Abstract-The renin-angiotensin system plays an important role in renal development. However, it is unknown whether reduction in angiotensin II effects during the nephrogenic period leads to different renal alterations in males and females during the adult age. The aim of this study was to evaluate whether the role of angiotensin II on renal development is sex dependent and whether there are sex differences in blood pressure, renal hemodynamics, and severity of renal damage during adult life when nephrogenesis is altered by blocking angiotensin II effects. Newborn Sprague-Dawley rats were treated with an angiotensin II type 1 receptor antagonist (L-158.809; 7 mg/kg per day) during the first 2 weeks of life. At 3 months of age, changes in blood pressure, albuminuria, and renal hemodynamics were assessed, and stereological and histopathologic studies were performed. Blood pressure increased (127Ϯ0.5 versus 115Ϯ0.7 mm Hg in control rats; PϽ0.05) and nephron number decreased (37%; PϽ0.05) similarly in treated males and females. However, only males had an elevation in albuminuria (5.92Ϯ1.65 versus 0.33Ϯ0.09 mg per day in control rats; PϽ0.05), a fall in glomerular filtration rate (12.6%; PϽ0.05), and a significant decrease in papillary volume (42%; PϽ0.05). Mean glomerular volume, glomerulosclerosis, arteriolar hypertrophy, and tubulointerstitial damage in cortex and medulla were also higher (PϽ0.05) in angiotensin II type 1 receptor antagonist-treated males than in treated females. The results of this study suggest that females seem to be more protected than males to the renal consequences of reducing angiotensin II effects during renal development.

Abstract-We have demonstrated that the reduction of angiotensin II effects during the nephrogenic period reduces the nephron number and induces the development of hypertension. The hypotheses examined are that this reduction of angiotensin effects leads to the development of an age-dependent sodium sensitive hypertension and that the hypertension is angiotensin II dependent. Newborn rats were treated with an angiotensin II type 1 receptor antagonist during the first 2 weeks of age. At 3 to 4 and 11 to 12 months of age, changes in systolic blood pressure, proteinuria, and renal function in response to a prolonged high sodium intake were examined. The basal blood pressure response to the administration of the angiotensin II receptor antagonist was also evaluated at both ages. Basal blood pressure was similarly elevated (PϽ0.05) in male and female treated rats, and the increment was age dependent. High sodium intake only elicited a blood pressure elevation (136Ϯ1 to 154Ϯ3 mm Hg; PϽ0.05) and a decrease in glomerular filtration rate (28%; PϽ0.05) at 11 to 12 months in treated rats. Blockade of angiotensin II receptors during renal development induced an increase (PϽ0.05) in proteinuria that was age and sex dependent, but high sodium intake only induced an elevation in proteinuria in the younger rats (50%; PϽ0.05). Hypertension was maintained by angiotensin II at both ages because blood pressure decreased to normal levels after treatment with an angiotensin II type 1 receptor antagonist. This study shows that the reduction of angiotensin II effects during the nephrogenic period modifies renal function and induces the development of an angiotensin II-dependent hypertension that becomes sodium sensitive during aging. T he importance of nephron number in the development of hypertension and renal dysfunction is supported by experimental and clinical studies [1][2][3][4][5][6][7][8][9] demonstrating that the alteration of nephrogenesis regulation leads to significant changes in arterial pressure and renal function during the adulthood. These effects of the reduction in nephron number during renal development seem to be more significant than those elicited by a decrease in nephron number later in life. 2 One mechanism that is involved in the regulation of nephrogenesis is the renin-angiotensin system (RAS). The role of RAS has been confirmed in previous studies of our group demonstrating that the blockade of the angiotensin II (Ang II) type 1 (AT 1 ) receptors during the late nephrogenic period reduces nephron number by 37%, induces the development of hypertension, and elicits important renal changes that are greater in male than in female rats. 7,8 An age-and sexdependent increment in proteinuria is observed in rats when the effects of Ang II via the AT 1 receptor are reduced during the nephrogenic period. 7,8 These rats also have a decrease in renal functional reserve, because the response to an increment in plasma amino acid levels is deteriorated, and their renal excretory ability to eliminate an acute sodium load is im...

This study was designed to test the hypothesis that blockade of angiotensin II effects during renal development accelerates the aging-related changes in renal hemodynamics and proteinuria, and that these changes are sex dependent. It has also been examined whether the deterioration of urinary concentrating ability elicited by angiotensin II blockade is sex and/or aging dependent. Newborn Sprague-Dawley rats were treated with vehicle or an AT(1) angiotensin II receptor antagonist (ARA) during the first 14 postnatal days. Blood pressure, glomerular filtration rate, proteinuria, and urinary concentrating ability in response to dehydration were examined in conscious rats at 3 and 11 mo of age. ARA treatment elicited a similar increment in blood pressure in males and females that was greater (P < 0.05) at 11 than at 3 mo of age. Glomerular filtration rate only decreased (P < 0.05) in 11-mo-old male ARA-treated rats (0.59 +/- 0.07 vs. 0.80 +/- 0.07 ml.min(-1).g(-1) in control group). At 3 mo of age, proteinuria increased in male (107%) but not in female ARA-treated rats. However, at 11 mo of age, proteinuria increased in both sexes, but the increment was greater (P < 0.05) in male (244%) than in female (138%) ARA-treated rats. Renal ability to concentrate urine in response to prolonged water dehydration was only reduced in ARA-treated males. The reduction of urinary concentrating ability was accentuated by aging. Therefore, we conclude that blockade of angiotensin II effects during renal development elicits an important deterioration of cortical and medullary function that is sex and aging dependent.

Numerous studies have demonstrated that angiotensin II (ANG II) is involved in hypertension and renal changes occurring as a consequence of an adverse event during renal development. However, it was unknown whether this involvement is sex and age dependent. This study examines whether the increments in arterial pressure (AP) and in the renal sensitivity to ANG II are sex and age dependent in rats with altered renal development. It also evaluates whether the ANG II effects are accompanied by increments in AT(1) receptors and oxidative stress. Experiments were performed in 3- to 4- and 10- to 11-mo-old rats treated with vehicle or an AT(1) receptor antagonist (ARAnp) during the nephrogenic period. ARAnp-treated rats were hypertensive, but an age-dependent rise in AP was only found in males. Three days of treatment with candesartan (7 mg·kg(-1)·day(-1)) led to a fall of AP that was greater (P < 0.05) in male than in female 10- to 11-mo-old ARAnp-treated rats. Oxidated proteins were elevated (P < 0.05), and the decrease in AP elicited by candesartan was reduced (P < 0.05) when these rats are also treated with tempol (18 mg·kg(-1)·day(-1)). Hypertension was not maintained by an elevation of AT(1) receptors in kidneys and mesenteric arteries. The acute renal hemodynamic response to ANG II (30 ng·kg(-1)·min(-1)) was similarly enhanced (P < 0.05) in both sexes of ARAnp-treated rats at 3-4 but not at 10-11 mo of age. Our results suggest that an adverse event during the nephrogenic period induces an ANG II-dependent increment in AP that is aggravated only in males during aging and that oxidative stress but not an increase in AT(1) receptor contributes to the rise in AP. This study also shows that the renal hemodynamic sensitivity to ANG II is transitorily enhanced in both sexes of rats with altered renal development.

Augmented intratubular angiotensin (ANG) II is a key determinant of enhanced distal Na reabsorption via activation of epithelial Na channels (ENaC) and other transporters, which leads to the development of high blood pressure (BP). In ANG II-induced hypertension, there is increased expression of the prorenin receptor (PRR) in the collecting duct (CD), which has been implicated in the stimulation of the sodium transporters and resultant hypertension. The impact of PRR deletion along the nephron on BP regulation and Na handling remains controversial. In the present study, we investigate the role of PRR in the regulation of renal function and BP by using a mouse model with specific deletion of PRR in the CD (PRR-KO). At basal conditions, PRR-KO mice had decreased renal function and lower systolic BP associated with higher fractional Na excretion and lower ANG II levels in urine. After 14 days of ANG II infusion (400 ng·kg·min), the increases in systolic BP and diastolic BP were mitigated in PRR-KO mice.PRR-KO mice had lower abundance of cleaved αENaC and γENaC, as well as lower ANG II and renin content in urine compared with wild-type mice. In isolated CD from PRR-KO mice, patch-clamp studies demonstrated that ANG II-dependent stimulation of ENaC activity was reduced because of fewer active channels and lower open probability. These data indicate that CD PRR contributes to renal function and BP responses during chronic ANG II infusion by enhancing renin activity, increasing ANG II, and activating ENaC in the distal nephron segments.