Glutathione Transport in the Kidneys: Experimental Models, Mechanisms, and Methods

Although investigators have often focused on the role of glutathione (GSH) in drug metabolism and protection from reactive oxygen species and toxic electrophiles, membrane transport processes also play a critical role in the overall homeostasis of GSH in the body. Although the liver is the primary source of extracellular GSH, the kidneys are relatively unique in possessing plasma membrane transport systems for both uptake and efflux of GSH and are the major sites for clearance of circulating GSH from the plasma. This chapter reviews the various aspects of how GSH is transported across the plasma and mitochondrial inner membranes in renal cells, with a focus on the appropriate choice of experimental model and considerations important in accurately quantifying transport. Model systems for measuring plasma membrane transport of GSH that are discussed include isolated cells and tubules and membrane vesicles. Model systems for measuring mitochondrial transport of GSH include isolated cells coupled with digitonin fractionation, isolated mitochondria and mitoplasts, purified and reconstituted carrier proteins, and bacterially expressed, purified and reconstituted recombinant carrier proteins. GSH is truly a “molecule on the move” and accomplishes this by highly regulated, carrier-mediated processes that can be exploited to modulate and characterize cellular and mitochondrial redox homeostasis.