Hypertonic saline and reduced peroxynitrite formation in experimental pancreatitis

OBJECTIVES: In this study, we tested the hypothesis that hypertonic saline exerts anti-inflammatory effects by modulating hepatic oxidative stress in pancreatitis. INTRODUCTION: The incidence of hepatic injury is related to severe pancreatitis, and hypertonic saline reduces pancreatic injury and mortality in pancreatitis. METHODS: Wistar rats were divided into four groups: control (not subjected to treatment), untreated pancreatitis (NT, pancreatitis induced by a retrograde transduodenal infusion of 2.5 percent sodium taurocholate into the pancreatic duct with no further treatment administered), pancreatitis with normal saline (NS, pancreatitis induced as described above and followed by resuscitation with 0.9 percent NaCl), and pancreatitis with hypertonic saline (HS, pancreatitis induced as described above and followed by resuscitation with 7.5 percent NaCl). At 4, 12, and 24 h after pancreatitis induction, liver levels of inducible nitric oxide synthase (iNOS), heat-shock protein 70, nitrotyrosine (formation of peroxynitrite), nitrite/nitrate production, lipid peroxidation, and alanine aminotransferase (ALT) release were determined. RESULTS: Twelve hours after pancreatitis induction, animals in the HS group presented significantly lower iNOS expression (P<0.01 vs. NS), nitrite/nitrate levels (P<0.01 vs. NS), lipid peroxidation (P<0.05 vs. NT), and ALT release (P<0.01 vs. NS). Twenty-four hours after pancreatitis induction, nitrotyrosine expression was significantly lower in the HS group than in the NS group (P<0.05). DISCUSSION: The protective effect of hypertonic saline was related to the establishment of a superoxide-NO balance that was unfavorable to nitrotyrosine formation. CONCLUSIONS: Hypertonic saline decreases hepatic oxidative stress and thereby minimizes liver damage in pancreatitis.

The Role of Nitric Oxide in Ocular Surface Cells

The role of nitric oxide (NO) in the ocular surface remains unknown. We investigated the conditions leading to an increase of NO generation in tear and the main sources of NO in ocular surface tissue. We evaluated the dual action (cell survival or cell death) of NO depending on its amount. We measured the concentration of nitrite plus nitrate in the tears of ocular surface diseases and examined the main source of nitric oxide synthase (NOS). When cultured human corneal fibroblast were treated with NO producing donor with or without serum, the viabilities of cells was studied. We found that the main sources of NO in ocular surface tissue were corneal epithelium, fibroblast, endothelium, and inflammatory cells. Three forms of NOS (eNOS, bNOS, and iNOS) were expressed in experimentally induced inflammation. In the fibroblast culture system, the NO donor (SNAP, S-nitroso-N-acetyl-D, L-penicillamine) prevented the death of corneal fibroblast cells caused by serum deprivation in a dose dependent manner up to 500 micrometer SNAP, but a higher dose decreased cell viability. This study suggested that NO might act as a doubleedged sword in ocular surface diseases depending on the degree of inflammation related with NO concentration.