Reactive oxygen species scavenger protects cardiac cells against injuries induced by chemical hypoxia / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the protective effect of reactive oxygen species (ROS) scavenger, N-acetyl-L-cysteine (NAC), against H9c2 cardiomyocytes from injuries induced by chemical hypoxia.</p><p><b>METHODS</b>H9c2 cells were treated with cobalt chloride (CoCl2), a chemical hypoxia-mimetic agent, to establish the chemical hypoxia-induced cardiomyocyte injury model. NAC was added into the cell medium 60 min prior to CoCl2 exposure. The cell viability was evaluated using cell counter kit (CCK-8), and the intercellular ROS level was measured by 2', 7'- dichlorfluorescein-diacetate (DCFH-DA) staining and photofluorography. Mitochondrial membrane potential (MMP) of the cells was observed by Rhodamine123 (Rh123) staining and photofluorography, and the ratio of GSSG/ (GSSG+GSH) was calculated according to detection results of the GSSG kit.</p><p><b>RESULTS</b>Exposure of H9c2 cardiomyocytes to 600 micromol/L CoCl2 for 36 h resulted in significantly reduced cell viability. Pretreatment with NAC at the concentrations ranging from 500 to 2000 micromol/L 60 min before CoCl2 exposure dose-dependently inhibited CoCl2-induced H9c2 cell injuries, and obviously increased the cell viability. NAC at 2000 micromol/L obviously inhibited the oxidative stress induced by CoCl2, decreased the ratio of GSSG/(GSSG+GSH), increased ROS level, and antagonized CoCl2-induced inhibition on MMP.</p><p><b>CONCLUSION</b>NAC offers obvious protective effect on H9c2 cardiomyocytes against injuries induced by chemical hypoxia by decreasing in the ratio of GSSG/(GSSG+GSH) and ROS level and ameliorating MMP.</p>

Inhibition of 8-OH-DPAT on spontaneous unit discharges of 5-hydroxytryptamine inhibitory unit in rat primary somatosensory cortex / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of 5-hydroxytryptamine (5-HT) on spontaneous unit discharges of primary somatosensory cortex (SI-SUD) and the role of 5-HT1A receptor in 5-HT inhibitory effect on SI-SUD in rat.</p><p><b>METHODS</b>The SI-SUD was recorded before and during microiontophoresis of 5-HT and 8-OH-DPAT (the selective agonist for 5-HT1A receptor. The changes of mean of interspike interval (MISI) of SI-SUD were analysed and handled with the statistics.</p><p><b>RESULTS</b>(1) Effects of 5-HT on SI-SUD may be inhibitory (48/96), excitatory (26/96) or non-responsive (22/96), and the major effect is inhibitory. (2) In 20 of 5-HT inhibited units, 17 are also inhibited with microiontophoresis of 8-OH-DPAT, but 3 have no obvious response to 8-OH-DPAT.</p><p><b>CONCLUSION</b>The major effect of 5-HT on SI-SUD is inhibitory. In majority of 5-HT inhibited units, 5-HT1A receptor may be existence, which may involve in the inhibition of 5-HT on SI-SUD.</p>

Hydrogen peroxide preconditioning protects PC12 cells against apoptosis induced by oxidative stress / 生理学报

Oxidative stress can induce significant cell death by apoptosis. We explore whether prior exposure to H2O2 (H2O2 preconditioning) protects PC12 cells against the apoptotic consequences of subsequent oxidative damages and what role the ATP-sensitive potassium (K(ATP)) channels play in the preconditioning protection. PC12 cells were preconditioned with 90 min exposure to H2O2 at 10 micromol/L, followed by 24-h recovery and subsequent exposures to different concentrations (20, 30, 50 and 100 micromol/L) of H2O2 for 24 h respectively. We used PI staining flow cytometry (FCM) to observe the apoptosis of PC12 cells. It was shown that 24-h exposures to H2O2 at 20, 30, 50 and 100 micromol/L respectively induced substantial cell apoptosis, which was greatly prevented in the preconditioning cells, indicating that H2O2 preconditioning protected PC12 cells against apoptosis induced by H2O2. Administration of pinacidil (10 micromol/L), an K(ATP) channel activator, significantly attenuated the apoptosis of PC12 cells induced by H2O2 at 30 and 50 micromol/L for 24 h respectively. Glybenclamide (10 micromol/L), a K(ATP) channel inhibitor, significantly suppressed or abolished the protective effects caused by the pinacidil but not by H2O2 preconditioning. However, when both H2O2 preconditioning and pinacidil were co-applied, their protection against the apoptosis of PC12 cells was much stronger than that of the individual one of them. These results suggest that H2O2 preconditioning protects PC12 cells against apoptosis and that the activation of K(ATP) channels is not involved in, but synergetically enhances adaptive protection of H2O2 preconditioning.