| Background and ObjectivesAtherosclerosis has been recognized as the chief cause of cardiovascular andcerebrovascular diseases. It is now clear that atherosclerosis is not simply an inevitabledegenerative consequence of ageing, but rather a chronic inflammatory condition that canbe converted into an acute clinical event by plaque rupture and thrombosis. There are threemajor anti-atherosclerosis mechanisms, circulating progenitor cells, angiogenesis, andreverse cholesterol transport (RCT). RCT now have been widely recognized as the mostimportant progress in anti-atherosclerosis. RCT refers to a process of promotes the efflux ofexcess cholesterol from peripheral tissues and returns it to the liver for biliary excretion.Long-term L type calcium channel blocker (Ca2+channel blocker, CCB) has usuallyused as an antihypertensive drug, but now proved has effect of anti-atherosclerosis. It hasbeen well-recognized that nifedipine can be used safely for the long-term treatment ofpatients with coronary disease and angina pectoris because, in addition to relievingsymptoms of angina, it prolongs cardiovascular event and procedure free survival. As aconventional calcium channel blocker, nifedipine now has been shown to improvecirculation of coronary artery and vascular endothelial function.However, the underlying mechanisms of CCB anti-atherosclerosis is still unclear. Toinvestigate whether nifedipine anti-atherosclerosis through increasing macrophage reversecholesterol transport, we examined the RAW264.7macrophage reverse cholesteroltransport in ApoE-/-mice and the expression of related genes and protein.Methods1. Sixteen eight-week male ApoE-/-mice were randomly divided into two groups:control group and nifedipine group. All the mice fed with high fat and high cholesterol diet(0.15%cholesterol,10%fat). Nifedipine group were treated with nifedipine (10mg/Kg/d),and control group treated with40%ethanol. Each group treated14days. RAW264.7 macrophage incubated in37℃、5％CO2、DMEM medium with10%FBS.2. RAW264.7macrophages were loaded with cholesterol by incubation withacetylated-LDL, labeled with[3H]-cholesterol, and then intraperitoneally injected into mice.Blood was collected in24h、48h after injection and all concentrations of plasma lipids(TC,TG, LDL and HDL)were measured by Biochemistry Analyzer.3. Tissues and feces were collected in48hours after injection.24h,48h plasma wereanalyzed for tracer counts using a liquid scintillation counter. Feces samples after injection48h were collected and rehydrated in95%ethanol, saponified in10N NaOH. Aftercentrifugation at1200rmp for5min, separated the liquid phase and dried down under N2.Then analyzed for tracer counts using a liquid scintillation counter.4. Liver and small intestine were collected from each mouse and the reversecholesterol transportation related mRNA, including ABCA1, ABCG1, SR-BI and LXRαwere assayed by quantitative real-time PCR; reverse cholesterol transportation relatedproteins, including ABCA1, ABCG1, SR-BI and LXRα were assayed by western blottechniques.Results:1. The plasma TC, TG, HDL-C, LDL-c in nifedipine group were16.99mmol/L、1.35mmol/L、0.95mmol/L、4.61mmol/L respectively; in control group were17.14mmol/L、1.37mmol/L、0.94mmol/L，4.46mmol/L respectively. The plasma TC, TG, HDL-C, LDL-cin nifedipine group have no significant change between the nifedipine group and controlgroup(P>0.5).2. The amount of [3H]-tracer in the24h、48h plasma were in nifedipine group7021,5678; in control group were4422,4388; the amout of [3H]-tracer in the24h、48h plasmawere in nifedipine group were37.02%、22.72%higher than in control group respectively;the amout of48hours feces in nifedipine group was27071, in control group was15383, theamout of48hours feces was43.18%higher than in control group in48hours feces (P<0.5).3. The expression of related genes including ABCA1, ABCG1, SR-BI and LXRα wereall significantly higher in nifedipine group than in the control group.4. The expression of related protein including ABCA1, ABCG1, SR-BI and LXRαwere all significantly higher in nifedipine group than in the control group. Conclusions1. Nifedipine have no significant effect on the plasma concentration of TG, TC,HDL-C, LDL-c.2. Nifedipine enhance ApoE-/-mice RAW264.7macrophage reverse cholesteroltransport.3. Nifedipine increase the expression of related genes including ABCA1, ABCG1,SR-BI through regulating of LXRα in ApoE-/-mice.4. Nifedipine increase the expression of related proteins including ABCA1, ABCG1,SR-BI through regulating of LXRα in ApoE-/-mice. |
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