|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Nitric Oxide (NO) has two different effects on cells ; protective and detrimental ones. There are reports on these effects after administration of endotoxin (LPS) and tumor necrosis factor. However, it is not clarified which mechanism switch the two different effects on cells. In this study, I tried to clarify the mechanism.
(A) Protective effects :
Examined if harmful effect by LPS can be inhibited by NO.1) A harmful effect of LPS given with actinomycin D on rat hepatocytes was confirmed. 2) Cells viability decreased with addition of iNOS inhibitor to the medium. 3) Addition of 2mM S-nitroso-N-acetylpenicillamine (SNAP) that yields NO to the medium dramatically increased cell viability, inhibited fragmentation of DNA.4) Administration of Rotenone or antimycin A, inhibitors of mitochondrial electron transport, decreased production of reactive oxygen intermediates and DNA fragmentation. 5) Production of reactive oxygen intermediates, which are yielded during mitochondrial electron transport, are suppressed with the administration of SNAP.6) It is considered from the above stated results that reactive oxygen intermediates which are yielded during electron transport in mitochondria contribute to the fragmentation of DNA, and that administration of 2mM SNAP inhibits the process.
(B) Detrimental effects :
When hepatocytes were prepared and incubated with LPS together with Actinomycin D and 2mM of SNAP, cell death rate was suppressed as stated above. Initial preliminary experiments suggested that the rate increased when the concentration of SNAP was increased to 14mM.However, unfortunately data obtained thereafter revealed the preliminary results are unlikely, even though preliminary experiments were repeated vigorously. Therefore, I was not able to clarify the mechanism from tha standpoint of NO concentration.