Interactions of Nitric Oxide and Antioxidants in Hypoxia-Reoxygenation Injury

PURPOSE: An ischemia-reperfusion injury leads to profound functional and structural alterations of vascular smooth muscle cells (VSMC). It is still not clear whether hypoxia- reoxygenation and antioxidants affect the nitric oxide (NO) synthesis of VSMC. This study tried to investigate the effects of antioxidants on NO production, inducible nitric oxide synthase (iNOS) and the expression of NFkappaB p65, during the hypoxia-reoxygenation of VSMC cultures. METHODS: The VSMCs were primarily cultured from rat aortae, and confirmed by immunoreaction with the anti- smooth muscle myosin antibody. The condition of the hypoxia was verified by measuring the PO2 and PCO2 of the culture media. The concentrations of nitrite in the culture media were measured by the Griess reaction. Western blottings for the iNOS and NFkappaB p65 proteins were performed. L-NAME was used as an NOS inhibitor. Vitamins C and E, Glutathione (GSH), lipoic acid and dihydrolipoic acid (DHLA) were used as antioxidants. RESULTS: The iNOS protein was induced in the VSMC by 24 hours of hypoxia, which increased the nitrite in the VSMC culture medium. The reoxygenation profoundly increased the iNOS protein expression and nitrite concentration. The L- NAME, vitamins C and E, GSH, lipoic acid and DHLA decreased the nitrite productions during hypoxia and the hypoxia-reoxygenation, whereas, the expressions of the iNOS and NFkappaB p65 proteins were not influenced. CONCLUSION: We concluded that hypoxia-reoxygenation induced the iNOS protein, and the subsequent production of NO in the VSMC. The antioxidants and the NOS inhibitor decreased the NO production during the hypoxia-reoxygenation, but did not affect the expressions of the iNOS and NFkappaB p65 proteins

The Effects of Anticholinesterase Drugs on Gastric Motility / 영남의대학술지

BACKGROUND: Anticholinesterase drug inhibits acetylcholinesterase(AChE), induce accumulation of acetylcholine(ACh) near cholinergic receptors and cholinergic stimulation. This experiment was performed to study the effects of anticholinesterase drugs on gastric motility and the effect of ethanal on anticholinesterase drug-induced motility change. MATERIALS AND METHODS: After excision of stomach, 2x10mm circular musele strips were made, which were then fixed to the isolated muscle chamber. An isometric tension transducer was used to measure the contraction change of the gastric smooth muscle strips after drug addition. RESULTS: Fenthion, and irreversible anticholinesterase drug, increased ACh induced contraction of gastric smooth muscle strips and PAM, a cholinesterase activator, antagnized this action. Physostigmine, a reversible anticholinesterase drug, also increased the ACh induced contraction. The gastric motility was decreased by PAM. Ethanol, which is known to induce smooth muscle relaxation, inhibited the increase of contraction by fenthion. CONCLUSION: These results indicate that irreversible and reversible anticholinesterase drugs increase gastric motility and antagonized by cholinesterase activating drugs. And when exposed to both ethanol and anticholinesterase drug, gastric motility was decreased by the smooth muscle relaxation effect by ethanal.

The Effects of Ethanol on Cholinesterase Inactivation by Organophosphorous / 영남의대학술지

BACKGROUND: In korea the agricultural community widely uses organophosphorous, and organophosphorous poisonings are increasing every year. We compared change in activity of acetylcholinesterase and pseudocholinesterase by organophosphorous and by the interaction of ethanol and organophosphorous. We also compared the effect of reversible anticholinesterase drugs, physostigmine and neostigmine. The object of this study is to investigate the effects of several anticholinesterase drugs and on how ethanol influences the activity of cholinesterase. MATERIALS AND METHODS: Fifteen male university students were randomly selected, and blood samples were taken from the antecubital vein. The acetylcholinesterase in the RBC and the pseudocholinesterase in the serum were extracted and separated. The enzyme activity change was measured by the electrometric method. After adding acetylcholine, the pH change was measured with a pH meter. RESULTS AND CONCLUSION: Our results indicated that reversible anticholinesterase drugs decreased the cholinesterase activity more efficiently than organophosphorous. The acetyl cholinesterase and pseudocholinosterase activity were decreased by ethanol. When ethanol was added, oxime a cholinesterase activator, increased acetylcholinesterase activity but dose not increased pseudocholinesterase activity.

Effect of Guanylate Cyclase Inhibition on the Concentration of Nitrite in Culture Medium of Vascular Smooth Muscle Cell

PURPOSE: Nitric oxide (NO) exerts the relaxant effect in vascular smooth muscle cells (VSMC) by activating soluble guanylate cyclase (sGC), which produces cyclic guanidine monophosphate (cGMP) in the cell. This study was undertaken to investigate the mechanism of the inhibitory actions of sGC inhibitors, LY 83583 and methylene blue in the VSMC. METHODS: VSMC was primarily cultured from rat aorta and confirmed by immunocytochemistry of anti-smooth muscle myosin antibody. Bacterial lipopolysacchride (LPS), an inducer of inducible nitric oxide synthase (iNOS) and sodium nitroprusside (SNP), an NO donor, were uesd to increase NO within VSMC. The changes in concentrations of nitrite in culture media by an addition of LPS or SNP with a pretreatment of LY 83583 or methylene blue were measured by the spectrophotometry with griess regent and absorbance at 550 nm. Western blot and RT-PCR for iNOS and iNOS mRNA, respectively were performed. RESULTS: LPS and SNP increased nitrite concentration. LY 83583 potentiated the increase in nitrite concentration by LPS and SNP. LY 83583 also increased expressions of iNOS protein and mRNA induced by LPS. Methylene blue has no effect on nitrite concentration increased by LPS or SNP, and it did not affect the expressions of iNOS protein or mRNA induced by LPS. CONCLUSION: These results suggest that the mechanism of inhibitory actions of LY83583 and methylene blue on sGC are different each other: LY83583 interferes the interaction of sGC and NO resulting positive feedback increase in iNOS gene expression, but methylene blue eliminates NO from cytosol inducing no compensatory effect.