Dexamethasone‐induced diuresis is associated with inhibition of the renin–angiotensin–aldosterone system in rats

Figures

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  Figure 1. Effects of water restriction (WR) on renin–angiotensin–aldosterone system (RAAS). (A) The effect of WR on plasma ANG II levels; *p < 0.05 compared with 0 hours of WR; n = 6 in each group; (B) the effect of WR on plasma aldosterone levels; *p < 0.05 compared with 0 hours of WR. ANG II = angiotensin II; RAAS = renin–angiotensin–aldosterone system; WR = water restriction.

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  Figure 2. Dose‐dependent effects of Dex on RAAS in rats with WR. (A) Effects of increasing doses of Dex on plasma ANG II levels; *p < 0.05 compared with vehicle control; n = 10 in each group; (B) effects of increasing doses of Dex on plasma aldosterone levels; *p < 0.05 compared with the vehicle control; (C) effects of increasing doses of Dex on urine output during the pretreatment period; *p < 0.05 compared with the vehicle control. ANG II = angiotensin II; Dex = dexamethasone; RAAS = renin–angiotensin–aldosterone system; WR = water restriction.

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  Figure 3. Time‐dependent effects of Dex on RAAS in rats with WR. (A) Effects of increasing Dex pretreatment time on plasma ANG II levels; n = 9 in each group; (B) effects of increasing Dex pretreatment times on plasma aldosterone levels; *p < 0.05 compared with control (vehicle) group; (C) effects of increasing Dex pretreatment times on urine output during the pretreatment period; *p < 0.05 compared with the control. ANG II = angiotensin II; Dex = dexamethasone; RAAS = renin–angiotensin–aldosterone system; WR = water restriction.

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  Figure 4. Reversal of the effects of Dex on RAAS by the inhibitor RU486 in rats with WR. (A) RU486 reversed the effects of Dex on plasma ANG II expression in the WR rats; *p < 0.05 compared with the vehicle control; n = 9 in each group; (B) RU486 reversed the effects of Dex on plasma aldosterone expression in WR rats; *p < 0.05 compared with the vehicle control; (C) RU486 reversed the effects of Dex on urine output in the WR rats; *p < 0.05 compared with the vehicle control. ANG II = angiotensin II; Dex = dexamethasone; WR = water restriction.

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  Figure 5. Effect of Dex on RAAS in rats with chronic heart failure. (A) Effect of Dex on plasma ANG II levels; n = 5 in each group; (B) effect of Dex on plasma aldosterone levels; (C) effect of Dex on urine output during pretreatment period; *p < 0.05 compared with HF‐C and ST‐C groups. ANG II = angiotensin II; CHF = chronic heart failure; Dex = dexamethasone; HF‐C = rats with HF treated with vehicle; HF‐I = rats with HF treated with Dex; RAAS = renin–angiotensin–aldosterone system; ST‐C = standard control (sham operated rats); WR = water restriction.

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  Figure 6. Effect of Dex on RAAS in rats with CHF during acute volume expansion tests. (A) Effect of Dex on plasma ANG II levels; n = 6 in ST‐C and HF‐C groups and n = 7 in the HF‐I group; (B) effect of Dex on plasma aldosterone levels; (C) effect of Dex on urine output during the pretreatment and volume expansion period; *p < 0.05 between the two groups. ANG II = angiotensin II; CHF = chronic heart failure; Dex = dexamethasone; HF‐C = rats with HF treated with vehicle; HF‐I = rats with HF treated with Dex; RAAS = renin–angiotensin–aldosterone system; ST‐C = standard control (sham operated rats).