The diagnostic dilemma of hypertensive nephrosclerosis: the nephrologist's view

A successful transfemoral transcatheter aortic valve replacement case with VIABAHN® VBX balloon-expandable stent-graft and long Dryseal sheath for challenging access route

Key Clinical Message

A combination of long large-bore sheath and balloon-expandable stent-graft can be effective to challenging access route in transfemoral transcatheter aortic valve replacement.

Abstract

An 88-year-old female with symptomatic severe aortic stenosis underwent transcatheter aortic valve replacement (TAVR). Multidetector computed tomography demonstrated a small aortic annulus, shaggy aorta, and significant stenosis with heavily calcified atherosclerotic lesions in the bilateral common iliac arteries (CIAs). TAVR with Evolut™ Pro+ via alternative approach was considered; however, our heart team concluded that the patient was unsuitable for the procedure due to anatomical reasons, patient frailty, and medication history. Finally, transfemoral TAVR with endovascular therapy (EVT) and 18Fr-65 cm-Dryseal was adopted for the site. Following EVT with VIABAHN® VBX balloon-expandable stent-graft (VBX) implantation to the right ostial CIA lesion, 18Fr-65 cm-Dryseal was advanced to the ascending aorta through VBX, and Evolut™ Pro+26 mm was successfully implanted without any complication. At the 2-month follow-up, the patient reported a significant improvement in shortness of breath and did not present any evidence of atheroembolism. Transfemoral TAVR with 18Fr-65 cm-Dryseal to shaggy aorta can be feasible depending on the plaque distribution, and VBX implantation to a heavily calcified ostial CIA lesion was safe and effective for obtaining enough lumen for a large-bore sheath.

Efficacy of LDL apheresis for the treatment of cholesterol crystal embolism: A prospective, controlled study

This study was performed to evaluate the efficacy and safety of LDL apheresis (LDL-A) for the treatment of cholesterol crystal embolism (CCE) after cardiovascular procedures. We conducted a prospective multicenter study of 34 patients with CCE and 15 historical control patients. The present participants underwent six sessions of LDL-A for 4 weeks and underwent medical therapy with corticosteroids and statins. The mean creatinine concentration and estimated glomerular filtration rate at baseline were 3.82 ± 2.29 mg/dL and 17.8 ± 9.9 mL/min/1.73 m² , respectively. The prevalence of maintenance dialysis at 24 weeks was significantly lower in the present participants than in the historical controls (3.1% vs. 40.0%, respectively; p < 0.0001), but the mortality rate at 24 weeks was comparable (19% vs. 33%, respectively). Although 45 adverse events occurred in 23 participants, there were no unexpected adverse events. LDL-A for CCE reduces the prevalence of maintenance dialysis 24 weeks later and is well tolerated. This study was registered in the Japan Registry of Clinical Trials (jRCTs022180029) and clinicaltrials.gov (NCT01726868).

Role of Inherited Thrombophilia Risk Factors in Patients with CKD-5 Receiving Haemodialysis

BACKGROUND

The inherited thrombophilic mutations of the factor V gene (FVG1691A Leiden-FVL), prothrombin gene (PTG20210A), and the methylenetetrahydrofolate reductase gene C677T (MTHFR C677T) are risk factors for thromboembolic events and are related to the pathogenesis of vascular diseases.

OBJECTIVES

The main objective of this study was to explore the role of these factors in the pathogenesis of chronic kidney disease (CKD) and survival of patients with CKD-5 receiving haemodialysis.

METHODS

A cohort of 395 patients with CKD-5 on haemodialysis, from 6 dialysis units in Crete, Greece were recruited based on their medical records and were followed for 5 years. We collected data on CKD-5 aetiology, thrombophilic gene expression, vascular access thrombosis, time of death, and causes of death.

RESULTS

The mutated genes just as prevalent in patients with CKD-5 as they were in a control group with no renal disease (p > 0.05). FVL heterozygosity was significantly more prevalent (11.4 vs. 5.7%; p = 0.036) in patients presented with CKD of unknown aetiology, compared to CKD secondary to known aetiologies. The survival of patients with CKD-5 receiving haemodialysis was not affected by the presence of any thrombophilic mutation. This held true for the whole cohort and for the cohort that included only lethal vascular events. Most patients with MTHFR C677T heterozygosity, and all patients with MTHFR C677T homozygosity, died from vascular events during the follow-up period.

CONCLUSION

The FVL mutation may act as a risk factor for CKD. This study increases our understanding of molecular mechanisms in the pathogenesis of CKD of unknown aetiology. Τhe presence of thrombophilic mutations did not affect the overall survival of patients with CKD-5. This finding probably reflects the effect of medical care on patient outcomes.

[Kidney disease care for the elderly]

In our aging population, kidney disease management needs to take into account the frailty of the elderly. Standardized geriatric assessments can be proposed to help clinicians apprehend this dimension in their daily practice. These tools allow to better identify frail patients and offer them more personalized and harmless treatments. This article aims to focus on the kidney diseases commonly observed in elderly patients and analyze their specific nephrogeriatric care modalities. It should be noticed that all known kidney diseases can be also observed in the elderly, most often with a quite similar clinical presentation. This review is thus focused on the diseases most frequently and most specifically observed in elderly patients (except for monoclonal gammopathy associated nephropathies, out of the scope of this work), as well as the peculiarities of old age nephrological care.

Cholesterol-embolization syndrome: current perspectives

Cholesterol-embolization syndrome (CES) is a multisystemic disease with various clinical manifestations. CES is caused by embolization of cholesterol crystals (CCs) from atherosclerotic plaques located in the major arteries, and is induced mostly iatrogenically by interventional and surgical procedures; however, it may also occur spontaneously. Embolized CCs lead to both ischemic and inflammatory damage to the target organ. Therefore, anti-inflammatory agents, such as corticosteroids and cyclophosphamide, have been investigated as treatment for CES in several studies, with conflicting results. Recent research has revealed that CES is actually a kind of autoinflammatory disease in which inflammasome pathways, such as NLRP3 and IL1, are induced by CCs. These recent findings may have clinical implications such that colchicine and IL1 inhibitors, namely canakinumab, may be beneficial in the early stages of CES.

Circulating miR-103a-3p contributes to angiotensin II-induced renal inflammation and fibrosis via a SNRK/NF-κB/p65 regulatory axis

Although angiotensin II (AngII) is known to cause renal injury and fibrosis, the underlying mechanisms remain poorly characterized. Here we show that hypertensive nephropathy (HN) patients and AngII-infused mice exhibit elevated levels of circulating miR103a-3p. We observe a positive correlation between miR-103a-3p levels and AngII-induced renal dysfunction. miR-103a-3p suppresses expression of the sucrose non-fermentable-related serine/threonine-protein kinase SNRK in glomerular endothelial cells, and glomeruli of HN patients and AngII-infused mice show reduced endothelial expression of SNRK. We find that SNRK exerts anti-inflammatory effects by interacting with activated nuclear factor-κB (NF-κB)/p65. Overall, we demonstrate that AngII increases circulating miR-103a-3p levels, which reduces SNRK levels in glomerular endothelial cells, resulting in the over-activation of NF-κB/p65 and, consequently, renal inflammation and fibrosis. Together, our work identifies miR-103a-3p/SNRK/NF-κB/p65 as a regulatory axis of AngII-induced renal inflammation and fibrosis.

Angiotensin II is known to cause renal inflammation and fibrosis. Here Lu et al. show that levels of circulating miR-103a-3p are elevated in hypertensive nephropathy patients and in an animal model of angiotensin II-induced renal dysfunction, and that miR-103a-3p suppresses SNRK expression leading to the activation of the pro-inflammatory NF-κB pathway in glomerular endothelial cells.

Patients with biopsy-proven nephrosclerosis and moderately impaired renal function have a higher risk for cardiovascular disease: 15 years' experience in a single, kidney disease center

BACKGROUND

Nephrosclerosis progresses slowly to end-stage renal disease (ESRD) in only a small percentage of patients. However, because hypertension and nephrosclerosis are normally found simultaneously, nephrosclerosis is a risk factor for cardiovascular disease (CVD). In turn, the onset of CVD may progress to further renal impairment.

AIM

To evaluate clinical outcomes and the association between nephrosclerosis and CVD in the long term.

DESIGN

Prospective study

METHODS

We prospectively assessed 35 patients (male/female: 19/16) with nephrosclerosis aged >30 years at disease onset, attending the Kidney Disease Center, Saitama Medical University, in a single teaching hospital center between 1995 and 2014. Nephrosclerosis was diagnosed in accordance with the criteria outlined in the World Health Organization (WHO) monograph of renal diseases. All patients were followed by means of registries for 10 years to record subsequent events, if any.

OUTCOMES

The primary study outcome was correlating the occurrence of CVD, defined as a composite of cardiovascular deaths, nonfatal and fatal myocardial infarction, and stroke, with the development of ESRD or death.

RESULTS

The mean age of patients at the time of biopsy was 54.8 ± 12.7 years (range 33-72 years). Of these patients, seven were affected by nonfatal CVD and two died due to CVD. Only one patient developed ESRD during the follow-up period. Using Kaplan-Meier analysis, risk factors for the primary study outcome were estimated to include an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2), systolic blood pressure > 130 mmHg and proteinuria > 1 g/g creatinine. Univariate analysis was used for the assessment of the relative risk for the primary study endpoint of several covariates: age, systolic blood pressure, eGFR and proteinuria at time of renal biopsy. eGFR was found to be the strongest factor determining an event-free period [relative risk (RR) =1.931, p = 0.014].

CONCLUSIONS

Patients with nephrosclerosis are at high risk of CVD when they have moderately advanced renal impairment.

Nephrosclerosis: update on a centenarian

Nephrosclerosis is an umbrella term defining changes in all compartments of the kidney, changes caused by hypertension and by ageing. Among other lesions, arteriolosclerosis and arteriolohyalinosis play a major role in inducing glomerular ischaemic shrinking and sclerosis along with glomerulomegaly and focal-segmental glomerulosclerosis (FSGS). These lesions are accompanied by tubulointerstitial inflammation and fibrosis that predict the decline of renal function. Nephrosclerosis is a major cause of renal insufficiency in blacks of African descent with a severe, early form of renovasculopathy and a rapid course to renal failure with predominant lesions of FSGS. It seems that in blacks, separate genetic factors independently lead to vascular lesions and to hypertension with a different time-scale of their onset and of their progression, nephroangiosclerosis preceding the onset of hypertension. Conversely, true and histologically identified nephrosclerosis in white Europeans rarely leads to end-stage renal disease in the absence of malignant hypertension. Various animal models demonstrate that renal vascular lesions may exist in the absence of hypertension. These experiments also point to a major role of angiotensin II and of a number of independent and overlapping cellular and molecular pathways in a cascade of inflammatory events that end in renal fibrosis. Two pathophysiologic mechanisms are at work in inducing glomerular lesions and tubulointerstitial fibrosis: a loss of autoregulation of the renal blood flow caused by an arteriolohyalinosis of the glomerular afferent arteriole and ischaemia that fosters the generation of hypoxia inducible-fibrosing factors. Not all antihypertensive drugs equally protect the kidney from nephrosclerosis. Angiotensin II antagonists exert a favourable effect on hyperfiltration. Conversely, dihydropyridine calcium-channel blockers and vasodilators do not withstand the derangement of renal autoregulation.

ACR Appropriateness Criteria(®) on renal failure

Imaging plays a role in the management of patients with acute kidney injury or chronic kidney disease. However, clinical circumstances strongly impact the appropriateness of imaging use. In patients with newly detected renal dysfunction, ultrasonography can assess for reversible causes, assess renal size and echogenicity, and thus, establish the chronicity of disease. Urinary obstruction can be detected, but imaging is most useful in high-risk groups or in patients in whom there is a strong clinical suspicion for obstruction. Computed tomography, computed tomography or magnetic resonance arteriography, and percutaneous ultrasound-guided renal biopsy are valuable in other clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Atheroembolic renal disease with rapid progression and fatal outcome

Atheroembolic renal disease is caused by foreign-body reaction to cholesterol crystals flushed from the atherosclerotic plaques into the small-vessel system of the kidneys. It is an underdiagnosed entity, mostly related to vascular procedures and/or anticoagulation, and prognosis is considered to be poor. Besides the benefit of aggressive medical prevention of further embolic events, use of steroid therapy has been associated with greater survival. Here we report a case of a patient with a multisystemic presentation of the disease days after performance of percutaneous coronary intervention and anticoagulation initiation due to an episode of myocardial infarction. Renal, cutaneous, ophthalmic, neurological, and possibly muscular and mesenteric involvement was diagnosed. Although medical treatment with corticosteroids and avoidance of further anticoagulation was applied, the patient rapidly progressed to end-stage renal disease requiring hemodialysis and died 6 months after diagnosis. This is a case of catastrophic progression of the disease resistant to therapeutic measures. Focus on diagnosis and more efficient preventive and therapeutic protocols are therefore needed.

Atheroembolic renal disease

Atheroembolic renal disease develops when atheromatous aortic plaques rupture, releasing cholesterol crystals into the small renal arteries. Embolisation often affects other organs, such as the skin, gastrointestinal system, and brain. Although the disease can develop spontaneously, it usually develops after vascular surgery, catheterisation, or anticoagulation. The systemic nature of atheroembolism makes diagnosis difficult. The classic triad of a precipitating event, acute or subacute renal failure, and skin lesions, are strongly suggestive of the disorder. Eosinophilia further supports the diagnosis, usually confirmed by biopsy of an affected organ or by the fundoscopic finding of cholesterol crystals in the retinal circulation. Renal and patient prognosis are poor. Treatment is mostly preventive, based on avoidance of further precipitating factors, and symptomatic, aimed to the optimum treatment of hypertension and cardiac and renal failure. Statins, which stabilise atherosclerotic plaques, should be offered to all patients. Steroids might have a role in acute or subacute progressive forms with systemic inflammation.

Diabetic nephropathy in the elderly

Renal impairment is frequent in aged diabetic patients, notably with type 2 diabetes. It results from a multifactorial pathogeny, particularly the combined actions of hyperglycaemia, arterial hypertension and ageing. Diabetic nephropathy (DN) is associated with an increased cardiovascular mortality. DN often leads to end stage renal failure (ESRF) which causes specific problems of decision and practical organization of extra-renal epuration in diabetic and aged patients. In the absence of renal biopsy, clinical signs are often insufficient to assess the diabetic origin of a nephropathy in an elderly diabetic patient. Prevention of DN is principally based on tight glycaemic and blood pressure control. The progression of renal lesions can be retarded by strict blood pressure control, notably by blocking of the renin-angiotensin system, if well tolerated in aged patients. It is absolutely necessary to avoid the worsening of renal lesions by potentially nephrotoxic products, notably non steroidal anti-inflammatory drugs (NSAIDs) and iodinated contrast media. At the stage of renal failure, it is important to adapt the antidiabetic treatment, and in the majority of the cases, to switch to insulin when glomerular filtration rate (GFR) is below 30 ml/mn/1.73 m2.

The Enigma of Hypertensive ESRD: Observations on Incidence and Trends in 18 European, Canadian, and Asian-Pacific Populations, 1998 to 2002

BACKGROUND

Despite improved treatment of hypertension and decreasing rates of stroke and coronary heart disease, the reported incidence of hypertensive end-stage renal disease (ESRD) increased during the 1990s. However, bias, particularly from variations in acceptance into ESRD treatment (ascertainment) and diagnosis (classification), has been a major source of error when comparing ESRD incidences or estimating trends.

METHODS

Age-standardized rates were calculated in persons aged 30 to 44, 45 to 64, and 65 to 74 years for 15 countries or regions (separately for the Europid and non-Europid populations of Canada, Australia, and New Zealand), and temporal trends were estimated by means of Poisson regression. For 10 countries or regions, population-based estimates of mean systolic blood pressures and prevalences of hypertension were extracted from published sources.

RESULTS

Hypertensive ESRD, comprising ESRD attributed to essential hypertension or renal artery occlusion, was least common in Finland, non-Aboriginal Australians, and non-Polynesian New Zealanders; intermediate in most European and Canadian populations; and most common in Aboriginal Australians and New Zealand Maori and Pacific Island people. Rates correlated with the incidence of all other nondiabetic ESRD, but not with diabetic ESRD or community rates of hypertension. Between 1998 and 2002, hypertensive ESRD did not increase in Northwestern Europe or non-Aboriginal Canadians, although it did so in Australia.

CONCLUSION

Despite the likelihood of classification bias, the probability remains of significant variation in incidence of hypertensive ESRD within the group of Europid populations. These between-population differences are not explained by community rates of hypertension or ascertainment bias.

Cholesterol crystal embolism: diagnosis and treatment

Cholesterol crystal embolization (CCE) is a dreaded complication of radiology, vascular surgery, and/or anticoagulation in patients with atherosclerosis and ulcerated aortic plaques. It also represents a cause of early graft failure and of poor results of renal artery surgery. Crystals lodge in small caliber renal arteries, where they induce early, transitory thrombosis followed by delayed, definitive obstruction by endarteritis, accompanied by evidence of inflammation and eosinophilia. Massive CCE leads to early oligoanuria. In subacute forms, renal insufficiency is often delayed by weeks or months following the triggering event. A third, chronic subset of CCE is easily mistaken for atherosclerotic renal ischemia and/or nephrosclerosis. The kidney is rarely the sole organ involved in acute/subacute forms, in which the central nervous system, the coronary arteries, the spinal cord, and the mesenteric and pancreatic blood supply compromise represent the main causes of death. Cutaneous, retinal, and muscle involvement allow diagnosis by inspection or scarcely invasive biopsies in about 80% of cases, whereas renal biopsy as the only diagnostic procedure is required in 20% of cases. Prevention is based on avoidance of endovascular radiology maneuvers, vascular surgery, and excess anticoagulation in atherosclerotic patients. Treatment of acute/subacute forms of renal insufficiency consisting of stopping anticoagulation and forbidding any new radiologic and/or vascular surgery procedure; treating hypertension with angiotensin 2 antagonists and vasodilators, strict volemic control by loop diuretics and ultrafiltration, along with parenteral nutrition and prednisone, has been credited with improved outcome. Iloprost may obtain favorable results. Statins definitely ameliorate the renal and patient's prognosis.

[Atherosclerosis and the kidney]

Diffuse atherosclerosis entails a 15-30% risk of plaques on renal arteries (ARAS), with a correlation with coronary atherosclerosis. Ischemia induces generation of angiotensin II (Ang II) that maintains sufficient hydrostatic pressure within the tuft to preserve the GFR. Ang II inhibition suppresses this protective mechanism. In fact, any antihypertensive drug may lead to reaching a "critical perfusion pressure". ARAS should be suspected in case of renal asymmetry. It should also be envisaged in case of "flash pulmonary edemas". Ultrasonography and renal tomography show aortic calcifications and often the outline of an abdominal aortic aneurysm. Tomodensitometry may detect large aorto-renal plaques. Spiral scanner tomography represents a progress, in terms of renal artery imaging and of renal cortical atrophy. Magnetic resonance imaging is less accurate but avoids iodine toxicity. The best noninvasive method is pulsed echo-doppler. It is particularly useful for evaluating stenoses progression. Some stenoses progress to renal atrophy and renal artery thrombosis, whereas others follow a stable course. Pulsed Doppler helps predict whether revascularization will improve renal function, according to the resistance index. Renal arteriography entails a high risk of cholesterol crystal embolism. However, it is the obligatory first step for angioplasty and stent positioning, indicated when the kidney is not atrophic. The indication for revascularization essentially depends on evaluation of the benefits vs risks of angioplasty or surgery. Some publications underscore the frequent stability of renal function and the fact that, revascularized or not, most patients will shortly die of myocardial infarction. Renal cholesterol crystal embolism (CCE) is a severe condition, which occurs when large arteries undergo surgery, aortography or interventional radiology. Anticoagulants are a frequent cause of CCE. CCE may also occur spontaneously, resulting in slowly progressive renal insufficiency. Migration of crystals in small caliber intrarenal arteries induces obstruction, followed by an inflammatory reaction. The clinical picture resembles angiitis, with laboratory evidence of inflammation along with high eosinophil counts and hypocomplementemia. Diagnosis rests on: 1) a iatrogenic event in a patient with an atherosclerotic background; 2) examination of the skin disclosing purple toes, small necrotic lesions and livedo of the lower limbs. Crystals may also be found by funduscopy. Skin or muscle biopsy are contributive in showing crystals and help avoid renal biopsy; 3) other localizations involve the mesenteric circulation and the central nervous system. Until recently, the prognosis was considered disastrous. However, a recently published treatment schedule proved efficient in reducing mortality. A last issue regarding the relationships between atherosclerosis and the kidney deserves mention. In an autopsy-based study it was shown that atherosclerosis per se is accompanied by an increase in the glomerular surface area along with a greater proportion of obsolescent glomeruli by comparison with matched controls. Finally, it should be recalled that atherogenic hyperlipidemia usually aggravates the course of any renal disease, including ARAS. Treatment with statins is indicated in all forms of atherosclerotic renal disease.

Aldosterone and the hypertensive kidney: its emerging role as a mediator of progressive renal dysfunction: a paradigm shift

End-stage renal disease (ESRD) comprises an enormous public health burden, with an increasing incidence and prevalence. Hypertension is a major risk factor for progressive renal disease. This escalating prevalence suggests that newer therapeutic interventions and strategies are needed to complement current antihypertensive approaches. Although much evidence demonstrates that angiotensin II mediates progressive renal disease, recent evidence also implicates aldosterone as an important pathogenetic factor in progressive renal disease. Several lines of experimental evidence demonstrate that selective blockade of aldosterone, independent of renin-angiotensin blockade, reduces proteinuria and nephrosclerosis in the spontaneously hypertensive stroke-prone rat model and reduces proteinuria and glomerulosclerosis in the subtotally nephrectomized rat model (i.e. remnant kidney). Whereas pharmacological blockade with angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors reduces proteinuria and nephrosclerosis/ glomerulosclerosis, selective reinfusion of aldosterone restores these abnormalities despite continued renin-angiotensin blockade. Aldosterone may promote fibrosis by several mechanisms, including plasminogen activator inhibitor-1 expression and consequent alterations of vascular fibrinolysis, by stimulation of transforming growth factor-beta 1, and by stimulation of reactive oxygen species. Based on this theoretical construct, randomized clinical studies will be initiated to delineate the potential renal-protective effects of antihypertensive therapy utilizing aldosterone receptor blockade.

History of hypertension in patients treated for end-stage renal disease

OBJECTIVES

To describe patterns of hypertension history in patients with various types of end-stage renal disease (ESRD) and in persons with normal kidney function; and to identify risk factors for the diagnosis 'hypertensive ESRD'.

DESIGN

A case-control study.

SETTING

Population-based.

PARTICIPANTS

Patients with ESRD due to hypertension (n = 214), diabetes (n = 239), other specified causes (n = 181), unknown causes (n = 82) and control subjects drawn from the general population (n = 361).

MAIN OUTCOME MEASURES

Participants' history of hypertension.

RESULTS

The prevalence of hypertension was 90% in ESRD patients and 27% in controls. Only 6% of patients with hypertensive ESRD had a history of malignant hypertension. Patients with hypertensive ESRD were more likely to have been hospitalized because of hypertension (36%) than were other ESRD patients (18%) or controls (5%). ESRD of any cause was more strongly associated with hypertension of > or = 25 years duration (odds ratio 51.0, compared with normal blood pressure) than it was with hypertension of shorter duration (15-25 years: odds ratio 31.8, 5-15 years: odds ratio 16.0, < 5 years: odds ratio 21.2). Among patients who had both hypertension and ESRD, the diagnosis of 'hypertensive ESRD' was associated independently with a long duration of hypertension, greater severity of hypertension, the absence of diabetes, black race, and limited education.

CONCLUSIONS

Hypertension is common among patients with ESRD. The risk of ESRD from any cause increases progressively with the duration of hypertension, and with indicators of severe hypertension. This result supports the hypothesis that nonmalignant hypertension of long duration may cause renal insufficiency. The criteria used to diagnose hypertensive ESRD are consistent with pathophysiologic and epidemiologic evidence.

Effect of 2,3-dimercaptosuccinic acid on nephrosclerosis in the Dahl rat. I. Role of reactive oxygen species

2,3-Dimercaptosuccinic acid (DMSA), a sulfhydryl-containing chelator, has previously been shown to reduce mean blood pressure in lead-treated rats. In the present study we have demonstrated that DMSA (0.5% for 5 days every 2 weeks) also reduces mean blood pressure in the Dahl salt-sensitive (SS) rat. Six-week-old Dahl SS and salt resistant (SR) rats were placed on a 0.3% NaCl diet for two weeks, followed by an 8% NaCl diet for four weeks. Eight SS and 8 SR rats remained untreated while 8 SS and 8 SR rats were treated with DMSA. DMSA treatment ameliorated the mean blood pressure rise in the Dahl SS rats (141 +/- 5 vs. 120 +/- 4 mm Hg at 6 weeks, P < 0.001). Nephrosclerosis was severe in untreated SS rats but absent in treated SS rats as well as in both treated and untreated SR rats. Reactive oxygen species formation, as assessed by kidney cortex content of malondialdehyde (MDA) and immunohistochemical demonstration of nitrotyrosine (a byproduct of peroxynitrite) in interlobular arteries, was increased in Dahl SS rats, but abolished by DMSA (MDA 9.65 +/- 0.33 nmol/g wet wt, untreated SS, vs. 6.46 +/- 0.51, treated SS, P < 0.001). The anti-nephrosclerotic action of DMSA was clearly disproportionate to the reduction in blood pressure. We conclude that the effect of DMSA was related instead to the reactive oxygen species scavenging properties of the thiol groups.