Oxalate Transport in Rat Renal-Cortical Brush-Border-Membrane Vesicles

Abstract

From clearance studies using rats, oxalate has been found to be freely filtered at the glomerulus and to undergo net secretion in the proximal tubule (1), Micropuncture studies have suggested the possibility that more than one oxalate transport system exists in rat proximal tubules (2). In this study, we found the presence of an oxalate transport system on the brush border membrane of proximal tubular cells. Generally, the presence of a specific transport system is inferred when the following criteria for a transport process are satisfied: a) existence of a specific inhibitor that blocks mediated transport; b) specificity of a transport system for oxalate; c) temperature-dependency of oxalate uptake; d) saturability with respect to substrate; and e) transport by an electro-neutral process (3). We investigated the characteristics of oxalate transport based on these criteria.