Evaluation of the hepatic reduction of a nitroxide radical in rats receiving ascorbic acid, glutathione or ascorbic acid oxidase by in vivo electron spin resonance study

Abstract

Ascorbic acid administration directly increases hepatic reducing ability. Ascorbic acid, which increased in the plasma due to GSH administration, entered the liver and enhanced the hepatic reducing ability. Administration of AAOx impaired the hepatic reducing ability by oxidizing AsA in the plasma and/or the liver.

Evaluation of Antioxidative Effects of Sesamin on the In vivo Hepatic Reducing Abilities by a Radiofrequency ESR Method

“…When peak-to-peak line width of the ESR signal of TEMPOL exhibits no temporal changes in a target organ, the peak-to-peak height can then be used as the signal intensity. [16][17][18][19][20] In the target organs, changes in the signal intensity correspond to changes in the TEMPOL concentration. When there is good linearity in a semi-logarithmic plot of the signal intensity with high reproducibility after a TEMPOL injection, this is indicative of the pseudo-first-order kinetics of the TEMPOL decrease in the target organ.…”

“…The half-lives of TEMPOL in the target organs were used as the parameter to estimate the decay rate of TEMPOL, as this parameter was not influenced by reduction in the other organs. 17,18 After the TEMPOL injection, the half-lives were calculated using the linear regression from the initial phase of the semi-logarithmic plots of the signal intensity against time.…”

“…[16][17][18] The SCR consisted of a single-turn coil (f = 10 mm) and transmission lines that were formed by the flexible coaxial cables. 15 The SCR was connected to the microwave circuit through a three-stub tuner and driven at a resonant frequency of approximately 720 MHz.…”

“…16,17 Although we observed that ascorbic acid (AsA), which can directly reduce TEMPOL, could enhance TEMPOL reductions in the rat liver in vivo, we additionally found that intravenous administration of AsA oxidase led to a decrease. 18 Moreover, even though reduced glutathione (GSH) did not directly reduce TEMPOL in vitro, GSH administration did increase the in vivo hepatic reducing ability of TEMPOL. 18 In addition, we have further confirmed that GSH can recycle AsA from dehydroascorbic acid (dehydro-AsA) and suppress AsA consumption in vivo.…”

“…18 Moreover, even though reduced glutathione (GSH) did not directly reduce TEMPOL in vitro, GSH administration did increase the in vivo hepatic reducing ability of TEMPOL. 18 In addition, we have further confirmed that GSH can recycle AsA from dehydroascorbic acid (dehydro-AsA) and suppress AsA consumption in vivo. When taken together, these findings indicate that AsA and AsA recycling from dehydro-AsA may play a crucial role in the reduction of TEMPOL via the electron transfer systems in the hepatic organelles and cell membranes.…”