RESUMO
The in vivo effect of cyclosporin A (CsA) on renal calcium oxalate (CaOx) crystal retention in experimental hyperoxaluric rats was investigated. Further, the effect of pretreatment of vitamin E on the above conditions was also studied. Male Wistar rats were divided into two major groups each containing 40 rats. One of the groups was pretreated with vitamin E. Both major groups were then subgrouped into four groups: group 1 received the vehicle (olive oil); group 2 received CsA in olive oil (50 mg/kg); group 3 received 3% ammonium oxalate (AmOx), and group 4 received CsA + AmOx. Nephrotoxicity was assessed by the activities of urinary marker enzymes and also by histopathology. Urinary oxalate excretion as well as the activities of lactate dehydrogenase, gamma-glutamyltranspeptidase, alkaline phosphatase and inorganic pyrophosphatase enzymes were elevated either in CsA-alone or AmOx-alone treated groups. On combined administration of both CsA and AmOx, further elevations of these enzymes were observed. Urinary excretion of oxalate concentration positively correlated with urinary excretion of these enzymes. Deposition of CaOx crystals was seen only in the kidneys of rats that received combined treatment. On pretreatment with vitamin E the observed increased urinary activities of the enzymes and oxalate, histopathological changes and the deposition of CaOx crystals by administration of CsA in hyperoxaluria were prevented suggesting that vitamin E could be supplemented to prevent CsA-induced membrane damage.