Atmospheric Fine Particles In Rat Thoracic Aorta Contraction, Diastolic Function And NOS / NO Pathway

Objective: By preparation of endothelium rings of rat thoracic aortas, to observe the effects of WSC of Fine Particulate Materials (PM_2.5) on the contraction and relaxation in isolated rat thoracic aortas and to discuss its possible mechanisms to affect endothelial cells.Methods: Isolated thoracic aortas of 18 Wistar rats were prepared and subjected to the following experiments: 1.the effects of PM_2.5 on the contraction of thoracic aortas in normal rats: the effects of 0μg/ml,10μg/ml,100μg/ml PM_2.5 on the contraction of intact endothelium rings and denude endothelium rings induced by Phenylephrine(PE) at different concentrations; intact endothelium rings being pretreated with superoxide dismutase(SOD) combined with Dimethyl sulphoxide (DMSO), to discuss the influence of pretreatment on effects of 100μg/ml PM_2.5. 2. the effects PM_2.5 on the relaxation of thoracic aortas in normal rats: intact endothelium rings being pre-contracted with 10-6NE, to observe the effects of 0μg/ml,10μg/ml,100μg/ml PM_2.5 on the relaxation of denude endothelium rings induced by ACH at different concentrations, and to discuss the influence of pretreatment with superoxide dismutase(SOD) combined with Dimethyl sulphoxide (DMSO) on effects of 100μg/ml PM_2.5.Results:1. no direct effect of WSC for PM_2.5 at different concentrations on endothelium rings in quiescent condition. 2. PE at 10-5mol/L, concentration rate as 88.04±2.34 for 100μg/ml, higher than 0μg/ml (79.10±7.95) or10μg/ml (80.83±5.41)and SOD+DMSO + PM100(P<0.05或P<0.01);concentration rate of L-NAME+PM100 (96.80±2.21) was higher than 100μg/ml (P<0.05),no significant difference for 0μg/ml and SOD+DMSO+ PM100 (P>0.05). 3. Ach at 10-5mol/L, relaxation rate induced by 100μg/ml PM_2.5 was 36.80±5.41, lower than control. No significant differences were observed among 10μg/ml PM_2.5 (P<0.01),SOD+DMSO +PM_2.5100μg/m and control group (P >0.05).Conclusions: PM_2.5 can markedly promote contraction of PE to endothelium rings and weaken relaxation induced by ACH, with probable mechanism related to oxidative impairment in endothelial cells. Objective: to discuss the difference of concentration and relaxation of thoracic aortas endothelium rings of both normal rats and arteriosclerosis rats, at 1h and 6h after being injected with WSC of PM_2.5.Methods: Male Wistar rats being randomly divided into control group, 1h control group, 6h control group, atherosclerosis group, 1h atherosclerosis group, 6h atherosclerosis group, 10 for each group. For exposure group, 1h or 6h after intravenous injection of WSC of PM_2.5 (1ml/kg), anesthesia with peritoneal injection (0.4ml/100g) of 25% urethan, to prepare endothelium rings with thoracic aortas, put endothelium rings on tonotransducer.Results: 1.successfully prepare atherosclerosis rats models. 2.Comparation of relaxation (1) ACH relaxation: Compared to control group, 6h control group, Ach at 10-5mol/L (10-6MNE pretreatment), relaxation of 1h control group decreased with significant difference (P<0.001); no significant difference on relaxation rate for control group and 6h control group( P>0.05); Ach at 10-5mol/L (precontracted with 60mmol/LKCL), no significant difference among control group, 1h control group and 6h control group; Ach at 10-5mol/L (precontracted with 10-6MNE), compared to atherosclerosis group, relaxation rate of 1h atherosclerosis rats decreased by 32.63% (P<0.01),no significant difference on relaxation rate for 6h atherosclerosis group and atherosclerosis group; Ach at 10-5mol/L(precontracted with 60mmol/LKCL),relaxation rate of 1h atherosclerosis group decreased by 42.72%(P<0.001), no significant difference for 6h atherosclerosis group and atherosclerosis group( P>0.05). (2)SNP relaxation: SNP at 10-5mol/L(precontracted with 10-6MNE),compared to control group (relaxation rate (93.62±3.26)%) and 6h control group (relaxation rate (82.52±6.16)%), relaxation rate of 1h control group dropped to (77.34±9.60)%(P<0.01); no significant difference on relaxation between later groups ( P>0.05);rats in control group precontracted at 60mmol/LKCL, no significant difference on relaxation rate among three groups( P>0.05),atherosclerosis rats precontracted at 10-6MNE or 60 mmol/LKCL, also no significant difference among three groups(P>0.05). 3.comparation of contractile function: thoracic aortas of rats in control group contracted at different PE concentrations, no significant difference on contraction rate among three groups ( P>0.05); for atherosclerosis rats, PE at 10-5mol/L, contraction rate for 1h group was (76.06±19.86)%, higher than atherosclerosis group (54.13±17.44)% and 6h atherosclerosis group (44.80±12.64)% (P<0.05). No significant difference between later two groups ( P>0.05).Conclusions: For normal rats and atherosclerosis rats, 1h after intravenous injection with WSC of PM_2.5, relaxation is weakened. In addition, for atherosclerosis rats 1h after intravenous injection with WSC of PM_2.5, contraction is enhanced, which will be weakened 6h later. The impairment of WSC of PM_2.5 to vascular functions is not only limited to vascular endothelium.Objective: With normal rats and atherosclerosis rats injected by vein in the tail with WSC of PM_2.5, at the basis of 1h after injection, to discuss the effects of WSC of PM_2.5 on NOS-NO system in the endothelial cells from rat thoracic aortasMethods: 40 healthy male Wistar rats, being acclimatized for one week, were divided randomly into 4 groups (10 for each group) as: control group, 1h control group, atherosclerosis group, 1h atherosclerosis group. Experiment was made 12 weeks later. Control group and atherosclerosis group were injected by vein in the tail with saline water (1ml/kg), 1h control group and 1h atherosclerosis group were injected by vein in the tail with WSC of PM_2.5.. l hour after injection , rats were anesthetized with intraperitoneal injection of urethane(0.4ml/100g), carotid spiled on the right, recording waveform of blood pressure and electrocardiogram. Investigating and recording waveform of blood pressure, intercepting 10min of blood pressure and electrocardiogram when stable, to calculate the average of blood pressure and heart rate. After recording, to prepare serum with arterial blood from abdominal aorta, to expose heart before stop beating, to remove aorta to fix and prepare paraffin section. The relevant indicators should be tested after the preparation of specimen.Results: 1.Effects of PM_2.5 on blood pressure and heart rate of normal rats and arteriosclerosis rats. (1) For 1h control group, systolic pressure was higher than control group, (141.12±13.55) mmHg vs (122.24±13.92)mmHg,P<0.05. For 1h arteriosclerosis group, systolic pressure was lower than arteriosclerosis group, (112.86±20.38) mmHg vs (131.50±13.55)mmHg,P<0.05. (2) For 1h control group, heart rate was higher than control group, (377.48±41.45)times/min vs (345.69±38.82) times /min,P<0.05. For 1h arteriosclerosis exposure group, heart rate was lower than arteriosclerosis group, (204.07±23.66)times/min vs( 238.46±32.14) times /min,P<0.05. 2. Effect of PM_2.5 on each item of blood-serum in normal rats and arteriosclerosis rats. (1) For 1h control group, NO level of blood-serum was lower than control group P<0.01. For 1h arteriosclerosis group, NO level of blood-serum was lower than arteriosclerosis group, P<0.05. (2) For 1h control group, iNOS level of blood-serum was higher than control group P<0.01. For 1h arteriosclerosis group, iNOS level of blood-serum was higher than arteriosclerosis group, P<0.05. (3) No significant difference on eNOS level of blood-serum among several groups P>0.05. 3. Effect of PM_2.5 on iNOS, eNOS, Nrf2 proteins on endothelium and the wall under endothelium of blood vessel in normal rats and arteriosclerosis rats. (1) For 1h control group, eNOS protein level of aorta was lower than control group P<0.05;for 1h arteriosclerosis group, eNOS protein of aorta was lower than arteriosclerosis group P<0.05. (2) For 1h control group, iNOs protein level of aorta was higher than control group P<0.05. For 1h arteriosclerosis group, iNOs protein level of the wall under endothelium was higher than arteriosclerosis group P<0.05. (3) For 1h control group, Nrf2 protein level of endothelium and the wall under endothelium in aorta was higher than control group, P<0.05. For 1h arteriosclerosis group, Nrf2 protein level of the wall under endothelium in aorta was higher than arteriosclerosis group, but no significant difference on Nrf2 protein level of endothelium with arteriosclerosis group, P>0.05.Conclusions: Active exposure of WSC of PM_2.5 induces a change of blood pressure and heart rate in both normal rats and atherosclerosis rats, which is related to oxidative stress in mechanism. The disorder of NOS/NO is one of the mechanisms of impairment of PM_2.5 on endothelial cells. PM_2.5 further strengthens the disorder of NOS/NO of endothelial cells in atherosclerosis rats. PM_2.5 induces the activation of antioxidation system in endothelial cells.