[Value of protecting mitochondrial functions during treatment with cyclosporin A]

The use of cyclosporin A is often limited by its nephrotoxicity. This dose-dependent toxicity can occur in all kinds of transplantation and is reversed with drug withdrawal. Cyclosporin A induces a vasoconstriction leading to an increase of renal vascular resistance and a reduction of glomerular filtration. Histochemical studies show mitochondrial alterations and an excess of cytosolic and mitochondrial calcium leading to a decrease of ATP synthesis. Two strategies can be evoked for limiting cyclosporin-A-induced nephrotoxicity. First, the use of drugs counteracting the vasoconstriction has been proposed. Second, drugs acting by restoration of ATP synthesis could also be of interest. For example, calcium channel blockers may be used for limiting the Ca2+ fluxes into cells. Another way to protect ATP synthesis is to inhibit the cyclosporin-A-induced increase of mitochondrial Ca2+ concentrations; Trimetazidine has shown its efficiency in vitro for protecting mitochondria against these modifications of Ca2+ homeostasis and is under clinical evaluation.