Nrf1 Knock-Down in the Hypothalamic Paraventricular Nucleus Alleviates Hypertension Through Intervention of Superoxide Production-Removal Balance and Mitochondrial Function

Oxidative stress in the hypothalamic paraventricular nucleus (PVN) contributes greatly to the development of hypertension. The recombinant nuclear respiratory factor 1 (Nrf1) regulates the transcription of several genes related to mitochondrial respiratory chain function or antioxidant expression, and thus may be involved in the pathogenesis of hypertension. Here we show that in the two-kidney, one-clip (2K1C) hypertensive rats the transcription level of Nrf1 was elevated comparing to the normotensive controls. Knocking down of Nrf1 in the PVN of 2K1C rats can significantly reduce their blood pressure and level of plasma norepinephrine (NE). Analysis revealed significant reduction of superoxide production level in both whole cell and mitochondria, along with up-regulation of superoxide dismutase 1 (Cu/Zn-SOD), NAD(P)H: quinone oxidoreductase 1 (NQO1), thioredoxin-dependent peroxiredoxin 3 (Prdx3), cytochrome c (Cyt-c) and glutathione synthesis rate-limiting enzyme (glutamyl-cysteine ligase catalytic subunit (Gclc) and modifier subunit (Gclm)), and down-regulation of cytochrome c oxidase subunit VI c (Cox6c) transcription after Nrf1 knock-down. In addition, the reduced ATP production and elevated mitochondrial membrane potential in the PVN of 2K1C rats were reinstated with Nrf1 knock-down, together with restored expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitochondrial transcription factor A (Tfam), coiled-coil myosin-like BCL2-interacting protein (Beclin1), and Mitofusin 1 (Mfn1), which are related to the mitochondrial biogenesis, fusion, and autophagy. Together, the results indicate that the PVN Nrf1 is associated with the development of 2K1C-induced hypertension, and Nrf1 knock-down in the PVN can alleviate hypertension through intervention of mitochondrial function and restorement of the production-removal balance of superoxide.

Ischemic nephropathy: more than a simple renal artery narrowing

Renal artery stenosis in elderly patients is mainly caused by atherosclerosis. The prevalence of this disorder in patients with chronic kidney diseases is reported to be 0.5% to 5.5%. However, because the patients with atherosclerotic renal artery disease are mostly asymptomatic, the true prevalence is expected to be higher. Renovascular hypertension and ischemic nephropathy are two main consequences of this disease, but it is difficult to determine in which patient the progress of stenosis may cause these syndromes. The big challenge in renal artery stenosis is how to manage the patients. In the past 70 years, it has been believed that simply maintaining of kidney perfusion by opening the stenosis could control blood pressure and preserve kidney function. Nowadays, the blood pressure can be controlled well by medical treatment without the need for revascularization; however, management of ischemic nephropathy remains a dilemma. With advancements in understanding the pathophysiology of changes in the parenchyma of the kidney after stenosis, it is now generally accepted that only a minority of patients with ischemic nephropathy will benefit from revascularization. Nonetheless, finding these patients is critical and need more randomized trials to show who mostly benefit from revascularization and when it may save the kidney.

Managing diabetic nephropathy

The earliest sign of DN is the development of microalbuminuria which is associated with a significant risk of both progressive renal failure and premature death from cardiovascular disease. Optimal glycaemic and BP control, including the use of RAAS blocking drugs, can prevent, slow and even reverse the processes causing DN.

Influence of ATII blockers and calcium channel blockers on renal vascular resistance in patients with essential hypertension

Doppler can evaluate renal vascular resistance, and resistance index (RI) highly correlates with blood pressure and renal function in various pathological conditions. Purpose of the study was to measure and compare renal Doppler indices in patients with newly-diagnosed essential hypertension (EH) and in healthy subjects; to determine changes of Doppler indices in patients after six-months monotherapy with either the AT II blocker (valsartane) or calcium channel blocker (niphedipine); to determine which drug has better renoprotective effect. 65 healthy controls were examined, as well as 69 patients with the newly-diagnosed EH, without signs of the target organ damage. Duplex Doppler US of interlobar intrarenal arteries was performed, and RI, acceleration index (AI) and acceleration time (AT) measured. Antihypertensive monotherapy was performed with vaslartane in 34 patients and with niphedipine in 35 patients. Doppler was repeated after the six-months therapy. RI in patients with the 1. stage of EH is significantly higher compared to the controls (p < 0.001), and significantly lower compared to the stage 2. of EH (p < 0.001). The significant decrease of systolic (p < 0.001) and dyastolic blood pressure (BP) (p < 0.001) was noted after the therapy. RI in healthy examinees (RI = 0.59 +/- 0.023) is significantly lower than in EH (RI = 0.66 +/- 0.26) (p < 0.001), while AI is significantly higher (p < 0.001), and AT is significantly lower (p < 0.001). In patients treated with valsartane and those treated with niphedipine, the RIs are significantly lower than before (p < 0.001), while AIs were significantly higher, and ATs were significantly lower after the therapy after the therapy with both drugs. RIs in patients treated with valsartane (RI = 0.615 +/- 0.036) are significantly lower than RIs of patients treated with niphedipine (RI = 0.642 +/- 0.030) (p < 0.01) after therapy. Regression analysis for the predictive values of RI, AT, AI in relation to the age-standardized values of systolic and diastolic BP of healthy examinees and patients with hypertension has demonstrated that RI is the strongest and statistically significant predictor in all groups of examinees. Six-months monotherapy of EH with valsartane or with niphedipine is equally efficient in the decrease of the blood pressure, but valsartane has more favourable effect on kidney. Resistance index measured in intrarenal arteries is the best parameter of Doppler spectrum in the evaluation of the effects of antihypertensive therapy on the kidney.

Olmesartan ameliorates renovascular injury and oxidative stress in Zucker obese rats enhanced by dietary protein

BACKGROUND

The metabolic syndrome is a risk factor for the development of renal and vascular complications. Dietary protein intake aggravates renal injury in Zucker obese rats, a model of the metabolic syndrome. This study investigated whether dietary protein intake enhances renal and vascular injuries by oxidative stress, and assessed effects of olmesartan, an angiotensin II type 1 receptor blocker, in this model.

METHODS

Zucker obese rats were fed either a standard protein diet, high protein diet (OHP), or high protein diet containing olmesartan or hydralazine for 12 weeks. We examined the glomerulosclerosis score, endothelium-dependent relaxation response in the aorta, 4-hydroxy-2-nonenal (HNE) contents in the kidney and aorta, and mRNA expression of NAD(P)H oxidase components (p22phox and p47phox) in the renal cortex.

RESULTS

The OHP rats developed proteinuria, glomerulosclerosis, and endothelial dysfunction. Olmesartan prevented the development of all these damages in OHP rats, whereas hydralazine improved only glomerulosclerosis. The high protein diet also augmented HNE accumulation in glomeruli, renal arteries, and aortas, and increased the mRNA expressions of p22phox and p47phox in the renal cortex in obese rats. Olmesartan, but not hydralazine, inhibited all these changes.

CONCLUSIONS

These results suggested that increased dietary protein intake exacerbates renal and vascular injuries, and augments oxidative stress in a rat model of the metabolic syndrome. Olmesartan ameliorated these injuries, presumably through its antioxidative effects, whereas hydralazine improved only glomerulosclerosis through its antihypertensive action. Dietary protein-enhanced injuries in the metabolic syndrome may be associated with hypercholesterolemia and the activated renin-angiotensin system.

Protective role of a novel erythrocyte-derived depressing factor on blood vessels of renovascular hypertensive rats

1. We have isolated a novel human erythrocyte-derived depressing factor (EDDF) that has a significant antihypertensive effect in various rat models of hypertension. The aim of the present study was to examine the mechanisms of action of EDDF on vascular function in two-kidney, one-clip (2K1C) renovascular hypertensive rats. 2. The EDDF was prepared from human erythrocytes. Experiments were performed in 18 male Wistar rats. The vascular ring perfusion assay and a two-photon laser scanning fluorescence microscope (TMP) were used to evaluate the vascular contractile response. The effects of EDDF on phenylephrine (PE)- and noradrenaline (NA)-induced vascular contraction were evaluated in 2K1C hypertensive rats. The proliferation and DNA synthesis in vascular smooth muscle cells (VSMC) were determined using the [3H]-TdR (thymidine) incorporation and 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Flow cytometry, reverse transcription-polymerase chain reaction and western blots were used to measure cell cycle and apoptotic profiles, platelet-derived growth factor (PDGF)-A expression and the activity of extracellular signal-regulated kinase (ERK)-1/2, as well as the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4. 3. At 10(-5) g/mL, EDDF significantly decreased the PE- and NA-induced hypertensive vascular contraction. In addition, EDDF inhibited DNA synthesis in primary VSMC from 2K1C rats. The mRNA expression of PDGF-A in VSMC was twofold higher in 2K1C rats compared with control rats, whereas EDDF significantly inhibited the increment in PDGF-A mRNA expression. In addition, EDDF inhibited the phosphorylation of ERK1/2 and decreased the expression of cyclin D1 and CDK4; p21 (Cip1) levels were increased after treatment with EDDF. 4. In conclusion, EDDF inhibits VSMC proliferation in 2K1C rats through G0/G1 cell cycle arrest. The effects may be mediated, in part, by enhanced expression of p21 (Cip1) and the inhibition of ERK1/2 phosphorylation and the expression of cyclin D1/CDK4 and PDGF-A.

Renovascular hypertension. 8 years experience of a vascular surgery centre

AIM

The aim of this study was to evaluate the technical success and clinical outcome of surgical revascularization, angioplasty and/or stenting for renal artery stenosis (RAS) in patients with renovascular hypertension (RVH). The secondary aim was to identify independent negative predictors of blood pressure control after successful renal revascularization.

METHODS

From January 1998 to July 2006, we treated 97 cases of RAS in 83 RVH patients. Inclusion criteria were RAS > or =80% associated with hypertension refractory to medical control with at least three drugs including a diuretic. Therapeutic options were surgical revascularization in 15 cases (11 renal endarterectomies, 4 aortorenal bypasses) and endoluminal treatment in 82 (14 balloon angioplasties, 68 stents).

RESULTS

Technical success was 100% for both surgical and endovascular procedures; 13 cases of restenosis (> or =80%) were detected: 12 (14.6%) in the endoluminal group and one (6.6%) in the surgical group (P=0.68). During the follow-up period (average 37 months, range 6-94), blood pressure control improved in 43% of patients, disease stabilized in 37% and the natural course of RVH deteriorated in 20%. Multivariate Cox regression analysis showed that only a long history of antihypertensive drug use was a predictor of inefficacy of blood pressure control after revascularization (P<0.04).

CONCLUSION

The complete resolution of RVH associated with severe RAS appears unrealistic in several cases. Early and long-term results in terms of technical success and restenosis were acceptable and similar for surgical and endovascular renal intervention. An early diagnosis of RVH could improve the control of hypertension after successful renal revascularization.

Prevention of Hypertension and Organ Damage in 2-Kidney, 1-Clip Rats by Tetradecylthioacetic Acid

Dietary lipids are reported to affect the blood pressure in both humans and experimental animal models with hypertension. In the present study, 2-kidney, 1-clip (2K1C) hypertensive rats were treated with the modified fatty acid tetradecylthioacetic acid (TTA) from the time of clipping or after hypertension was established. TTA treatment attenuated the development of hypertension and reduced established 2K1C hypertension. The mRNA level of renin in the clipped kidney and the plasma renin activity were markedly reduced, and the plasma angiotensin II level tended to decrease after TTA treatment. In addition, TTA reduced the mRNA level of angiotensinogen in white adipose tissue. Prevention of organ damage was demonstrated by normal urinary excretion of protein, maintained serum albumin, lower heart weight, and clearly reduced vascular, glomerular, and tubulointerstitial damage in the nonclipped kidney. Renal function was not affected as estimated by unchanged plasma creatinine. Furthermore, the serum levels of triacylglycerol and cholesterol were reduced by TTA. The serum fatty acid composition was changed, resulting in a favorable increase of oleic acid. However, the levels of all of the omega-3 fatty acids and of linoleic acid were reduced, and no change was seen in the level of arachidonic acid, but the urinary excretion of 8-iso-prostaglandin F2α was declined. In conclusion, TTA attenuated the development of hypertension, reduced established hypertension, and prevented the development of organ damage in 2K1C rats, possibly by reducing the amounts of the vasoconstrictors angiotensin II and 8-iso-prostaglandin F2α and by inducing a favorable increase of oleic acid in serum.

[ACE-inhibitors in renal protection]

The renal impairment due to hypertension causes the disturbance of the renin-angiotensin-aldosterone system which is accompanied with increased activity of the sympathetic nervous system. Administration of angiotensin-converting enzyme inhibitors decreases the production of angiotensin II, secretion of aldosterone, sodium and water retention and peripheral vascular resistance which altogether lead to the reduction of blood pressure. The nephro-protective efficacy of angiotensin-converting enzyme inhibitors was also proved by plenty of extensive international trials both in diabetic and non-diabetic patients with renal diseases. On evidence based medicine we may consider angiotensin-converting enzyme inhibitors and angiotensin receptor blockers--provided there are no contraindications as the standard therapy in all hypertensive and renal diseases.

[Sequelae of hypertenson: kidney disease]

Nephropathy is one of the frequent sequelae of hypertension. Arterial hypertension causes both arterial and capillary changes in the kidneys as well as development of interstitial fibrosis. Systemic or intraglomerular pressure increase leads to albuminuria and proteinuria, which in turn contributes to further damage of the kidneys. Impairment of the kidneys due to hypertension can ultimately result in terminal renal insufficiency necessitating dialysis. Metabolic factors such as hyperlipidemia, hyperuricemia, hyperhomocysteinemia, and insulin resistance can aggravate renal lesions. Effective lowering of blood pressure in conjunction with management of the metabolic risk factors is decisive for prevention of chronic kidney disease, which in turn must be considered a factor involved in exacerbation of the hypertension.

An update on renovascular hypertension

Renovascular hypertension (RVH) represents a secondary and potentially remediable form of hypertension. Elevated blood pressure is only one of a broad array of pathophysiologic consequences that are associated with decreased renal perfusion. Our ability to accurately and noninvasively detect stenotic lesions within the renal artery is growing. However, functional assessment of renal parenchyma and hemodynamic significance of renal artery lesions is still limited. Advances in endovascular techniques spurred interest in the concept of ischemic nephropathy and the effect of renal artery revascularization on renal function. Despite the relative frequency of atherosclerotic renal artery stenosis (ARAS), there currently is no consensus on the most appropriate therapy. In this article, we focus on the two most common causes of RVH, ARAS and fibromuscular dysplasia. We discuss the therapeutic strategies, disease mechanisms, clinical findings, evolving trends, and developments.

Effects of sesamin on aortic oxidative stress and endothelial dysfunction in deoxycorticosterone acetate-salt hypertensive rats

In the present study, we evaluated the relationship between the antihypertensive effect of sesamin, a lignan from sesame oil, and its antioxidative activity in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. After a 5-week treatment period, systolic blood pressure was significantly elevated in normal diet-fed DOCA-salt animals compared with cases in sham-operated animals. Sesamin feeding, tempol (a superoxide dismutase mimetic) treatment or antihypertensive drugs combination (triple therapy; reserpine, hydralazine, hydrochlorothiazide) significantly suppressed the development of DOCA-salt-induced hypertension. Compared with sham-operated rats, the normal diet-fed DOCA-salt rats revealed marked increases in aortic superoxide (O(2)(-)) production. These increases in O(2)(-) production were significantly suppressed by sesamin feeding or tempol treatment, but not by triple therapy. Acetylcholine (Ach)-induced endothelium-dependent relaxation was markedly decreased in normal diet-fed DOCA-salt rats, compared with cases in sham-operated rats. Sesamin feeding and triple therapy significantly improved the DOCA-salt-induced impairment of endothelium-dependent relaxation. However, tempol treatment had no effect on the impaired vasodilator responses induced by DOCA-salt treatment. In DOCA-salt rats with or without sesamin feeding, systolic blood pressure significantly correlated with both aortic O(2)(-) production and endothelium-dependent vascular relaxation. These findings suggest that sesamin feeding inhibits the enhancement of aortic O(2)(-) production in DOCA-salt hypertensive rats, and this effect may contribute to the antihypertensive effect of sesamin. Sesamin feeding-induced improvement of endothelial dysfunction seems to result from the above antioxidative and antihypertensive effects.

[Type 2 diabetic nephropathy: clinical course and prevention proposals 2004]

The first clinical evidence of nephropathy is the appearance of low, but abnormal, albumin levels in the urine (>30 mg/day or 20 mg/min), microalbuminuria. Without specific interventions, approximately 80% of type 1 diabetics have their urinary albumin excretion increase at a rate of 10-20%/yr to the stage of overt nephropathy or clinical albuminuria (>300 mg/24h or >200 mg/min) over 10-15 yrs, developing hypertension along the way. Approximately 30% of individuals with type 2 diabetes are found to have microalbuminuria or overt nephropathy shortly after the diagnosis of their illness, because diabetes is actually present for many years previously and because the presence of albuminuria can depend on other concomitant nephropathies, as shown by biopsy studies. Without specific intervention, 20-40% of type 2 diabetic patients with microalbuminuria progress to overt nephropathy, but 20 yrs after onset only 20% progress to end-stage renal failure (ESRD). The rates of decline in glomerular filtration rate (GFR) are highly variable from one individual to another, but they may not be substantially different between patients with type 1 and type 2 diabetes. As therapies and interventions for coronary artery disease continue to improve, more elderly type 2 diabetes patients can be expected to survive long enough to develop renal failure. The recently published Italian Society of Nephrology (SIN) guidelines for diagnosis and therapy of diabetic nephropathy present the route for the best strategies in prevention and therapy, from earlier onset to advanced ESRD.

Effects of calcium antagonists in hypertensive patients with renal dysfunction: a prospective, randomized, parallel trial comparing benidipine and nifedipine

BACKGROUND

Although calcium antagonists, derived from dihydropyridine (DHP), are important agents in achieving control in a majority of patients with high blood pressure and renal disease, there are no comparative data regarding their inhibitory effects on the progression of renal dysfunction in Japan.

METHODS

Benidipine and nifedipine retard both calcium antagonists derived from DHP and were compared in terms of their inhibitory effect on the progression of renal dysfunction in hypertensive patients. The primary end-points were defined as 1.5 times the serum creatinine value at baseline, progression to end-stage renal failure (ESRF) necessitating dialysis or renal transplantation, and death.

RESULTS

During the study period, a significant decline in blood pressure was observed in the two groups, with no significant difference between them. The worsening of nephropathy was significantly inhibited in the benidipine group as compared with the nifedipine retard group (log-rank test: P = 0.014, Wilcoxon's test: P = 0.022). Among the subjects who reached a primary end-point, one (33%) in the benidipine group and five (50%) in the nifedipine retard group were placed on haemodialysis within 1 year.

CONCLUSION

It appears that benidipine inhibits the progression of hypertensive renal diseases more effectively than nifedipine retard.

Cardioprotective Action of Perindopril versus Candesartan in Renovascular Hypertensive Rats

We investigated the effects of an angiotensin-converting enzyme inhibitor and an angiotensin II type 1 receptor blocker on cardiac hypertrophy in rats with renovascular hypertension. Renovascular hypertensive (Goldblatt) rats were surgically prepared from Wistar rats. Four weeks later, the rats showed a significant increase in blood pressure. At high doses, both the perindopril (1 mg/kg/day) and the candesartan (2 mg/kg/day) decreased the systolic pressure in these rats to the level of control Wistar rats. At low doses (perindopril 0.1 mg/kg/day and candesartan 0.1 mg/kg/day), these drugs lowered blood pressure to 85% of that in hypertensive rats. Echocardiographic and morphological studies revealed severe cardiac hypertrophy and fibrosis in untreated Goldblatt rats. High-dose treatment with both drugs suppressed the progression of hypertrophy and fibrosis. Also, low-dose perindopril prevented cardiac hypertrophy and fibrosis. In contrast, at the same levels of blood-pressure reduction, low-dose candesartan did not prevent cardiac fibrosis nor the upregulation of cardiac collagen types I and III mRNA observed in untreated Goldblatt rats. Atrial natriuretic peptide mRNA was up-regulated in untreated Goldblatt rats. These changes were significantly decreased by both doses of perindopril or the high dose of candesartan. Serum levels of angiotensin II and aldosterone were significantly higher in untreated Goldblatt rats. Both doses of perindopril inhibited activation of the renin-angiotensin system, whereas candesartan had weaker effects. In particular, serum aldosterone was 347 +/- 20 pg/ml in low-dose perindopril versus 1796 +/- 324 pg/ml in low-dose candesartan. These results suggest that there were no differences between the cardioprotective actions of perindopril and candesartan at high dosages. On the other hand, low-dose treatment with perindopril was more effective in preventing cardiac fibrosis than was low-dose treatment with candesartan, despite similar changes in blood pressure. It is possible that changes in aldosterone secretion are related to this difference.

Prevention of hypertension attenuates albuminuria and renal expression of fibronectin in diabetic spontaneously hypertensive rats

BACKGROUND/AIM

The aim of this study was to evaluate the effect of preventing hypertension on renal disease in a model of genetic hypertension and diabetes.

METHODS

Four-week-old spontaneously hypertensive rats (SHR) with streptozotocin-induced diabetes were randomized for no treatment, or for treatment with captopril, losartan or triple therapy (hydrochlorothiazide, reserpine and hydralazine) for 16 weeks.

RESULTS

Increase in systolic blood pressure was equally prevented by captopril (128 +/- 3 mm Hg), losartan (128 +/- 2) and triple therapy (129 +/- 2, p < 0.0001). Albuminuria was similarly reduced by captopril (499 (404-659)), losartan (622 (470-976)) and triple therapy (479 (362-600) microg/24 h (p < 0.0001)). Renal fibronectin expression increased in diabetic SHR (125 +/- 13 densitometric unit) as compared to the controls (51 +/- 9, p < 0.0001), and decreased (p < 0.0001 vs. diabetic SHR) with captopril (32 +/- 8), losartan (27 +/- 4) and triple therapy (35 +/- 6).

CONCLUSION

The prevention of hypertension in diabetic SHR by captopril, losartan or triple therapy was equally efficacious in impeding increase of albuminuria and the expression of renal fibronectin. Under these conditions, tight blood pressure control was the main determinant in attenuating nephropathy.

Atherosclerotic renal arterial stenosis: clinical outcomes of stent placement for hypertension and renal failure

PURPOSE

To assess technical success rates and long-term clinical outcomes of primary renal arterial stent placement in atherosclerotic renal arterial stenosis (RAS).

MATERIALS AND METHODS

Primary stent placement was performed in 100 consecutive patients with atherosclerotic RAS. Indications for treatment were resistant hypertension (n = 25), impaired renal function, (n = 50), and both (n = 25). Immediate technical results were evaluated with angiography. Clinical outcomes were assessed with serial systolic and diastolic blood pressure and serum creatinine values obtained from retrospective review of case notes. Results obtained every 6 months after the procedure were compared with those obtained at the time of the procedure with the paired t test. Radiologic reports were evaluated for immediate and case notes for delayed complications.

RESULTS

Technical success was achieved in 120 (95.2%) of 126 RAS in 95 patients. Mean follow-up was 25 months (median, 24 months; range, 1-66 months). Resistant hypertension was cured in two (4.2%) of 48 patients, had improved in 38 (79.1%), and had failed to respond to treatment in eight (16.7%). Mean systolic and diastolic blood pressures were significantly lower at 6, 12, 18, 24, and 30 months (P <.01) than before the procedure. Among 65 patients treated for renal impairment, renal function improved in 20 (30.8%), stabilized in 25 (41.7%), and continued to deteriorate in 20 (30.8%). The mean serum creatinine level did not show significant change with time for this group. In the improved subgroup, it was significantly higher at 6, 12, 18, 24, 36, and 42 months (P <.05) than prior to the procedure. Procedure-related complications occurred in 18 (18%) cases: Ten were minor and self-limiting and eight were major and included two procedure-related deaths.

CONCLUSION

In atherosclerotic RAS, primary stent deployment has a high technical success rate, producing clinical benefits in the majority of patients when performed for resistant hypertension and recovery of renal function.

Reconstruction for renal artery aneurysm: operative techniques and long-term results

BACKGROUND

Ninety-four patients (37 male, 57 female; mean age, 51.0 years) underwent reconstruction for renal artery aneurysm (RAA) between 1980 and 2001. RAAs were present in 52 patients in the right kidney, in 29 patients in the left kidney, and in 13 patients in both kidneys. Eighty-three aneurysms were located in the mainstem, 49 in a branch artery, and four in an accessory artery. Additional ipsilateral renal artery stenoses (RAS) occurred in 26 patients, bilateral RAS in 18, and contralateral RAS in six. The causes of RAA were fibromuscular dysplasia (n = 48), atherosclerosis (n = 28), dissection (n = 7), aortic coarctation (n = 5), arteritis (n = 3), giant cell arteritis (n = 1), Marfan's syndrome (n = 1), and trauma (n = 1). Seventy-five patients had hypertension, 14 were asymptomatic, and five had rupture. Indications for RAA repair concerned aneurysms with 1 cm or more diameter in combination with risk factors of hypertension, ipsilateral and contralateral stenosis, and childbearing age in women. Without risk factors, aneurysm size eligible for reconstruction was limited to 2 cm or more.

METHODS

Methods applied for reconstruction in 107 kidneys and 136 aneurysms included aneurysm resection with tailoring (n = 37), saphenous vein graft interposition (n = 40), tailoring and saphenous vein graft interposition (n = 7), resection and reanastomosis (n = 14), saphenous vein graft interposition and resection and reanastomosis (n = 3), polytetrafluoroethylene bypass (n = 5), and homologous vein graft interposition (n = 1). Four reconstructions had to be performed ex situ because of multiple branch involvement in three patients and rupture in one. In all patients, the concerned kidney was protected with hypothermic flush perfusion with addition of heparin and prostaglandin E1.

RESULTS

The overall morbidity rate was 17%, including one early graft occlusion, one partial thrombosis of the renal artery that necessitated fibrinolytic therapy, and a branch artery stenosis after tailoring managed with aortorenal bypass. The mortality in elective cases was null; one patient died of myocardial infarction 2 days after an emergency operation for ruptured RAA. The technical primary success rate was 96.8%; the secondary success rate was 98.9%. After a follow-up period from 1 to 143 months (mean, 46 months) in 83 patients (88%), 67 (81%) had patent renal arteries free of stenoses. Among six patients with RAS, four underwent successful reoperation, five had mainstem occlusions, three had segmental artery occlusions, and two underwent nephrectomy. Concerning the patients who underwent reoperation, percutaneous transluminal angioplasty was considered seriously but assessed as inappropriate because of long extension of stenosis or involvement of branch arteries. Hypertension was cured in 19 patients (25%) and improved in 17 (22%).

CONCLUSION

Surgical reconstruction of RAA is a safe procedure that provides good long-term results, prevents aneurysm rupture, cures or improves hypertension in about half of the cases, and can be achieved with autogenous reconstruction in 96%.

[Renal mechanisms of protective potassium effect in essential hypertension]

In experiments on nonlinear rats, the renal functions were investigated at aqueous diuresis induced by intragastric administration of sodium potassium, potassium hydrocarbonate (20 mM/kg), and potassium succinate (10 mM/kg). We have found that the load by potassium raised glomerular filtration rate and sharply increased excretion of not only K+ but also Na+ and Cl- with urine, that led to hyponatremia and hypochloremia following hyperkalemia. In addition, the intracellular concentration of K+ increased more than extracellular one, especially after administrating KHCO3 and potassium succinate. It promoted potassium efflux from cells by concentration gradient, hyperpolarization of cellular membrane and vascular smooth muscle relaxation. Thus, these data explain renal mechanisms of a known protective effect of potassium at essential hypertension.

[Effect of praeruptorum caumarin on cardiac mass, myocardial [Ca2+]i and Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase activity in renovascular hypertensive rats]

AIM

To investigate the preventive and reversional effect of praeruptorum caumarin compound on left ventricular hypertrophy in renovascular hypertensive rats (RHR) and its mechanism.

METHODS

The two-kidney-one-clip (2K1C) RHR model was used. The blood pressure, wet weight of the left ventricle, surface area of myocardial cells, resting [Ca2+]i level and Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase activity of myocardial membrane and mitochondria were measured.

RESULTS

Praeruptorum caumarin 30 mg.kg-1.d-1 was given ig for 9 weeks from the 6th or 9th week after operation in the preventive or regressive group. The blood pressure, left ventricle wet weight and area of myocardial cells of the preventive and regressive group were significantly reduced than that of the LVH group. The resting [Ca2+]i of the both praeruptorum caumarin treated groups (121 +/- 13, 133 +/- 9 nmol.L-1) were lower than that of the LVH group (158 +/- 7 nmol.L-1). The KCl-induced [Ca2+]i elevation was decreased more significantly in preventive and regressive group than that of the hypertrophic myocytes. The activity of Na+, K(+)-ATPase and Ca2+, Mg(2+)-ATPase increased by 40% and 93% in the preventive group, 28.4% and 48.8% in regressive group than that of the LVH group.

CONCLUSION

Praeruptorum caumarin was shown to prevent and reverse hypertrophy of LVH by lowering [Ca2+]i and increasing the ATPase activity.

Renal cortical remodelling by NO-synthesis blockers in rats is prevented by angiotensin-converting enzyme inhibitor and calcium channel blocker

The cortical remodelling was studied when chronically nitric oxide synthesis (NOs) blockade (L-NAME-induced) hypertensive rats are simultaneously treated, or not, with angiotensin-converting enzyme inhibitor or calcium channel blocker. Four groups of eight rats each were studied as follows: Control (C), L-NAME (L), L-NAME+Enalapril (L+E) and L-NAME+Verapamil (L+V). The systolic blood pressure (SBP) was weekly recorded. The cortex of the left kidneys was analysed according to the vertical section design. The volume-weighted mean glomerular volume (VWGV) was made through the "point-sampled intercepts" method. Enalapril and verapamil were efficient in reducing the SBP in rats submitted to NOs blockade. Glomeruli had considerable alterations in L group rats (glomerular hypertrophy or sclerosis) and tubular atrophy. The VWGV was 100% greater in L group rats than in the C group rats, while it was 30% smaller in L+E and L+V groups than in L group. The tubular volume was 30-50% greater, while the tubular length was 20-30% smaller in the L group than in the other groups. The renal cortical region showed glomerular sclerosis/hypertrophy and tubular remodelling in rats with NOs blockade that was efficiently prevented with the simultaneous treatment with enalapril or verapamil.

Regression of renal vascular fibrosis by endothelin receptor antagonism

In previous studies, we have observed that endothelin participates in the progression of renal vascular and glomerular fibrosis during hypertension by activating collagen I gene synthesis. The present study investigated whether administration of endothelin receptor antagonists leads to the regression of renal sclerotic lesions. Experiments were performed in transgenic mice harboring the luciferase gene under the control of the collagen I-alpha2 chain promoter. Hypertension was induced by long-term inhibition of nitric oxide synthesis by N(G)-nitro-L-arginine methyl ester (L-NAME); systolic pressure gradually increased, reaching a plateau of 165 mm Hg after 10 weeks of hypertensive treatment. At the same time, collagen I gene expression was increased 2- and 5-fold compared with control animals in afferent arterioles and glomeruli, respectively (P<0.01). This increase was accompanied by the appearance of sclerotic lesions within the renal vasculature. When renal vascular lesions had been established (20 weeks of L-NAME), animals were divided into 2 subgroups: the one continued to receive L-NAME, whereas in the other, bosentan, a dual endothelin antagonist, was coadministered with L-NAME for an additional period of 10 weeks. Bosentan coadministration did not alter the increased systolic pressure at 30 weeks; in contrast, collagen I gene activity returned almost to control levels in renal vessels and glomeruli. In this subgroup of animals, renal vascular lesions (collagen and/or extracellular matrix deposition) and mortality rates were substantially reduced compared with untreated mice. These data indicate that endothelin participates in the mechanism(s) of renal vascular fibrosis by activating collagen I gene. Treatment with an endothelin antagonist normalizes expression of collagen I gene and leads to the regression of renal vascular fibrosis and to the improvement of survival, thus providing a complementary curative approach against renal fibrotic complications associated with hypertension.

Cardiorenal protection in diabetes

Diabetes is twice as common in hypertensive patients than in the general population, and is a major cause of cardiovascular morbidity. Diabetes is the most common cause of end-stage renal disease in the United States, and is primarily responsible for the 9% increase in prevalence of end-stage renal disease during the past 10 years. However, there is evidence that tight blood-pressure control can reduce the vascular complications of diabetes. This reduction was demonstrated in the United Kingdom Prospective Diabetes Study, in which patients who were randomized to a tight blood-pressure control group had 24% fewer vascular complications (including strokes and diabetic retinopathy) than patients in usual-care groups. Thus, the target goal for blood pressure in patients with diabetes is 130/85 mmHg. Microalbuminuria is an early marker of diabetic nephropathy, and is most pronounced in patients whose 24-hour blood pressure shows a nondipping pattern (failure of the blood pressure to fall at night). The prevalence of nondipping blood pressure is increased in patients with diabetes and in patients with renal disease due to other causes. Further, there is evidence that patients with nondipping blood pressure show more rapid deterioration of renal function than patients with dipping blood pressure. High nocturnal pressure in patients with nondipping blood pressure may accelerate glomerular damage. For example, studies of animals with diabetes have shown that the afferent glomerular arteriole is dilated when compared with the efferent arteriole, thereby exposing the glomerulus to the systemic arterial pressure. Numerous studies have shown that angiotensin-converting enzyme (ACE) inhibitors are superior to some antihypertensive agents (particularly beta blockers and diuretics) in the prevention of renal damage. This observation is based on results of a metaanalysis that demonstrated a 9%/year glomerular filtration rate decrease in patients taking beta blockers or diuretics, but only a 1%/year decrease in patients taking ACE inhibitors. The role of calcium channel blockers is more controversial, but there is evidence to suggest that nondihydropyridine calcium channel blockers may confer the same benefit as ACE inhibitors. Alpha blockers and angiotensin-receptor blockers show promise, but have been less widely studied.

Utility of coaxial technique for renal angioplasty in patients with a difficult-to-cross stenosis

The aim of this study was to evaluate the feasibility of coaxial approach in difficult-to-cross lesions in patients with failed percutaneous transluminal renal angioplasty by conventional over-the-wire exchange technique. Twelve stenoses in 10 patients (six women and four men; age range 19 +/- 7 years) with uncontrolled hypertension were treated by this method. The stenosis was caused by nonspecific aortoarteritis in 8 patients and fibromuscular dysplasia in 2 patients. It was ostial in seven and post-ostial in five vessels. Conventional exchange technique was unsuccessful in all of them. All procedures were done by femoral route. Technical success was seen in 11 (92%), without complication. The stenosis improved from 90 +/- 2.1% (range 80-100%) to 6 +/- 7% (range 0-20%), blood pressure decreased from 198 +/- 12.3 mm Hg (range 180-220 mm Hg)/130 +/- 6.7 mm Hg (range 120-140 mm Hg) to 119 +/- 5.7 mm Hg (range 110-130 mm Hg)/83 +/- 3.9 mm Hg (range 80-90 mm Hg), and number of drug treatments for hypertension fell from 3.6 +/- 0.52 (range 3-4) to 1 +/- 0.94 (range 0-3; p < 0.01). Percutaneous transluminal renal angioplasty resulted in "cure" in 3 patients and "improvement" in 7 patients. Follow-up period was 3-21 months (mean 6.4 months). No restenosis was detected. Coaxial approach is safe and effective in treating difficult-to-cross lesions in which renal angioplasty by conventional exchange technique is unsuccessful.

L-arginine restores the effect of ouabain on baroreceptor activity and prevents hypertension

In spontaneously hypertensive rats, ouabain exerts an excitatory effect on baroreceptor nerve activity (BNA). The aim of this study was to determine the effects of ouabain on BNA in other experimental models of hypertension and its interaction with nitric oxide. Rats were made hypertensive using the procedures for N(omega)-nitro-L-arginine methyl ester (L-NAME), deoxycorticosterone acetate (DOCA) salt, and 2-kidney, 1 clip (2K1C) hypertension models. In these groups, systolic arterial pressure was 195+/-7, 149+/-6, and 148+/-4 mm Hg, respectively, compared with 110+/-4 mm Hg in normotensive rats. Acute ouabain administration had an excitatory effect on BNA in normotensive rats (37+/-4%), an inhibitory effect in L-NAME hypertensive rats (-60+/-7%), and no effect in DOCA-salt and 2K1C hypertensive rats. The effects of ouabain were not related to arterial pressure levels, and no excitatory effect on BNA was observed in prehypertensive DOCA-salt rats. Long-term administration of L-arginine (3 g x kg(-1) x day(-1)) prevented DOCA-salt (121+/-8 mm Hg) and 2K1C (104+/-4 mm Hg) hypertension, markedly attenuated L-NAME (130+/-9 mm Hg) hypertension, and restored the excitatory effect of ouabain on BNA in these groups to levels similar to the normotensive rats and their respective control groups. We conclude that ouabain has a diverse effect on BNA in experimental models of hypertension, and it can be normalized by L-arginine. The data also indicate that nitric oxide may play a pivotal role in mediating the excitatory effect of ouabain on BNA, and we speculate that a therapeutic combination of ouabain and L-arginine may be beneficial in secondary hypertension.

Stents for atherosclerotic renovascular disease

There is extensive documentation of excellent clinical results with renal stents in patients who have technically failed angioplasty and who would have been expected to otherwise have a high incidence of clinical failure. In addition, the technical success of renal stents is vastly superior to that of conventional angioplasty in atherosclerotic renovascular disease, and stents have been a major factor in making the endovascular treatment of ASRVD both practical and reliable in experienced hands. Restenosis rates appear roughly equivalent or lower for stents versus PTA as far as can be determined without good comparative studies. Restenosis appears to be decreasing to 15%-20% in more recent series, perhaps because of the accumulation of knowledge regarding patient selection and techniques. It is, therefore, clear that the use of stents to treat technical failures of angioplasty will result in overall improved patency in the treated population; however, it remains to be determined whether stents should be routinely placed with the intention of inhibiting restenosis, in the presence of technically successful angioplasty with minimal residual stenosis or pressure gradient. Such a determination may require comparative study that is more complicated than a simple randomized comparison of angioplasty versus stents.

Partial renal embolization for pediatric renovascular hypertension secondary to fibromuscular dysplasia

We report a 7-year-old boy with renovascular hypertension showing multiple stenoses and microaneurysms of the dorsal branch of the left renal artery caused by fibromuscular dysplasia. Hypertension was successfully treated with transcatheter alcohol and gelatin sponge embolization of the dorsal branch and its distribution. The vertebral branch remained intact. No severe complication was encountered. Loss of renal function by renal scintigraphy was minimal. The patient remains asymptomatic at 1 year.

A review of captopril renal scintigraphy and its effect on patient management

Renal artery stenosis is an important and potentially curable cause of hypertension. Captopril renography is now recognized to have a high sensitivity and specificity in its diagnosis. Ultimately, however, the result is of little benefit if it does not lead to a change in patient management. To assess how patient management was changed following the result of a captopril renogram, we reviewed the notes of 95 patients who had undergone this test over a 5 year period to identify renal artery stenosis. Of these patients, significant renal artery stenosis was suggested in 16 (17%), of whom only 9 (56%) underwent a change in management (7 proceeding to angiography with or without angioplasty, 2 having alterations in medication). In the 67 patients who had a negative renogram, 16 (24%) had an alteration in management (13 angiography, 3 altered drug treatment). Finally, of the 12 patients who had a non-diagnostic renogram, 7 (60%) had a management change (3 angiography, 4 altered drug therapy). Our results suggest that, despite evidence from the literature that captopril renography is both sensitive and specific for renal artery stenosis, clinicians still rely on other factors when determining who has significant stenosis and, therefore, who should proceed to a further investigation or have a change in medication. Ultimately, this reduces the clinical value of the test at present.

[Screening and diagnosis for eliminating renovascular hypertension. Value of 24-hour blood pressure monitoring and color-coded duplex ultrasound diagnosis]

BACKGROUND

Direct renal angiography is still the method of choice for identification of renal artery stenosis. Newer non-invasive diagnostic methods include color coded duplex sonography and also ambulatory 24-h blood pressure monitoring, since in a large proportion of patients with secondary forms of hypertension the usual blood pressure fall during nighttime disappears.

PATIENTS AND METHODS

In a prospective in-hospital study we investigated 86 patients with suspected renovascular hypertension. Circadian blood pressure was measured oscillometrically and color coded duplex sonography was performed immediately before direct renal angiography.

RESULTS

Angiography revealed renal artery stenosis (> or = 50%) in 42 patients. This compared to a sensitivity of 92.9% and specificity of 91.7% for the use of sonography in those patients (70.4%) who could be adequately examined. Mean 24-h pressure values as well as standard deviations of blood pressure means as an indicator for blood pressure variability were not different in the 2 groups of patients, when all the data were analysed together and also when the data for nighttime and daytime were examined separately. The percent of blood pressure fall during nighttime was also not different in the 2 groups. In both groups 4 hypertensive patients had a blood pressure increase during nighttime. In 11 patients without renal artery stenosis a blood pressure fall of < 10% was observed, compared to 12 patients with renal artery stenosis. The circadian pattern of pulse rate was similar in both groups.

CONCLUSION

We conclude that ambulatory blood pressure monitoring has a considerably lower diagnostic value for renal artery stenosis compared to angiography and also to color duplex sonography. This method therefore does not appear to be an appropriate screening approach for this kind of secondary hypertension. The color coded duplex sonography, however, seems to be the best non-invasive diagnostic method in those patients, who can be adequately examined.

Suppression of sympathetic nervous system attenuates the development of two-kidney, one-clip Goldblatt hypertension

PURPOSE

This study tried to assess the possible contribution of the sympathetic nervous system to the onset of two-kidney, one-clip (2K-1C) Goldblatt hypertension.

MATERIALS AND METHODS

The effect of chlorisondamine administration with or without subsequent splanchnicotomy on the development of hypertension was examined in 2K-1C rats with special reference to norepinephrine synthesis.

RESULTS

The 2K-1C rats were treated either with chlorisondamine or chlorisondamine plus subsequent splanchnicotomy, so that the development of hypertension was effectively arrested for 4 weeks. An apparently high rate of release of norepinephrine in 2K-1C rats was reduced by treatment with chlorisondamine plus splanchnicotomy. A similar trend was also seen in plasma norepinephrine concentration and norepinephrine clearance, to a lesser extent. There were significant positive relationships between percent change of systolic blood pressure and apparent rate of release of norepinephrine, plasma norepinephrine concentration and norepinephrine clearance in 2K-1C rats and 2K-1C + chlorisondamine + splanchnicotomy rats. There were no significant relationships in these parameters in sham-treated rats.

CONCLUSION

Increased sympathetic innervation appears to participate in the development of 2K-1C Goldblatt hypertension.

[Rational hypertension treatment]

The primary objective of antihypertensive treatment is to prevent the involvement of target-organs, including hypertensive vascular disease of the kidney or left ventricular hypertrophy. Antihypertensive treatment should not worsen other cardiovascular risk factors (e.g. lipids) or impair quality of life. Contemporary efforts to optimize antihypertensive therapy are focused on single-drug therapy and on individualizing treatment according to patients age, sex, race and the presence of concomitant illnesses and therapies, in order to improve compliance and reduce overall cardiovascular morbidity and mortality. Several antihypertensive drugs such as ACE-inhibitors, beta-adrenergic-receptor antagonists, calcium channel blockers, diuretics, alpha-adrenergic-receptor antagonists, and newer substances such as imidazoline-receptor antagonists and angiotensin-II antagonists are discussed.

Effect of primary balloon expandable renal artery stents on long-term patency, renal function, and blood pressure in hypertensive and renal insufficient patients with renal artery stenosis

Stents were deployed in 83 renal artery lesions of 63 subjects. All were hypertensive and 29 were renal insufficient (RI). Technical success was 99%. Long-term (11.3 +/- 3.8 months) patency was evaluated with ultrasound in 69 lesions (51 ostial). Technical success and long-term patency rates were not significantly different between ostial and non-ostial lesions. Ten lesions restenosed (14%). At most recent follow-up (10.2 +/- 4.5 months) hypertensive subjects were classified as cured (3.7%), improved (35.2%), unchanged (53.7%), or worse (7.4%). Systolic pressure was significantly improved throughout follow-up but diastolic pressure was only significantly lower at discharge. Based on serum creatinine, Rl subjects were classified as improved (36%), unchanged (46%), or worse (18%). Complications included transfusion (10), renal artery perforation (3), and renal failure (8). Eight transfused subjects also had retroperitoneal bleeds. Rl subjects were more likely to develop acute renal failure. Subjects who died (9) were more likely to have Rl at baseline and to suffer renal artery perforation during the procedure. Patient risk factors and procedural technique contributed to complications in this study, but for most patients stenting yielded excellent technical success and long-term patency for ostial and non-ostial lesions. The effect on blood pressure and renal function was favorable.

Renal effects of a high unsaturated fat diet in renal artery stenosis in rats

The renal effects of an unsaturated fat (UNSAT) diet in mild to moderate two-kidney, one-clip (2K1C) renovascular hypertension were evaluated. An UNSAT diet (37% by energy) prevented the development of hypertension compared to 2K1C rats fed a high saturated fat (SAT) (37% by energy) and a normal fat (CONTROL) (11% by energy) diet. Urinary sodium and fractional sodium excretion increased in 2K1C rats as compared to SHAM operated controls, regardless of the diet received. In the early weeks of the experiment (weeks 2-4 post-surgery to induce hypertension), an enhanced natriuresis occurred in the 2K1C UNSAT as compared to the 2K1C CONTROL and SAT diet groups. This resulted from an increase in the glomerular filtration rate (GFR in mls.min-1) as measured using the single-injection [51Cr] EDTA method (2K1C UNSAT; 1.99 +/- 0.18 versus 2K1C SAT; 1.27 +/- 0.09, p < 0.02; and versus SHAM CONTROL; 1.45 x 0.01; p < 0.02). The increased GFR was not associated with alterations in effective renal plasma flow (ERPF) as measured using the single-injection [125I] Na hippurate method. No differences in sodium excretion; GFR; ERPF or renal blood flow (microsphere technique) were noted between the 2K1C UNSAT and SAT diet groups at weeks 6-8 post-surgery, despite a continued antihypertensive effect of the UNSAT diet. Hence, the antihypertensive effect of an unsaturated fat diet in 2K1C renovascular hypertension in rats is associated with transient glomerular changes leading to an enhanced natriuresis.

Routine diagnostic imaging for childhood urinary tract infections: a systematic overview

OBJECTIVE

To assess the quality of the evidence on which current recommendations for routine diagnostic imaging for childhood urinary tract infection are based.

METHODS

A systematic overview of the literature using the MEDLINE database (1966 to October 1994), article bibliographies, and a manual search of current publications using Current Contents, was undertaken. Preset criteria were used to categorize study sample and design, and interrater reliability was assessed with a random sample.

RESULTS

A total of 434 publications were evaluated, and 63 studies met the criteria for inclusion. There was 100% interrater agreement on inclusion eligibility and design classification. No controlled trials or analytic studies evaluating routine diagnostic imaging were found. All 63 studies were descriptive, and only 10 were prospective. None of the studies provided evidence of the impact of routine imaging on the development of renal scars and clinical outcomes in children with their first urinary tract infection.

CONCLUSION

Methodologically sound, prospective studies are needed to assess whether children with their first urinary tract infection who have routine diagnostic imaging are better off than children who have imaging for specific indications. We conclude that the current recommendations are not based on firm evidence.

Antihypertensive effect of sesamin. II. Protection against two-kidney, one-clip renal hypertension and cardiovascular hypertrophy

We investigated the antihypertensive effect of sesamin, a lignan from sesame oil, using two-kidney, one-clip (2K,1C) renal hypertensive rats. After clipping the left renal artery, animals were assigned to either a normal diet group (control group) or a sesamin-containing (1% (w/w)) diet group (sesamin group). The sham-operated rats (sham group) were fed a normal diet and tap water. The systolic blood pressure of the control group increased progressively in comparison with the sham group. This 2K,1C-induced hypertension was markedly reduced by feeding the sesamin-containing diet. The systolic blood pressure after 4 weeks was 123.60 +/- 4.01 mmHg in the sham group, 187.43 +/- 5.69 mmHg in the control group and 145.57 +/- 6.78 mmHg in the sesamin group, respectively. There were significant increases in left ventricle plus septum weight-body weight ratio in the control group compared with the sham group. This rise was also significantly reduced in the sesamin group. When the thoracic aorta was histochemically evaluated, the wall thickness and wall-to-lumen ratio in the control group were significantly increased, compared with the sham group, indicating that vascular hypertrophy had occurred in the control group. The sesamin diet tended to ameliorate this vascular hypertrophy, although its effect was not statistically significant. These findings suggest that sesamin is useful as prophylactic treatment to combat the development of renal hypertension and cardiac hypertrophy.

Stenoses of renal branch arteries in fibromuscular dysplasia: results of percutaneous transluminal angioplasty

PURPOSE

To evaluate percutaneous transluminal renal angioplasty (PTRA) in the treatment of renal branch artery stenoses caused by fibromuscular dysplasia.

MATERIALS AND METHODS

The authors retrospectively studied the files of 20 consecutive hypertensive patients with 25 branch artery stenoses associated with 10 main renal artery lesions. Results at clinical and angiographic follow-up were assessed by means of life-table analysis.

RESULTS

PTRA was technically successful in 21 of the 25 renal branch artery stenoses (84%). One of the technical failures was treated by means of selective embolization. Nine of the 10 associated main renal artery lesions were successfully dilated, and the 10th was improved. Immediately after PTRA, at 6-month follow-up, and at long-term follow-up, 70%, 76%, and 68% of the patients, respectively, were cured and 25%, 24%, and 16% were improved. Stenosis recurred in 9% of the branch arteries and was associated with clinical relapse; these arteries were redilated, and all patients were considered cured at the second 6-month follow-up.

CONCLUSION

PTRA should be considered the first-line treatment for hypertension due to renal branch artery stenosis in fibromuscular disease.

Angiotensin AT1 receptor blockade by specific antibody prevented two-kidney, one-clip renal hypertension in the rat

The effect of chronic angiotensin AT1 receptor blockade by a specific antibody on the development of two-kidney, one-clip renal hypertension was studied in Wistar rats. Renal artery constriction resulted in a fast and large increase in blood pressure in comparison with that of control rats. On the other hand, the pre-immunization of rats with a small part of the angiotensin AT1 receptor completely prevented the development of renal hypertension. We conclude that the development of two-kidney, one-clip renal hypertension can be blocked by a specific antibody raised against a part of the angiotensin AT1 receptor.

Use of the thoracic aorta for renal arterial reconstruction

PURPOSE

Thoracic aortorenal bypass is a new technique for surgical renal revascularization in patients with severe atherosclerosis of the abdominal aorta. In such cases, the thoracic aorta is often free of disease.

METHODS

From 1989 to 1992, thoracic aortorenal bypass was performed in 23 patients with hypertension, abdominal aortic atherosclerosis, and celiac artery stenosis; in 21 patients, renal artery stenosis was present bilaterally or in a solitary kidney.

RESULTS

There was one operative death. Among the remaining 22 patients, hypertension was cured or improved after operation in 19 (86%), and renal function was improved or stable in 21 (95%).

CONCLUSIONS

Thoracic aortorenal bypass has several advantages and is a useful alternative to abdominal aortic replacement in selected older patients who require renal arterial reconstruction.

Renal artery stenosis: analysis of Doppler waveform parameters and tardus-parvus pattern

PURPOSE

The utility of Doppler parameters and waveform contour analysis for diagnosis of renal artery stenosis was studied in a hypertensive population screened for renovascular hypertension.

MATERIALS AND METHODS

The Doppler results were compared with those obtained with angiography in a prospective double-blind study involving 118 kidneys in 46 patients with hypertension and 11 potential renal donors with normal blood pressure. Doppler parameters measured in the distal renal artery included systolic acceleration, acceleration time, peak systolic velocity, deceleration in late systole, pulsatility and resistivity indexes, and waveform features in early systole.

RESULTS

Angiograms demonstrated 28 stenotic renal arteries. There was no significant difference between stenotic (> 50% diameter narrowing) and nonstenotic renal arteries for any parameters studied. When stenosis was further categorized as moderate (50%-79%) or severe (80%-95%), significant (P < .05) differences for acceleration time and systolic acceleration were found between nonstenotic and severely stenotic arteries.

CONCLUSION

Doppler characterization of the tardus-parvus phenomenon in the distal renal artery is not an adequate screening method for detection of renal artery stenosis.

The usefulness of the captopril test as a simultaneous screening for primary aldosteronism and renovascular hypertension

The usefulness of the captopril test as a simultaneous screening method for primary aldosteronism (PA) and renovascular hypertension (RVH) was evaluated in 111 patients with essential hypertension, and in 79 patients with secondary hypertension, which included 16 patients with PA and 18 with RVH. Plasma renin activity (PRA, ng/mL/h) and plasma aldosterone concentration (PAC, ng/dL) were determined before and 90 min after administration of 50 mg of captopril in the supine position on a normal NaCl diet. A cutoff point or a discriminant function in the screening was determined by discriminant analysis. A quadratic discriminant function of PRA and PAC after the captopril test identified patients with PA with a false negative rate of 6.3% (1/16), and a false positive rate of 0.6% (1/174) which was significantly lower than that of 3.4% at the basal state (P < .05). In the screening for RVH, the criterion of a postcaptopril PRA of greater than 10.6 ng/mL/h had a false negative rate of 5.6% (1/18) and a false positive rate of 15.1% (26/172). This false positive rate was also significantly lower than that using a criterion for precaptopril PRA of 2.21 ng/mL/h (P < .05). Accordingly, the captopril test was a useful method in the simultaneous screening for PA and RVH, and it may be particularly applicable in specialized hypertension clinics.