (SGLT1 and SGLT2) proteins. The BSA-induced increase of α-MG uptake was completely blocked by actinomycin D and cycloheximide. Neomycin or U 73122 (PLC inhibitors), BAPTA/AM or TMB-8 (intracellular Ca2+ mobilization inhibitors) completely abolished BSA-induced increase of α-MG uptake. BSA significantly increased IPs accumulation, but did not affect Ca2+ uptake. Effect of BSA on α-MG uptake was blocked by PD 98059, but did not SB 203580. BSA increased phosphorylation of p44/42 mitogen activated protein kinase (MAPK) in a time-dependent manner. NAC or catalase (antioxidants) significantly blocked BSA-induced increase of H2O2 formation and α-MG uptake. BSA activated NF-κB translocation into nucleus. PDTC, SN50, and TLCK (NF-κB inhibitors) also completely blocked BSA-induced increase of α-MG uptake, NF-κB p65 and phospho IκB-α activation. In conclusion, BSA stimulates α-MG uptake and its action is partially correlated with PLC, MAPK, or NF-κB signal molecules in primary cultured renal PTCs. © 2005 Wiley-Liss, Inc.