8-bromocyclic-gmp and Necrosis

Preconditioning of livers with the atrial natriuretic peptide (ANP) markedly reduces hepatic ischemia-reperfusion injury. Aim of this study was to characterize the influence of ANP preconditioning on necrotic and apoptotic cell death and on proliferation.. Rat livers were perfused with Krebs-Henseleit buffer with or without ANP or its second messenger analogue 8-Bromo cyclic guanosine monophosphate (8-Br cGMP) for 20 min, stored in cold University of Wisconsin solution (24 h), and reperfused for up to 120 min. Apoptosis and necrosis were determined using biochemical and morphological criteria, proliferation was assessed by Ki67 histochemistry.. Apoptosis peaked after 24 h of cold ischemia. Preconditioning with both ANP and 8-Br-cGMP significantly reduced caspase-3-like activity and the number of triphosphate nick-end labelling-positive cells. Reduction of apoptosis was significant for hepatocytes, but not for endothelial cells. After ischemia, degenerative cell changes were clearly reduced in ANP pretreated livers. After reperfusion, ANP preconditioning led to a significant reduction of necrotic hepatocytes and endothelial cells in periportal zones. Cell proliferation was not affected by preconditioning.. ANP reduces necrotic and apoptotic cell death without affecting the proliferation status. The protection takes place mainly in the periportal area and seems to be most prominent against necrosis of hepatocytes and endothelial cells during reperfusion.

Topics: Animals; Apoptosis; Atrial Natriuretic Factor; Caspase 3; Caspase Inhibitors; Cell Division; Conditioning, Psychological; Cryopreservation; Cyclic GMP; In Situ Nick-End Labeling; Liver; Necrosis; Organ Preservation; Rats; Rats, Sprague-Dawley

To better understand the mechanism(s) underlying nitric oxide (. NO)-mediated toxicity, in the presence and absence of concomitant oxidant exposure, postmitotic terminally differentiated NT2N cells, which are incapable of producing. NO, were exposed to PAPA-NONOate (PAPA/NO) and 3-morpholinosydnonimine (SIN-1). Exposure to SIN-1, which generated peroxynitrite in the range of 25-750 nM/min, produced a concentration- and time-dependent delayed cell death. In contrast, a critical threshold concentration (>440 nM/min) was required for. NO to produce significant cell injury. Examination of cells by electron microscopy shows a largely necrotic injury after peroxynitrite exposure but mainly apoptotic-like morphology after. NO exposure. Cellular levels of reduced thiols correlated with cell death, and pretreatment with N-acetylcysteine (NAC) fully protected from cell death in either PAPA/NO or SIN-1 exposure. NAC given within the first 3 h posttreatment further delayed cell death and increased the intracellular thiol level in SIN-1 but not. NO-exposed cells. Cell injury from. NO was independent of cGMP, caspases, and superoxide or peroxynitrite formation. Overall, exposure of non-. NO-producing cells to. NO or peroxynitrite results in delayed cell death, which, although occurring by different mechanisms, appears to be mediated by the loss of intracellular redox balance.

Topics: Acetylcysteine; Animals; Cell Death; Cell Differentiation; Cell Line; Cell Survival; Cyclic GMP; Hydrazines; Molsidomine; Necrosis; Neurons; Nitrates; Nitric Oxide; Nitric Oxide Donors; Oxidants; Sulfhydryl Compounds