Uranium-induced Vasoreactivity in Isolated Glomeruli and Cultured Rat Mesangial Cells.

The present study is aimed at investigating direct vasocontractive effects of uranium on two glomerular in vitro models (isolated rat glomeruli and cultured mesangial cells). For this study, sublethal doses of the uranium(VI)-bicarbonate complex were determined by cytotoxicity experiments on confluent cultured mesangial cells. Afterwards, using a morphoquantitative approach (computerized image analyser) the variations of planar surface areas (PSA) of glomeruli and mesangial cells exposed to uranium(VI)-bicarbonate have been assessed. Our results showed a significant reduction of PSA for glomeruli (-9% after 40 minutes of exposure to uranium: [U]=100 mum) and for rat mesangial cells (-14% after 40 minutes), while PSA values for control glomeruli and mesangial cells remain stable (ranging from 2.5 to 3.5% after 40 minutes of exposure to HBSS medium). These findings suggest that uranium renal target is not only the proximal tubule, but demonstrate, for the first time, that non- lethal uranium doses can induce direct vasoactive effects on glomerular structures and especially on mesangial cells.