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RESEARCH PRODUCT

Involvement of Peroxynitrite on the Early Loss of P450 in Short-Term Hepatocyte Cultures

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description

The biological chemistry of nitric oxide (NO) in the oxygenated cellular environment is extremely complex. It involves the direct interaction of NO with specific biomolecules and the so-called indirect effects, due to secondary more potent oxidant species derived from NO which are also able to react with DNA, lipids, thiols and transition metals (Wink et al. 1996; Nathan, 1992). In addition to its regulatory role as a signalling molecule (Nathan, 1992; Moncada and Palmer, 1991) it has become evident that NO (or NO-derived species) is a critical factor involved in various toxicological mechanisms (Wink et al. 1996; Wang et al. 1998; Estevez et al. 1999; Wink et al. 1999). Some controversy exists however about the damaging vs protective actions of NO on oxidative injury, whose biological significance in living cells and tissues remains still ill defined. Research in this laboratory (Lopez-Garcia, 1998; Lopez-Garcia and Sanz-Gonzalez, 2000) has shown that NO synthesis is significantly activated in hepatocytes from control rats following isolation by the classical collagenase-based procedure. NO overproduction appears to be due to the very early activation of liver constitutive Ca2+-dependent NO synthase (cNOS). Previous results have also provided first experimental evidence for the direct involvement of endogenously generated NO as a causal factor responsible for important phenotypic changes commonly observed in short-term cultured hepatocytes, which includes the early impairment of hepatocyte mitochondrial function -i.e., transient cell energy depletion-and glucose metabolism, and the well-known quick and irreversible loss of P450 content (Lopez et al 1987; Lopez-Garcia, 1998). This study aims to further characterise the mechanisms underlying this phenomenon.