Maintenance of glucose uptake in suspensions and cultures of human renal proximal tubular cells

Abstract

Many nephrotoxic agents exert their toxic effects in a well-defined region of the kidney. For example, the toxicity of cephaloridine and the aminoglycosides is confined to proximal tubular (PT) cells [I], whereas prolonged uptake of paracetamol results in papillary necrosis [Z]. This site-specific toxicity is due to the ability of the cells to concentrate a nephrotoxin, through various transport processes, or their capacity to metabolise a compound to a more toxic intermediate. PT cells are an important site for drug and xenobiotic damage for a number of reasons: (a) they are the first metabolically/functionally important cells to receive the glomerular filtrate and efferent renal blood supply; (b) they are known to transport many organic and inorganic compounds by active processes; and (c) they exhibit a wide range of drug-metabolising reactions, including cytochrome P-450, j?-lyase and y-glutamyltransferase (y-GT) activty. If the site-specific mechanisms of PT cell damage are to be investigated, then the development of a well-defined in vitro model is essential. In this context the use of a homogeneous cell population in suspension and in particular the growth of cells in primary culture would prove powerful investigative tools, provided that they retain the renal specific functions found in vivo. The aim of this study was to determine whether PT cells could be isolated with high viability from human kidney cortex, and be subsequently characterised in suspension and primary culture in terms of the Na+-dependent uptake of glucose, which is a functional characteristic of PT cells. The ultimate aim is to characterise the human PT cells in suspension and primary culture and subsequently to use these in vitro models to investigate the biochemical mechanisms of drug-induced PT cell toxicity.