Effect And Mechanism Of High Salt Diet On Arterial Blood Pressure In SLC14?1 Gene Depletion Mice

Background:The SLC14?1 gene encodes UTB protein which facilities urea transport across the membrance.UTB is mainly expressed in brain,kidney,heart,and testis.Dahl S rats were given a high-salt diet,microarray results showed that the expression of SLC14?1 gene in choroid plexus was significantly downregulated.The previous study found that: SLC14?1 gene was expressed in choroid plexus of Dahl S rats;After 2w high salt diet,the expression of SLC14?1 gene was significantly downregulated;blood pressure and cerebrospinal fluid sodium concentration were significantly increased;suggesting that SLC14?1 gene involved in the occurrence of salt-sensitive hypertension;but the mechanism is not yet clear.Therefore,the objective of this study is to observe the changes of mean arterial blood pressure and cerebrospinal fluid sodium concentration in mice with SLC14?1 gene depletion mice after high salt diet4 w and analyze the mechanism.Objective:To investigate the effect of high salt diet on arterial blood pressure in SLC14?1gene depletion mice and analyze its mechanism.Methods and Results:1.Obain the SLC14?1 gene depletion mice Heterozygote mice were mated,and then UTB expression were decteced by genome DNA PCR.The results of DNA PCR shows that a base fragment band in400 bp of wild mice;250bp and 400 bp of heterozygote mice;and 250 bp of depletion mice.2.The effect of high salt diet on the mean arterial blood pressure in SLC14?1 gene depletion mice The mean arterial blood pressure of mice was measured by noninvasive blood pressure monitor.The results showed that the mean arterial blood pressure increased significantly in the SLC14?1 gene depletion mice on high salt diet(P<0.05),but the mean arterial blood pressure of wild type mice did not show significant difference after giving high salt diet for 4w.It suggested that the deficiency of SLC14?1 gene could increase the mean arterial blood pressure in mice on high salt diet.3.The effect of high salt diet on urine sodium in SLC14?1 gene depletion mice Sodium ion kit was used to detect the excretion of urine sodium in mice.It was found that the concentration of sodium in urine of SLC14?1 gene depletion mice fed on high salt diet was significantly higher than that of wild type mice.4.The effect of high salt diet on serum Aldosterone in SLC14?1 gene depletion mice Sodium ion kit was used to detect the concentration of serum aldosterone in mice.The concentration of serum aldosterone was increased significantly in SLC14?1 gene depletion mice fed on high salt diet.5.Expression of SLC14?1 gene and protein in the choroid plexus of brain tissue RT-PCR,Western-blot and immunohistochemistry were used to detect the expression of SLC14?1 m RNA and UTB protein in choroid plexus of mice.The results showed that SLC14?1 m RNA and UTB protein located on the epithelial cells membrane of choroid plexus in mice.6.Effect of SLC14?1 gene deficiency on the urea concentration of serum and cerebrospinal fluid in mice The results of urea nitrogen showed that SLC14?1 gene deficiency increased the urea concentration of the serum and cerebrospinal fluid in mice significantly.It is confirmed that UTB mediates the transcellular membrane transport of urea,and the loss of UTB causes the barrier in urea transport,which leads to a significant increase in the content of urea in the serum and cerebrospinal fluid.7.Effect of high salt diet on Na+ concentration of serum and cerebrospinal fluid in SLC14?1 gene depletion miceThe results showed that the Na+ concentration in serum and cerebrospinal fluid of SLC14?1 gene depletion mice was increased significantly(P<0.05)on high salt diet.The above results showed that high salt diet increased Na+ concentration of serum in SLC14?1 gene depletion mice,which resulted in an increased sodium transportation into cerebrospinal fluid.8.Effect of high salt diet on the expression of ENa C-? in choroid plexus of the SLC14?1 gene depletion mice RT-PCR,Western-blot and immunohistochemistry were used to detect the expression of ENa C-? in choroid plexus of mice.Results showed that expression of ENa C-? protein was increased significantly in SLC14?1 gene depletion mice fed on high salt diet(P<0.05).Immunohistochemistry results showed that expression of ENa C-? protein located on the epithelial cells membrane of choroid plexus.The results showed that high salt diet increased the expression of ENa C-? in the choroid plexus of SLC14?1 gene depletion mice,leading to transporting sodium into cerebrospinal fluid.9.Effect of high salt diet on MR of the choroid plexus in SLC14?1 gene depletion mice The results of RT-PCR showed that the MR level in the choroid plexus of SLC14?1 gene depletion mice fed on high salt diet was significantly higher than that in the wild type mice.10.Effect of high salt diet on the expression and activity of ?1-Na+-K+-ATPase in choroid plexus of SLC14?1 gene depletion mice RT-PCR,Western-blot and immunohistochemistry were used to detect the expression of ?1-Na+-K+-ATPase in choroid plexus of mice.Results showed that expression of ?1-Na+-K+-ATPase protein was increased significantly in SLC14?1gene depletion mice fed on high salt diet(P<0.05).Immunohistochemistry results showed that expression of ?1-Na+-K+-ATPase protein located on the epithelial cells membrane of choroid plexus.The results showed that the activity of ?1-Na+-K+-ATPase was increased significantly in SLC14?1 gene depletion mice fed on high salt diet(P<0.05).The above results showed that high salt diet increased the expression and activity of ?1-Na+-K+-ATPase in choroid plexus of SLC14?1 gene depletion mice,leading to transporting sodium into cerebrospinal fluid.11.Effect of high salt diet on serum Ang II in SLC14?1 gene depletion mice The increase of Ang II concentration in the serum was induced by the increase of Na+ concentration in cerebrospinal fluid.Serum Ang II was detected by kits in mice,and found that high salt diet increased the concentration of Ang II in serum of SLC14?1 gene depletion mice significantly(P<0.05),but did not affect the change of serum Ang II in wild type mice.It showed that the high salt diet could increase the concentration of Ang II in the serum of SLC14?1 gene depletion mice,and increase blood pressure.Conclusion:The expression and activity of ENa C-? and ?1-Na+-K+-ATPase of choroid plexus were increased in SLC14?1 gene depletion mice fed on 4w high salt diet;the Na+concentration of cerebrospinal fluid(CSF[Na+])was increased;the increased CSF[Na+] raised serum Ang II concentration which could increase blood pressure.