Effects Of PM_2.5 On Arterial Myogenic Responses In Rats In Taiyuan Iron And Steel Region

Objective?To clarify the pollution level and the chemical composition of airborne fineparticulate matter (PM_2.5) collected from Taiyuan iron & steel factory area. To instruct toepidemiological study on cardiovascular disease (CVD) morbidity and provide basic researchreference to the relevance of PM_2.5 and CVD.Methods?PM_2.5 was collected continuous with TH-1000?intelligent high-capacity air totalsuspended particle no carbon brush sampler, 2.5?m sickle and 22×20cm glass fiber samplingmembrane. The weight of PM_2.5 was calculated by weighing sampling membrane before andafter sampling. The powders of PM_2.5 water-soluble components were freeze-dried in vacuumfrom extracts dissolved in deionized water. The organic component powders were steaming anddried from methylene chloride dissolvent extraction with soxhelt extraction device. The extractedmetal ions were dissolved in nitric acid with soxhelt extraction device and tested the componentwith plasma-atomic emission spectrometry.Results?1. The daily average concentration (102.628 + 48.614?g /m3 air flow) of PM_2.5 in samplingregion was higher significantly than the standard of Environmental Protection Agency (EPA)(35±5.63?g/m3) (P<0.05).2. Compared with the same period of 20 years ago in sampling region, the concentration of Zn inPM_2.5 rises significantly (7.99±0.97 vs 1.31±0.32, P<0.05) while the concentration of Cu(0.10±0.01 vs 0.84±0.17, P<0.05) and Pb (0.20±0.03 vs 1.86±0.13, P<0.05) reduces significantlyand the concentration of Ni and V concentration is similar.3. The organic content of atmospheric PM_2.5 is about 0.162g/g PM_2.5 (16.62±7.58?g/m3 air flow)in sampling region.Conclusions?1. The daily average concentration of PM_2.5 in the sampling region is significantly higher thanthe standard concentration of World Health Organization (WHO) or Environmental ProtectionAgency (EPA).2. Although the concentration of Ni and V in PM_2.5 was unchanged, the concentration of Pb, aheavy metal related to cardiovascular disease, decreased obviously in sampling region. Objective?To observe the effects on vascular reactivity of isolated rat thoracic aortas rings andthe changes about NOS/NO system and Ang?in serum and tissue level by intravenousinjection PM_2.5 (water-soluble, organic and mixture components) in the tail. Explore the possibletoxic mechanism of different components of PM_2.5 to CVD.Methods?Sixty Male Wistar rats were divided into four groups randomly: control group (0.9%sodium chloride, 1 ml·kg-1·d-1, i.v.), water-soluble group (PM_2.5 water-soluble extracts, 1ml·kg-1·d-1, i.v.), organic group (PM_2.5 organic extracts, 1 ml·kg-1·d-1, i.v.), mixtral componentsgroup (PM_2.5 water-soluble extracts, 0.5 ml·kg-1·d-1; PM_2.5 organic extracts, 0.5 ml·kg-1·d-1, i.v.).The PM_2.5 concentration of water-soluble component powders was 6mg/ml. The PM_2.5concentration of organic component powders was 800 ug/ml. Rats were stunned and collectedblood sample after treated 10 days. The thoracic aortas and heart were isolated. The isolatedthoracic aortas ring reactivity was studied. The eNOS and iNOS protein expression of thoracicaortic endothelial cells was observed. The concentration of NO, eNOS , iNOS and Ang?inplasma and myocardium were detected respectively.Results?1. Compared with the control group, there was no significant difference in the thoracic aortasrings contractions induced by KCl(20-120mM) and PE(10-8-10-4mol/L) in PM_2.5 extracts-treatedgroups (P?0.05). Ach (10-9¹0-5mol/L) induced vasorelaxation was attenuated in PM_2.5extracts-treated groups(P?0.05), however SNP (10-9¹0-5mol/L) induced vasorelaxation was notattenuated in PM_2.5 extracts-treated groups (P?0.05).2. Serum NO level was increased significantly in PM_2.5 extracts-treated groups (P < 0.05 vscontrol group), especially in the water-soluble group and mixtral group(P<0.01 vs controlgroup).3.Serum eNOS level decreased significantly in water-soluble and mixture treated group (P?0.01vs control group)?but no significant difference was found in organic treated group (P?0.05 vscontrol group). Serum iNOS level significantly increased in water-soluble and mixture treatedgroup (P?0.01 vs control group)?but no significant difference was found in organic treatedgroup (P?0.05 vs control group).4. The eNOS level of myocardium homogenate had no significant change in PM_2.5extracts-treated groups (P?0.05 vs control group). The iNOS level of myocardium homogenateincreased significantly in water-soluble and organic treated group (P?0.05 vs control group)?however, no significant difference was found in mixtural group (P?0.05 vs control group).5. Serum Ang?level decreased in all PM_2.5 extracts-treated groups (P?0.05 vs control group).Myocardium homogenate Ang?level increased in all PM_2.5 extracts-treated groups(P?0.05 vscontrol group).6. In the endothelial cells from rat thoracic aortas of all PM_2.5 extracts-treated groups the eNOSprotein expression level decreased (P?0.05 vs control group) but iNOS protein expression levelincreased (P?0.05 vs control group). And there were remarkable differences of eNOS and NOSprotein expression level in mixtrue group(P<0.01 vs control group).Conclusions?1. All kinds of PM_2.5 extract exposal weaked the vasodilation of Ach to influence on the vasodilation of SNP and vasoconstriction of KCL and PE.2. Since the eNOS and iNOS protein expression changed in the endothelial cells from ratthoracic aortas, the effect of PM_2.5 on vascular reactivity may be related to endotheliumdysfunction.Objective?To explore the effects on vascular reactivity of isolated rat coronary and coronarysmooth muscle cell voltage-gated potassium channel (kv1.2, kv1.5 and BKCa) by intravenousinjection PM_2.5 (water-soluble, organic and mixture components) in the tail.Methods?Sixty Male Wistar rats were divided into four groups randomly: control group (0.9%sodium chloride, 1 ml·kg-1·d-1, i.v.), water-soluble group (PM_2.5 water-soluble extracts, 1ml·kg-1·d-1, i.v.), organic group (PM_2.5 organic extracts, 1 ml·kg-1·d-1, i.v.), mixtral componentsgroup (PM_2.5 water-soluble extracts, 0.5 ml·kg-1·d-1; PM_2.5 organic extracts, 0.5 ml·kg-1·d-1, i.v.).The PM_2.5 concentration of water-soluble component powders was 6mg/ml. The PM_2.5concentration of organic component powders was 800 ug/ml. Rats were stunned after treated 10days. The coronary was isolated. The isolated coronary was prepared for vascular reactivitystudy partly and detection the mRNA and protein expression of kv1.2, kv1.5 and BKCa.Results?1. Compared with the control group, PM_2.5 in mixture treated group increased coronarycontractions induced by KCl(20-120mM) and U46619(10-8-10-6mol/L) (P<0.05)?but there wasno significant difference in PM_2.5 water-soluble and organic groups (P?0.05).2. The vasorelaxation induced by Ach (10-9¹0-5mol/L) was attenuated in PM_2.5 extracts-treatedgroups(P?0.05 vs control group). Pretreated with 60 mmol/L KCl or 10-6mol/L U46619, theSNP (10-9¹0-5mol/L) induced vasorelaxation was attenuated in PM_2.5 extracts-treated groups(P?0.05 vs control group).3. In PM_2.5 extracts-treated groups, 4-AP(10-3¹0-2mol/L) increased the coronary contractions (P?0.05 vs control group) but TEA (10-5 ³×10-2mol/L) did not infect the coronary contractions(P>0.05 vs control group).4. The mRNA and protein expression of kv1.2 and BKCa in rat coronary smooth muscle cell hadno significant differences after PM_2.5 extracts-treated(P>0.05 vs control group). However, themRNA and protein expression of kv1.5 in rat coronary smooth muscle cell reduced significantlyin all PM_2.5 extracts-treated groups(P<0.05 vs control group).Conclusions: All kinds of PM_2.5 extract exposal induced the change of coronary reactivity.Treated with PM_2.5 extract in vivo, mRNA and protein expression of kv1.5 reduced significantlywhile the mRNA and protein expression of kv1.2 and BKCa had no significant differences in ratcoronary smooth muscle cell.