[Involvement of heme oxygenase in PM2.5-toxicity in human umbilical vein endothelial cells].

OBJECTIVE: To investigate the involvement of heme oxygenase (HO-1) in PM2.5 induced toxic responses in human umbilical vein endothelial cells (HUVECs). METHODS: The experiment groups are as follows: (1) control group; (2) PM2.5 groups: the cells were cultured with various concentrations of PM2.5 (200, 400, 800 µg/ml) for 24 h and 400 µg/ml was chosen for the main study; (3) PM2.5+Trion group: the cells were pre-treated by 10 µmol/L Trion [a scavenger of reactive oxygen species(ROS)] for 1 h before PM2.5 (400 µg/ml) treatment for 24 h; (4) PM2.5+ZnPP group: the cells were pretreated by HO-1 inhibitor ZnPP (10 µmol/L) for 1 h before treatment with PM2.5 (400 µg/ml) for 24 h. MTT assay was used to detect cell viability. Reverse transcription polymerase chain reaction (RT-PCR) and indirect immunofluorescence assay were used to determine the mRNA and protein expressions of HO-1. Fluorescence labeling probe method was used to measure intracellular ROS level and flow cytometry was used for cell apoptosis. Colorimetric assay was used to detect intracellular caspase-3 activity. RESULTS: Compared with control, PM2.5 significantly decreased cell viability, increased intracellular ROS, cell apoptosis and caspase-3 activity (all P < 0.05), these effects were significantly attenuated in PM2.5+Tiron group while enhanced in PM2.5+ZnPP group (all P < 0.05 vs. PM2.5 group). PM2.5 upregulated HO-1 mRNA and protein expressions in HUVECs which was downregulated in both PM2.5+Tiron group and PM2.5+ZnPP group. CONCLUSION: PM2.5 could induce oxidative injury through increasing ROS production via modulating HO-1 mRNA and protein expressions, the injury could be aggravated with inhibition of the activity of HO-1 suggesting a potential protective role of HO-1 against PM2.5 induced oxidative stress in HUVECs.

[Effect of ginsenoside on fine particulate matter induced oxidative injury in human endothelial cells].

OBJECTIVE: To explore the mechanism of fine particulate matter (PM(2.5)) induced endothelial injury and the efficacy and mechanism of ginsenoside Rg1 on the inhibition of endothelium injuries in human endothelial cells exposure to PM(2.5). METHODS: Human umbilical vein endothelial cells (HUVECs) were stimulated with various concentrations PM(2.5) (0.1, 0.2, 0.4, 0.8 mg/ml) and PM(2.5) at concentration 0.8 mg/ml induced significant endothelial injury and was chosen for the main study in the presence or absence of Rg1 (0.04 mg/ml). After 24 h treatment, cell growth A value was detected through MTT, intracellular reactive oxygen species (ROS) level through fluorescence labeling probe method and HO-1, Nrf2 mRNA expression was detected by RT-PCR. RESULTS: The cell A value was significantly lower while the ROS fluorescence gray value and the average optical density ratio of HO-1 were significantly higher in PM(2.5) group than in the control group (all P < 0.05). The average optical density ratio of Nrf2 was similar between PM(2.5) group and control group (P > 0.05). The A value and the average optical density ratio of HO-1 were significantly higher while the ROS fluorescence gray value was significantly lower in co-treated PM(2.5) (0.8 mg/ml) + Rg1 (0.04 mg/ml) group than in the PM(2.5) (0.8 mg/ml) group (all P < 0.05). CONCLUSION: PM(2.5) could induce human endothelial cells injury by increasing oxidative stress which could be attenuated by ginsenoside Rg1.

[The comparison study on effects of water-soluble components of fine particulate matter on vasomotor functions in aortas from rats after exposure in different time].

OBJECTIVE: To compare the difference of vasomotor functions in aortas segments from Wistar rats between 1-hour and 6-hours after exposure of water-soluble components of fine particulate matter (PM2.5). METHODS: All 30 Wistar rats were assigned to five groups (n=6 for each group) at random: the blank control group, control group for 1-hour and 6-hours, exposure group for 1-hour and 6-hours. The rats were sacrificed 1-hour or 6-hours later and aorta ring segments were mounted on wire myographs. RESULTS: (1) There was no significant difference in vasomotor functions among three control groups (P>0.05). (2) 1-hour or 6-hours after exposure there was a decrease of contraction elicited by 60 mmol/L KCl in contrast to the control group (P<0.05), whereas no significant change between the exposure group for 1-hour and 6-hours (P>0.05). (3) On the level of 10(-5) or 10(-7) mol/L, 1-hour after exposure there was a decrease in endothelium-dependent acetylcholine (ACh) elicited relaxation precontracted by 10(-6) mol/L NE compared with the control group (P<0.01 or P<0.05), on the level from 10(-5) to 10(-7) mol/L there was a decrease compared with the exposure group for 6-hours (P<0.05), whereas no difference between the exposure group for 6-hours and the control group (P>0.05). On the level from 10(-5) to 10(-9) mol/L, 1-hour after exposure there was a decrease in endothelium-independent sodium nitroprusside (SNP) elicited relaxation precontracted by 10(-6) mol/L NE as compared with the control group (P<0.01 or P<0.05) and a decrease on the level of 10(-6) or 10(-9) mol/L compared with the exposure group for 6-hours (P<0.05), 6-hours after exposure a decrease was caused as compared with the control group on the level from 10(-5) to 10(-7) mol/L (P<0.01 or P<0.05). CONCLUSIONS: Inhibition of contraction and impairment of relaxation in aortas should be caused 1-hour after exposure to water-soluble components of PM2.5 in the air, which is weaken 6-hours after exposure.

[Study of effects of drugs on myocardial hypertrophy due to overload].

OBJECTIVE: To study the relation of expression change of tumor necrosis factor-alpha (TNF-alpha), angiotensin II (Ang II), and endothelin-1 (ET-1), and the effect of imidapril on myocardial hypertrophy due to overload. METHODS: Sixty-three rats were randomly divided into four groups: sham operation (n=15), overload group (n=16), imidapril group (n=16), and Caweidiluo group (n=16). Hypertrophic myocardium was reproduced in rats by constricting abdominal aorta. Blood samples and heart were harvested 12 weeks after aorta constriction, and myocardial hypertrophy index, the contents of Ang II, ET-1 in the myocardium and plasma were determined by radioimmunoassay and TNF-alpha in the myocardium and plasma were determined by enzyme linked immunoadsorbent assay. RESULTS: Left ventricle showed obvious hypertrophy 12 weeks after operation. The contents of TNF-alpha, Ang II and ET-1 in the myocardium, and the content of TNF-alpha in serum, Ang II and ET-1 in plasma were increased compared with those of controls (all P<0.01). The treatment of imidapril and Caweidiluo could restrain the development of left ventricle hypertrophy after operation, and imidapril decreased the contents of TNF-alpha, Ang II and ET-1 in myocardium compared with overload group (all P<0.01). Imidapril lowered the contents of TNF-alpha in serum, Ang II and ET-1 in plasma, compared with overload group (all P<0.01), but not ET-1. Caweidiluo lowered the contents of TNF-alpha, Ang II and ET-1 in myocardium, the contents of TNF-alpha in serum, Ang II and ET-1 in plasma (all P<0.01) compared with overload group (both P<0.01). CONCLUSION: The activation of rennin-angiotensin system (RAS) by over load results to an elevation of TNF-alpha contents in plasma and myocardium, and it is probably one of the major regulatory pathways of myocardial hypertrophy.

Inotropic effects of MCI-154 on rat cardiac myocytes.

Calcium sensitizers exert positive inotropic effects without increasing intracellular Ca(2+). Thus, they avoid the undesired effects of Ca(2+) overload such as arrhythmias and cell injury, but most of them may impair myocyte relaxation. However, MCI-154, also a calcium sensitizer, has no impairment to cardiomyocyte relaxation. To clarify the underlying mechanisms, we examined the effects of MCI-154 on Ca(2+) transient and cell contraction using ion imaging system, and its influence on L-type Ca(2+) current and Na(+)/ Ca(2+) exchange current with patch clamp technique in rat ventricular myocytes as well. The results showed that: (1) MCI-154 (1-100 micromol/L) had no effect on L-type Ca(2+) current; (2) MCI-154 concentration-dependently increased cell shortening from 5.00+/-1.6 microm of control to 6.2+/-1.6 microm at 1 micromol/L, 8.7+/-1.6 microm at 10 micromol/L and 14.0+/-1.4 microm at 100 micromol/L, respectively, with a slight increase in Ca(2+) transient amplitude and an abbreviation of Ca(2+) transient restore kinetics assessed by time to 50% restore (TR(50)) and time to 90% restore (TR(90)); (3) MCI-154 dose-dependently increased the electrogenic Na(+)/ Ca(2+) exchange current both in the inward and the outward directions in rat ventricular myocytes. These results indicate that MCI-154 exerted a positive inotropic action without impairing myocyte relaxation. The stimulation of inward Na(+)/ Ca(2+) exchange current may accelerate the Ca(2+) efflux, leading to abbreviations of TR(50) and TR(90) in rat myocytes. The findings suggest that the improvement by MCI-154 of myocyte relaxation is attributed to the forward mode of Na(+)/ Ca(2+) exchange.

Inhibition of Na+/Ca2+ exchange by hexapeptide FRCRSFa in rat ventricular myocytes.

AIM: To study the effect of Phe-Arg-Cys-Arg-Ser-Phe-CONH2 (FRCRSFa) on Na+/Ca2+ exchange and its specificity in rat ventricular myocytes. METHODS: Na+/Ca2+ exchange current (INa+/Ca2+) and other currents were measured using whole-cell voltage clamp technique. RESULTS: A concentration-dependent inhibition of hexapeptide FRCRSFa on Na +/Ca2+ exchange was observed in rat ventricular myocytes. IC50 of inward and outward INa+/Ca2+ were 2 and 4 micromol/L, respectively. FRCRSFa 5 micromol/L did not affect L-type Ca2+ current, voltage-gated Na+ current, transient outward K+ current, and inward rectifier K+ current. CONCLUSION: These data indicate that FRCRSFa is an available inhibitor of Na+/Ca2+ exchange with relative selectivity and m ay be valuable for studies of the Na+/Ca2+ exchange in cardiac myocytes.