| PartⅠ :Study of renal and pancreatic microcirculation dysfunction in spontaneously hypertensive ratsObjects:To investigate the changes of renal and pancreatic microcirculation function in spontaneously hypertensive rats(SHRs).Methods:The renal and pancreatic microcirculation function of 8-week-old SHRs and normotensive control Wistar Kyoto rats(WKYs)(n=6 each group)were determined by dual-channel laser Doppler blood perfusion monitoring system.Wavelet transform analysis was performed to compare the spectral characteristics of renal and pancreatic microcirculation and the amplitudes of nitric oxide(NO)-dependent and NO-independent microvascular endothelial components in the microcirculatory blood perfusion signals between two groups.Results:SHRs exhibited decreased renal and pancreatic microvascular blood perfusion compared with WKYs(P<0.05,P<0.01).Kidney and pancreas of WKYs and kidney of SHRs represent stable and regular microvascular vasomotion,while the bio-rhythmic of pancreatic microvascular vasomotion was disarranged in SHRs.The amplitude and frequency of microvascular vasomotion were both decreased in kidney and pancreas of SHRs(P<0.05 or P<0.01).Besides,the amplitudes of NO-dependent and NO-independent endothelial components of kidney and pancreas in SHRs were significantly reduced than that in WKYs(P<0.05 or P<0.01).Conclusions:Renal and pancreatic microcirculation are abnormal in SHRs,manifested by decreased microcirculatory blood perfusion and impaired microvascular vasomotion.Part Ⅱ:Dynamic changes of organ microcirculation dysfunction in the progression of hypertension in SHRsObjects:To investigate the dynamic changes of organic microcirculation function in the progression of hypertension by assessing microcirculatory function of important affected target organs(brain,kidney,pancreas,ear and toe)in 5-,8-,13-and 18-week-old SHRs.Methods:Cerebral,renal,pancreatic,ear and toe microcirculatory blood distribution pattern and microvascular vasomotion of SHRs and WKYs(n=6 each group)at 5,8,13 and 18 weeks were determined.Wavelet transform analysis was performed to analyze the spectrum characteristics of cerebral,renal,pancreatic,ear and toe microcirculation and compare the amplitudes of NO-dependent and NO-independent endothelial components between two groups at different ages.Results:WKYs exhibited high blood distribution pattern and stable and regular microvascular vasomotion of target organs at different weeks,while 8-to 18-week-old SHRs showed low cerebral microvascular blood distribution pattern,and low renal,pancreatic,ear and toe microvascular blood distribution pattern were observed in SHRs at all weeks.18-week-old renal and 5-to 18-week-old cerebral,pancreatic,ear and toe microvascular vasomotion were disarranged.Compared with WKYs,SHRs exhibited decreased cerebral microcirculatory blood perfusion,and reduced amplitude,frequency and relative velocity of microvascular vasomotion,and reduced amplitudes of NO-dependent and NO-independent endothelial components at 8 to 18 weeks(P<0.05 or P<0.01),and functional parameters of microcirculation were gradually decreased with the increase of blood pressure.Renal microcirculation blood perfusion was decreased at 5 weeks(the normotensive stage),and renal microvascular blood perfusion of 8-and 13-week-old SHRs,which were lower than that in WKYs,were higher than that of SHRs in the normotensive stage,18-week-old SHRs exhibited significantly reduced blood perfusion.The amplitude and relative blood velocity represented the same trend of microcirculation blood perfusion in SHRs at all weeks,renal frequency of 13-and 18-week-old SHRs were significantly decreased(P<0.05 or P<0.01).In addition,the amplitudes of NO-dependent and NO-independent endothelial components in 5-to 18-week-old SHRs were significantly lower than that in WKYs(P<0.05 or P<0.01).Pancreatic microcirculatory blood perfusion and amplitude,frequency and relative velocity of microvascular vasomotion,and the amplitudes of NO-dependent and NO-independent endothelial components of microcirculation blood perfusion signals were significantly decreased in SHRs compared with WKYs(P<0.05 or P<0.01),microcirculatory blood perfusion and relative blood velocity were decreased even in the normotensive stage,and functional parameters of microcirculation were gradually decreased with the increase of blood pressure.Compared with WKYs,ear microcirculatory blood perfusion of 5-to 18-week-old SHRs and toe microcirculatory blood perfusion of 5-,8-and 18-week-old SHRs were significantly reduced.Significant decrease and irregular changes of amplitude,frequency and relative velocity of ear and toe microvascular vasomotion were observed in SHRs(P<0.05 or P<0.01).the amplitude of ear NO-independent endothelial oscillator was significantly reduced only in 5-week-old SHRs(P<0.01),and the amplitude of toe NO-dependent endothelial oscillator was significantly decreased in 5-and 8-week-old SHRs(P<0.01,P<0.05).Conclusions:Decreased microcirculatory blood perfusion and impaired microvascular vasomotion of target organs(brain,kidney,pancreas)were observed in the progression of hypertension.There are differences in the time nodes of the initial microcirculatory dysfunction of different organs,different changes of cerebral,renal and pancreatic microcirculation function were found with the increase of blood pressure,and microcirculation dysfunction may be involved in the microcirculatory pathogenesis of hypertension.Although peripheral organs existed pathological phenotypes of microcirculatory dysfunction,but the functional status of microcirculation showed irregular changes with the increase of blood pressure.In addition,the activity of microvascular endothelial cell oscillator was decreased,manifested by reduced amplitude of microvascular endothelial component.Part Ⅲ:Study of molecular mechanism of microvascular endothelial cell dysfunction in SHRsObjects:The possible molecular mechanism of microvascular endothelial cell dysfunction was investigated by detecting the expressions of functional proteins associated with microvascular endothelial cell,vasoconstrictor and vasodilator,oxidative stress markers,inflammatory factors and the levels of tight junction proteins in microvascular endothelial cells.Methods:Renal tissue and plasma samples of male SHRs and WKYs(n=6 each group)at 5,8,13 and 18 weeks were separated.The expressions of eNOS,VCAM-1,PEC AM-1,Claudin,Occludin and ZO-1 in glomerular capillaries of all groups were assessed by immunohistochemistry.Plasma nitrite and nitrate levels were measured using Griess reaction,and endothelin-1(ET-1),superoxide dismutase(SOD),malondialdehyde(MDA),interleukin-6(IL-6)levels were determined by ELIS As.Results:Compared with WKYs,SHRs exhibited decreased expression of eNOS in kidney at all weeks,13-and 18-week-old SHRs expressed significant increased plasma nitrite and nitrate,and plasma ET-1 level,which was negative correlated with cerebral,renal,pancreatic,ear and toe microcirculation blood perfusion,was significantly increased in 5-to 18-week-old SHRs(P<0.05 or P<0.01).SHRs exhibited significant increased plasma MDA(at 8,13 weeks),IL-6(at 5 to 13 weeks)and significant reduced SOD activity(at 5 to 18 weeks),which is positive correlated with microcirculation blood perfusion of all organs.In addition,the expression of Claudin in kidney was decreased in 5-,13-and 18-week-old SHRs compared with WKYs,the expression of Claudin in 8-week-old SHRs was higher than that in 5-week-old SHRs,and the trend of Occludin and Claudin level were consistent,the expression of ZO-1 in SHRs was significantly decreased at 5 to 18 weeks(P<0.05 or P<0.01).Conclusions:SHRs exhibited decreased NO synthase,abnormal increased NO synthesis substrate and constriction factor of microvascular endothelial cell,activated inflammatory response,imbalanced oxidative stress and reduced tight junction protein levels,and microvascular endothelial cell were impaired.And systolic dysfunction and oxidative stress may be involved in microcirculatory dysfunction of SHRs. |
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