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 ciao models (isolated rat glomeruli and cul tured mesangial cells). For this study, sublethal doses of the uranium(VI)- bicarbonate complex were determined by cytotoxicity experiments on confluen t 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 b een assessed. Our results showed a significant reduction of PSA for glomeru li (-9% after 40 minutes of exposure to uranium: [U] = 100 mu M) and for ra t mesangial cells (-14% after 40 minutes), while PSA values for control glo meruli 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 r enal target is not only the proximal tubule, but demonstrate, for the first time, that nonlethal uranium doses can induce direct vasoactive effects on glomerular structures and especially on mesangial cells. (C) 1999 Elsevier Science Ltd. All rights reserved.