The Relationship Between Carotid-femoral Pulse Wave Velocity And Type I Collagen In Rats With Chronic Renal Failure

Objective:Cardiovascular disease (CVD) is the main complication and the leadingcause of death in patients with chronic kidney disease (CKD), especially inpatients with end-stage renal disease (ESRD), accounting for more than1/2ofthe number of the deaths. CKD patients is the high risk population of CVD.Both of them promote each other and influence each other. Cardiovascularanomalies have occurred even at the early stage of CKD and exacerbate withthe progression of the disease. And the impairment of elasticity function ofblood vessel is one of the early important signs of cardiovascular disease.Present studies have confirmed that extracellular matrix, which is mainlycomposed of type I collagen, is increased in vessels in patients with chronicrenal failure. So in this study, a rat model with chronic renal failure was usedto create uremia environment, and we examine the carotid-femoral pulse wavevelocity (PWV) and type I collagen expression to demonstrate the relationshipbetween elasticity function of aorta and type I collagen expression in thoracicaorta.Methods：Experimen-control and self-control were used in the Present study.1Experiment subjects:1.1Clean, healthy, male Wistar rats;1.2The body mass of170-230g, a total of50;1.3After1weeks of adaptation feeding in barrier environment of the animalcenter in the Fourth Hospital of Hebei Medical University, eliminate the ratswith body mass too large or too small. The rest rats were randomly dividedinto2groups (sham group and chronic kidney failure group), with18rats ineach group. 2The experimental methods:2.15/6nephrectomy method (Platt method) was used to build the rat model ofchronic renal failure, the control group underwent sham operation.2.2After12weeks, we sacrificed all rats at three times (every other week after12weeks’ feeding), using the RM624BD multi-channel physiological signalacquisition system and analysis software to examine carotid-femoral PWV toassess the elasticity function of aorta in rats. At the same time, collect bloodsamples the heart and detected serum biochemical parameters of the bloodcreatinine, urea nitrogen, calcium and phosphorus concentration (see Table1).2.3The descending thoracic aorta and kidney specimens were collected andsome were fixed in10%formalin fixed and the residual parts were stored in-80℃refrigerator, used for immunohistochemical staining and HE staining toobserve the change of intima-media, the expression of type I collagen andpathological changes of the kidney.3Statistical methods: Analyses were performed using SPSS13.0softwarepackage. The measurement data were described in (x±S). One-way analysisof variance was used to compare among groups. After testing for normaldistribution, t test or nonparametric test (NPar) was used where appropriate.Relationships between variables were tested by Spearman correlation analysis.Statistical significance was de fined as P<0.05.Results：1The build of chronic renal failure rats1.1The serological parameters showed that: Scr, BUN serum level ofexperimental group was markedly higher than that of the control group (P<0.01). While serum Ca in the experimental group was significantly lower thanthe control group (P<0.01). There was no significant difference between theexperimental group and the control group in P level (P>0.05).1.2The HE staining is consistent with the changes of chronic renal failure.2. Comparison of pulse wave velocity between the two groupsPWV was higher in chronic renal failure group (11.957±2.924) m/s thansham group PWV(4.649±0.479) m/s, the differences between the two groups was statistically significant (P<0.05).3collagen expression in thoracic aorta of the two groupsThe expression of typeⅠcollagen was higher in chronic renal failuregroup (52.989±1.927)/HP than sham group (30.044±1.206)/HP, there wasstatistically significant difference between two groups (P <0.05).4Relations between type I collagen and PWV in experimental groupsIn experimental groups, PWV (11.957±2.924) m/s was correlated withtype Ⅰcollagen (52.989±1.927)/HP,(P <0.05, r=0.565).5The relationship between PWV and Scr, BUN, Ca, P in the experimentalgroupsIn experimental groups, PWV (12.089±2.884) m/s was positivelycorrelated with Scr (60±15.656) umol/L (P <0.05, r=0.491); while there wasno relationship between BUN (10.194±2.474) mmol/L, Ca (1.955±0.427)mmol/L, P (2.094±0.338) mmol/L and PWV (12.089±2.884) m/s (P>0.05),namely BUN, Ca, P had no correlation with PWV.Conclusions:1In rats with chronic renal failure, the stiffness of the aorta is increasedand elastic function is decreased.2In chronic renal failure rats, the expression of type Ⅰ collagen inaortic is increased while there were no significant changes in the sham group.3PWV of thoracic aorta of rats with chronic renal failure was increased,that is to say the stiffness of aorta was increased and the elastic function wasreduced. This may be associated with the uremia environment and theincreased in type Ⅰcollagen expression.