| Objective:The kidney specific voltage gated chloride channel(CLC-K)is mainly distributed in the kidney and plays an important role in regulating the excretion of Cl~-.CLC-K2 is mainly distributed in the thick ascending limb of the loop of Henle,Distal convoluted tubule,the collecting tube and the intercalated cells in connecting the tubules,which can affect the regulation of blood pressure.The incidence of essential hypertension increased in the population with increased CLC-K2 activity.After the intervention of angiotensin II or high salt,the blood pressure increased,and the expression level of CLC-K2 mRNA increased.While the blood pressure of mice(rats)decreased after knocking out of CLC-K2 gene or inhibiting activity of CLC-K2 by drugs.Hydrochlorothiazide is a kind of antihypertensive drug which is widely used all over the world.The mechanism of antihypertension is not completely clear,and there is a significant difference in the reactivity of hypotensive therapy for hydrochlorothiazide in different hypertensive patients.The study of the mechanism of hydrochlorothiazide plays an important role in the selectionchoice of the kinds of antihypertensive drugs correctly.The aim of this study is to explore the effect of hydrochlorothiazide on the expression level of CLC-K2 gene in the kidney of spontaneously hypertensive rats,so as to provide a theoretical basis for the mechanism of hydrochlorothiazide.Methods:Thirty healthy male SHR rats of clean grade with 8 weeks old and body weights 230-258g were included.Two weeks after adaptation,SHR rats were randomly divided into 2 groups according to the proportion of 2:1.Twenty rats were set up as experimental group,and 10 rats were set as control group.Rats in experimental group were given hydrochlorothiazide for 10mg/kg/day at 19:00 every day and rats in control group were given equal dose of distilled water at the same time for 10 weeks.The weight,urine volume and systolic blood pressure(SBP)of the rats in 2 groups were recorded before and after the treatment.After intraperitoneal injection of 10%chloral hydrate,the kidneys of all rats were taken out,and blood was separated from the abdominal aorta.Then the levels of CLC-K2 and Ang II in the kidneys were measured by Real Time PCR and ELISA respectively.If the CLC-K2 mRNA expression level of rats in experimental group and control group was different,then according to the amplitude of blood pressure reduction,rats in the experimental group were further divided into group A,B,C and D on the basis of quartile method.Results:1.Independent sample t test showed that there was no significant difference in body weight,urine volume and systolic blood pressure between the experimental group and the control group before the treatment(P>0.05).2.Paired t test showed that there was no significant difference in systolic pressure and urine volume in the control group in comparison with that before treatment(P>0.05).The weight of the experimental group and the control group increased in comparison with that before treatment,the difference was statistically significant(P<0.05).The systolic blood pressure of rats in the experimental group was lower than that before experiment,and the difference was statistically significant(P<0.05).Independent sample t test showed that the difference of weight between the experimental group and the control group was not statistically significant(P>0.05).3.Independent sample t test showed that there was no significant difference in serum AngII concentration between the rats in experimental group and control group(P>0.05).4.Independent sample t test showed that the CLC-K2 level of rats in the experimental group is higher than that in the control group(1.77 fold)(P<0.05).5.ANOVA showed that the four groups of A,B,C and D had different reactivity to hypotensive effect of hydrochlorothiazide,differences are statistically significant(P<0.01).There was no significant difference in the expression level of CLC-K2 mRNA between the four groups(P>0.05).Conclusions:1.Long term administration of hydrochlorothiazide could decrease blood pressure of SHR rats.2.The long-term antihypertensive mechanism of hydrochlorothiazide is not related to the reduction of circulating blood volume.3.The long-term effect of hydrochlorothiazide has no effect on the level of AngII in serum.4.The expression of renal CLC-K2 can be improved by hydrochlorothia-zide5.There are individual differences in hypotensive effect of hydrochlorothiazide,which is not related to the level of CLC-K2 mRNA expression. |
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