Effect Of High Potassium Diet On Blood Pressure In Spontaneously Hypertensive Rats

Objective:To explore the effect of high potassium intake on blood pressure in spontaneously hypertensive rats.Methods:SHR and WKY rats were kept on high potassium diet for one week.The change of the SHR and WKY systolic pressure were measured by tail cuff technique before and after high potassium diet.Used Western blot to detected the effect of dietary potassium intake on tNCC,pNCC,Kir4.1,WNK4,SPAK,ENaC and ROMK protein expression in the kidney of WKY and SHR.And the expression of Kir4.1 were also observed with IHC.Changes in electrolytes(Na~+?K~+)in urine and blood of SHR and WKY rats on high potassium were evaluated by automatic biochemical analyzer.Results:(1)The systolic blood pressure were higher in SHR than in WKY rats with normal diet.Potassium supplementation reduced systolic blood pressure in SHR from the fifth days but not happened in WKY rats.It showed that compared with WKY rats,high potassium could significantly reduce the blood pressure of SHR.(2)The tNCC,pNCC expression of the kidney in the SHR were increased compared with the WKY and high potassium diet displayed a significant decrease on it.However,the decline level in SHR was higher than that of WKY rats.It means potassium intake and blood pressure levels involves NCC regulation in the DCT.(3)The protein expression of WNK4,SPAK in SHR were higher than in WKY rats.High potassium diet decreased the levels of them.That means the blood pressure is decreased in response to high potassium diet due to lower WNK4 and SPAK activity.(4)The expression of Kir4.1 in the kidney of SHR was stronger than in WKY rats with normal diet.High potassium intake decreased more expression of Kir4.1 in comparison with control group,this suggests dietary potassium intake induced regulation of the blood pressure is the result of the inhibition of Kir4.1.(5)IHC results showed that compared with WKY group,high potassium diet significantly reduced the average optical density of Kir4.1 potassium channel protein in the kidney of SHR rats,which showed that Kir4.1 potassium channel participated in the regulation of high potassium diet on blood pressure of SHR rats.(6)Compared with WKY group,the urinary sodium excretion of SHR rats increased significantly after high potassium diet,indicating that high potassium diet can increase the urinary sodium excretion.Moreover,high potassium diet significantly increased urinary potassium excretion in WKY and SHR rats.(7)High potassium diet had no significant effect on the expression of?-ENaC in each group,but increased?-ENaC protein,and also increased the expression of ROMK which responsible for potassium secretion.It is suggested that?-ENaC and ROMK are related to the changes of urinary sodium and potassium excretion caused by high potassium diet.Conclusion:(1)High potassium can reduce blood pressure in the SHR.(2)High potassium diet may be through inhibiting Kir4.1-WNK4-SPAK-NCC signaling pathway and then increasing urinary Na~+excretion to regulate the blood pressure in SHR.