Abstract. Locally generated angiotensin II (AngII) may be involved in the pathogenic mechanisms of chronic renal diseases. Renal expression of AngII and other components of the renin-angiotensin system (RAS) were analyzed by immunohistochemistry and Western blot in a model of chronic progressive nephropathy induced by inhibition of nitric oxide synthesis. Renal injury was evaluated by histology and albumin excretion. Systemic RAS status was evaluated through plasma renin activity (PRA) and plasma AngII concentration. In addition, the effects of enalapril, losartan, and mycophenolate mofetil (MMF) on AngII expression in animals with chronic renal disease was also analyzed. Plasma renin activity and plasma AngII were not different between rats with nephropathy and controls (2.08 Ϯ 0.7 versus 2.03 Ϯ 0.5 ng/ml/h and 94.3 Ϯ 18 versus 78.9 Ϯ 16 fmol/ml, respectively). However, rats with chronic progressive nephropathy showed augmented renal content of angiotensinogen protein (13.5 Ϯ 3.5 versus 2.2 Ϯ 0.4 pixels in control rats; P Ͻ 0.05), enhanced expression of cathepsin D-a renin-like enzyme-in cortical collecting tubules (103.5 Ϯ 27.0 versus 66.2 Ϯ 3.6 cells/mm 2 in controls; P Ͻ 0.01), and increased expression of AT 1 receptor in interstitium (54.7 Ϯ 7.8 versus 1.3 Ϯ 0

The procedure using SICAC seemed to be feasible, effective, and safe resulting in a better control of BP, a short-term increase in estimated glomerular filtration rate, and reduced albuminuria. Although encouraging, our data are preliminary and need to be validated in the long term.

Graciano ML, Nishiyama A, Jackson K, Seth DM, Ortiz RM, Prieto-Carrasquero MC, Kobori H, Navar LG. Purinergic receptors contribute to early mesangial cell transformation and renal vessel hypertrophy during angiotensin II-induced hypertension. Am J Physiol Renal Physiol 294: F161-F169, 2008. First published November 7, 2007 doi:10.1152/ajprenal.00281.2007.-Chronic ANG II infusions lead to increases in intrarenal ANG II levels, hypertension, and tissue injury. Increased blood pressure also elicits increases in renal interstitial fluid (RIF) ATP concentrations that stimulate cell proliferation. We evaluated the contribution of purinergic receptor activation to ANG II-induced renal injury in rats by treating with clopidogrel, a P2Y12 receptor blocker, or with PPADS, a nonselective P2 receptor blocker. ␣-Actin expression in mesangial cells, afferent arteriolar wall thickness (AAWT), cortical cell proliferation, and macrophage infiltration were used as early markers of renal injury. Clopidogrel and PPADS did not alter blood pressure, renin or kidney ANG II content. ␣-Actin expression increased from control of 0.6 Ϯ 0.4% of mesangial area to 6.3 Ϯ 1.9% in ANG II-infused rats and this response was prevented by clopidogrel (0.4 Ϯ 0.2%) and PPADS. The increase in AAWT from 4.7 Ϯ 0.1 to 6.0 Ϯ 0.1 mm in ANG II rats was also prevented by clopidogrel (4.8 Ϯ 0.1 mm) and PPADS. ANG II infusion led to interstitial macrophage infiltration (105 Ϯ 16 vs. 62 Ϯ 4 cell/mm 2 ) and tubular proliferation (71 Ϯ 15 vs. 20 Ϯ 4 cell/mm 2 ) and these effects were prevented by clopidogrel (52 Ϯ 4 and 36 Ϯ 3 cell/mm 2 ) and PPADS. RIF ATP levels were higher in ANG IIinfused rats than in control rats (11.8 Ϯ 1.9 vs. 5.6 Ϯ 0.6 nmol/l, P Ͻ 0.05). The results suggest that activation of vascular and glomerular purinergic P2 receptors may contribute to the mesangial cell transformation, renal inflammation, and vascular hypertrophy observed in ANG II-dependent hypertension. extracellular ATP; renal inflammation; vascular hypertrophy ANG II-DEPENDENT HYPERTENSION is characterized by increases in intrarenal ANG II content and renal functional impairment with variable degrees of injury to several organs and tissues, including heart, kidney, and blood vessels (7,16,23,25,31,38,42,47,50). The ANG II-associated tissue injury occurs more consistently in a setting of elevated arterial pressure suggesting that factors existing in hypertensive, but not normotensive, conditions may be contributing to the damage observed during hypertension caused by chronic ANG II infusions. While mechanical forces caused by the elevated arterial pressures directly cause baromechanical trauma (1), elevated arterial pressure may independently activate paracrine systems that contribute to the ANG II-mediated vascular and tissue injury (38, 47). Various proliferative agents are capable of inducing vascular hypertrophy, mesangial activation, or cortical renal injury (38). These independent factors, directly stimulated by the elevated arterial pressure, may synergize with the eleva...

Graciano ML, Mouton CR, Patterson ME, Seth DM, Mullins JJ, Mitchell KD. Renal vascular and tubulointerstitial inflammation and proliferation in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension. Am J Physiol Renal Physiol 292: F1858 -F1866, 2007. First published March 6, 2007;doi:10.1152/ajprenal.00469.2006.-Transgenic rats with inducible ANG II-dependent malignant hypertension [TGR(Cyp1a1Ren2)] were generated by inserting the mouse Ren2 renin gene into the genome of the rat. The present study was performed to assess renal morphological changes occurring during the development of ANG IIdependent malignant hypertension in these rats. Male Cyp1a1-Ren2 rats (n ϭ 10) were fed normal rat food containing indole-3-carbinol (I3C; 0.3%) for 10 days to induce malignant hypertension. Rats induced with I3C had higher mean arterial pressures (173 Ϯ 9 vs. 112 Ϯ 11 mmHg, P Ͻ 0.01) than noninduced normotensive rats (n ϭ 9). Glomerular damage was evaluated by determination of the glomerulosclerosis index (GSI) in tissue sections stained with periodic acid-Schiff. Kidneys of hypertensive rats had a higher GSI than normotensive rats (21.3 Ϯ 5.6 vs. 3.5 Ϯ 1.31 units). Quantitative analysis of macrophage ED-1-positive cells and proliferating cell nuclear antigen using immunohistochemistry demonstrated increased macrophage numbers in the renal interstitium (106.4 Ϯ 11.4 vs. 58.7 Ϯ 5.0 cells/mm 2 ) and increased proliferating cell number in cortical tubules (37.8 Ϯ 5.7 vs. 24.2 Ϯ 2.1 cells/mm 2 ), renal cortical vessels (2.2 Ϯ 0.5 vs. 0.13 Ϯ 0.07 cells/vessel), and the cortical interstitium (33.6 Ϯ 5.7 vs. 4.2 Ϯ 1.4 cells/mm 2 ) of hypertensive rat kidneys. These findings demonstrate that the renal pathological changes that occur during the development of malignant hypertension in Cyp1a1-Ren2 rats are characterized by inflammation and cellular proliferation in cortical vessels and tubulointerstitium. kidney; glomerulosclerosis; renal injury; immunohistochemistry; renin-angiotensin system; renal pathology; peptide hormones TRANSGENIC RATS WITH INDUCIBLE activation of extrarenal renin gene expression [TGR(Cyp1a1Ren2)] were generated using a renin transgene under the transcriptional control of the cytochrome P-450 (Cyp1a1) promoter (23). This transgenic rat line was created by inserting a mouse Ren2 renin gene, fused to an 11.5-kb fragment of the Cyp1a1 promoter, into the genome of the Fischer 344 rat (23). Cyp1a1, which catalyzes the oxidation of a wide range of endogenous lipophilic compounds and xenobiotics (7, 10, 43), is not constitutively expressed but is highly inducible on exposure to various aryl hydrocarbons such as indole-3-carbinol (I3C) (7,10,14,21,26,33,43). Induction of Cyp1a1 is mediated by the aryl hydrocarbon receptor, which is a basic helix-loop-helix-transcription factor that binds to specific DNA elements in the Cyp1a1 promoter (7, 13, 43). Rats transgenic for the Cyp1a1-Ren2 construct do not constitutively express the Ren2 renin gene. Rather, the Ren2 gene is expressed, primarily i...

The contribution of elevated aldosterone to the pathogenesis of malignant, ANG II-dependent hypertension remains uncertain. Therefore, we examined whether chronic mineralocorticoid receptor blockade attenuates the development of malignant hypertension in transgenic rats (TGRs) with inducible expression of the Ren2 gene [TGR(Cyp1a1Ren2)]. Systolic blood pressure (SBP) was measured by radiotelemetry in male TGRs in three groups: 1) control (n = 9), 2) hypertensives (HT; n = 8), and 3) hypertensives + spironolactone (11 mg.kg(-1).day(-1) sc; HTS; n = 8). Malignant hypertension was induced with dietary indole-3-carbinol (0.3%) for 10 days. Metabolic measurements were taken at the beginning of the study and at days 2 and 9. HT exhibited elevated SBP (125 +/- 3 vs. 187 +/- 5 mmHg), plasma renin activity (5 +/- 1 vs. 29 +/- 10 ng ANG I.ml(-1).h(-1)), plasma ANG II (175 +/- 39 vs. 611 +/- 74 fmol/ml), and plasma aldosterone (0.31 +/- 0.04 vs. 5.42 +/- 1.02 nmol/l). Urinary aldosterone excretion increased 5.5-fold by day 2 and an additional 90% by day 9. HT was associated with a 1.8-fold increase in proteinuria by day 9 that was alleviated by treatment with spironolactone (25 +/- 5 vs. 13 +/- 3 mg/day), suggesting that aldosterone contributes to the renal damage observed in malignant hypertension. Urinary Na+ excretion was decreased 76% on day 2, despite a sixfold increase in urinary aldosterone excretion. Decrease in urinary Na+ excretion on day 2 in HT suggests that Na+ reabsorption was increased in response to the increase in aldosterone; however, the lack of a change in SBP between HT and HTS suggests that mechanisms independent of aldosterone stimulation make a greater contribution to the maintenance of elevated arterial pressure in malignant hypertension in Cyp1a1-Ren2 transgenic rats.