Hypertension is a leading contributor to cardiovascular mortality worldwide. Despite this, its underlying mechanism(s) and the role of excess salt in cardiorenal dysfunction are unclear. Previously, we have identified cross-talk between mineralocorticoid receptor (MR), a nuclear transcription factor regulated by the steroid aldosterone, and the small GTPase Rac1, which is implicated in proteinuric kidney disease. We here show that high-salt loading activates Rac1 in the kidneys in rodent models of salt-sensitive hypertension, leading to blood pressure elevation and renal injury via an MR-dependent pathway. We found that a high-salt diet caused renal Rac1 upregulation in salt-sensitive Dahl (Dahl-S) rats and downregulation in salt-insensitive Dahl (Dahl-R) rats. Despite a reduction of serum aldosterone levels, salt-loaded Dahl-S rats showed increased MR signaling in the kidneys, and Rac1 inhibition prevented hypertension and renal damage with MR repression. We further demonstrated in aldosterone-infused rats as well as adrenalectomized Dahl-S rats with aldosterone supplementation that salt-induced Rac1 and aldosterone acted interdependently to cause MR overactivity and hypertension. Finally, we confirmed the key role of Rac1 in modulating salt susceptibility in mice lacking Rho GDP-dissociation inhibitor α. Therefore, our data identify Rac1 as a determinant of salt sensitivity and provide insights into the mechanism of salt-induced hypertension and kidney injury.

Background-Obesity is one of the major risk factors for cardiovascular disease and is often associated with increased oxidative stress and sympathoexcitation. We have already suggested that increased oxidative stress in the brain modulates the sympathetic regulation of arterial pressure in salt-sensitive hypertension, which is often associated with obesity. The present study was performed to determine whether oxidative stress could mediate central sympathoexcitation in the initial stage of obesity-induced hypertension. Methods and Results-Four-week-old male Sprague-Dawley rats were fed a high-fat (45% kcal as fat) or low-fat (10% kcal as fat) diet for 6 weeks. Fat loading elicited hypertension and sympathoexcitation, along with visceral obesity. In urethane-anesthetized and artificially ventilated rats, arterial pressure and renal sympathetic nerve activity decreased in a dose-dependent fashion when 53 or 105 mol/kg tempol, a membrane-permeable superoxide dismutase mimetic, was infused into the lateral cerebral ventricle. Central tempol reduced arterial pressure and renal sympathetic nerve activity to a significantly greater extent in high-fat diet-fed hypertensive rats than in low-fat diet-fed normotensive rats. Intracerebroventricular apocynin or diphenyleneiodonium, a reduced NADPH oxidase inhibitor, also elicited markedly greater reductions in arterial pressure and renal sympathetic nerve activity in the high-fat diet-fed rats. In addition, fat loading increased NADPH oxidase activity and NADPH oxidase subunit p22 phox , p47 phox , and gp91 phox mRNA expression in the hypothalamus. Key Words: brain Ⅲ hypertension Ⅲ obesity Ⅲ oxidative stress Ⅲ sympathetic nervous system M etabolic syndrome, a complex of highly debilitating disorders that consist of hypertension, diabetes mellitus, and dyslipidemia, is associated with the development of visceral obesity. 1 All of these features are risk factors for atherosclerosis; therefore, the metabolic syndrome results in a high incidence of cardiovascular events. Although hypertension is one of the major components of the metabolic syndrome, the mechanisms through which obesity contributes to hypertension have not been fully elucidated. Conclusions-In Clinical Perspective p 986Sympathetic activation is often associated with obesity. For example, studies using microneurography have consistently shown increased muscle sympathetic nerve activity in obese subjects. 2 Furthermore, muscle sympathetic nerve activity is closely associated with the level of abdominal visceral fat. 3 As expected, a number of studies indicated that sympathetic activation may be involved in obesity-induced hypertension. 4 In young, nondiabetic Japanese men, body mass index correlated with not only mean blood pressure but also pulse rate and plasma norepinephrine. 5 In an animal study, obese Zucker rats, which display hyperphagia-induced obesity caused by a mutation of the leptin receptor, have elevated sympathetic nerve activity and arterial pressure (AP). 6 Autonomic ganglionic blockade decreased m...

In recent years, a concept of renal rehabilitation has become widely known among nephrology specialists, dialysis specialists, kidney transplantation specialists, rehabilitation specialists, nutrition specialists, guideline specialists, nurses, physiotherapists, and representatives of patients. Therefore, in order to make it clear the definition, methods, and effectiveness of renal rehabilitation in Japan, we launched Renal Rehabilitation Guideline Preparation Committee in 2016 as a part of works in the Japanese Society of Renal Rehabilitation, and created a guideline in accordance to the "Minds Handbook for Clinical Practice Guideline Development 2014". Here, we report systematic reviews and recommendations of exercise therapies in patients with kidney diseases based on the guideline preparation committee works. Six recommendations for the condition of each kidney disorder, groups addressing nephritis/nephrosis, chronic kidney diseases, dialysis therapy, and kidney transplantation were created. All the recommendation grades were determined by a consensus conference participated in by representatives of patients and various professionals. The purpose of this report is to provide an evidence-based, best practice summary to optimize the quality, safety and efficacy, and availability of renal rehabilitation service, and to provide care for maximum patient prognosis, quality of life, and satisfaction.

Abstract-Metabolic syndrome is a highly predisposing condition for cardiovascular disease and could be a cause of excess salt-induced organ damage. Recently, several investigators have demonstrated that salt loading causes left ventricular diastolic dysfunction associated with increased oxidative stress and mineralocorticoid receptor activation. We, therefore, investigated whether excess salt induces cardiac diastolic dysfunction in metabolic syndrome via increased oxidative stress and upregulation of mineralocorticoid receptor signals. Thirteen-week-old spontaneously hypertensive rats and SHR/NDmcr-cps, the genetic model of metabolic syndrome, were fed a normal salt (0.5% NaCl) or high-salt (8% NaCl) diet for 4 weeks. In SHR/NDmcr-cps, salt loading induced severe hypertension, abnormal left ventricular relaxation, and perivascular fibrosis. Salt-loaded SHR/NDmcr-cps also exhibited overproduction of reactive oxygen species and upregulation of mineralocorticoid receptor-dependent gene expression, such as Na ϩ /H ϩ exchanger-1 and serumand glucocorticoid-inducible kinase-1 in the cardiac tissue. However, in spontaneously hypertensive rats, salt loading did not cause these cardiac abnormalities despite a similar increase in blood pressure. An antioxidant, tempol, prevented salt-induced diastolic dysfunction, perivascular fibrosis, and upregulation of mineralocorticoid receptor signals in SHR/NDmcr-cps. Moreover, a selective mineralocorticoid receptor antagonist, eplerenone, prevented not only diastolic dysfunction but also overproduction of reactive oxygen species in salt-loaded SHR/NDmcr-cps. These results suggest that metabolic syndrome is a predisposed condition for salt-induced left ventricular diastolic dysfunction, possibly via increased oxidative stress and enhanced mineralocorticoid receptor signals. which eventually leads to diastolic heart failure with a poor prognosis. 5,6 However, LV diastolic dysfunction has not always been seen in a MetS animal model. For example, in obesity-prone Sprague-Dawley rats, a moderate fat diet induced metabolic abnormalities but did not cause LV diastolic dysfunction. 7 This discrepancy indicates a possibility that some exogenous factors deteriorate cardiac function in MetS. In patients with MetS, high salt intake increased blood pressure (BP) greater than in those without MetS. 8 In an MetS rat model, evident renal injury was induced by salt loading. 9 These findings suggest that the MetS model is highly susceptible to salt-induced organ damage. Salt loading induced LV hypertrophy or LV diastolic dysfunction in several hypertension models. 10 -14 Therefore, it is speculated that LV diastolic impairment could be accelerated with excess salt in an MetS model.Reactive oxygen species (ROS) are important elements causing cardiac functional damage. 10,15,16 MetS should be associated with an increase in oxidative stress, 17-19 possibly through enhanced ROS-inducible adipocytokines. 20 -22 Also, salt loading increased oxidative stress in several salt-sensitive hypertension models...

Salt sensitivity of blood pressure (BP) is speculated to be a characteristic in obesity-induced hypertension. To elucidate the influence of obesity on salt-sensitive hypertension, we examined the effect of fat loading on BP, renal damage, and their progression induced by salt excess in Dahl salt-sensitive (S) rats. High fat (HF: 45% fat diet: 8 weeks) diet increased BP with greater weight gain and visceral fat accumulation than low fat (10% fat) diet. In HF-fed rats, plasma glucose, plasma insulin, and urinary catecholamine increased, and urinary protein tended to be elevated. Moreover, excessive salt (8% salt diet: 8 weeks)-induced hypertension and proteinuria was accelerated in HF-fed rats. Therefore, fat loading increased BP in Dahl S rats possibly through insulin-resistance and sympathetic excitation. Moreover, fat loading accelerated salt-induced BP elevation and renal damage, suggesting excessive intake of both fat and salt, such as a civilized diet, exert the synergic harmful effects.

Kawarazaki H, Ando K, Fujita M, Matsui H, Nagae A, Muraoka K, Kawarasaki C, Fujita T. Mineralocorticoid receptor activation: a major contributor to salt-induced renal injury and hypertension in young rats. Am J Physiol Renal Physiol 300: F1402-F1409, 2011. First published April 6, 2011 doi:10.1152/ajprenal.00691.2010.-Excessive salt intake is known to preferentially increase blood pressure (BP) and promote kidney damage in young, salt-sensitive hypertensive human and animal models. We have suggested that mineralocorticoid receptor (MR) activation plays a major role in kidney injury in young rats. BP and urinary protein were compared in young (3-wk-old) and adult (10-wk-old) uninephrectomized (UNx) Sprague-Dawley rats fed a high (8.0%)-salt diet for 4 wk. The effects of the MR blocker eplerenone on BP and renal injury were examined in the high-salt diet-fed young UNx rats. Renal expression of renin-angiotensinaldosterone (RAA) system components and of inflammatory and oxidative stress markers was also measured. The effects of the angiotensin receptor blocker olmesartan with or without low-dose aldosterone infusion, the aldosterone synthase inhibitor FAD286, and the antioxidant tempol were also studied. Excessive salt intake induced greater hypertension and proteinuria in young rats than in adult rats. The kidneys of young salt-loaded rats showed marked histological injury, overexpression of RAA system components, and an increase in inflammatory and oxidative stress markers. These changes were markedly ameliorated by eplerenone treatment. Olmesartan also ameliorated salt-induced renal injury but failed to do so when combined with low-dose aldosterone infusion. FAD286 and tempol also markedly reduced urinary protein. UNx rats exposed to excessive salt at a young age showed severe hypertension and renal injury, likely primarily due to MR activation and secondarily due to angiotensin receptor activation, which may be mediated by inflammation and oxidative stress. salt sensitivity; aldosterone; oxidative stress; renin-angiotensin OBSERVATIONAL STUDIES HAVE suggested that increased blood pressure (BP) in childhood correlates with increased BP in adulthood (36). Hypertension is closely related to kidney dysfunction, which can cause increased BP. Therefore, both BP control and maintenance of kidney health at a young age may be critical for BP management later in life.Salt consumption among very young children has increased in developed countries at a faster rate than in developing countries (9,28,33). It is believed that high salt (HS) intake during prepuberty contributes to high BP later in life (1, 23). In addition, increased BP resulting from excessive salt consumption has been shown to be enhanced in the young in several animal models of salt-sensitive (SS) hypertension (35). We previously demonstrated that in Dahl SS rats, an SS hypertension model, HS intake at a young age accelerates the development of kidney injury and hypertension (12). Interestingly, salt restriction during infant weaning has been reported to lo...

This multicentre, retrospective observational study was conducted from January 2010 to December 2010 to determine the optimal time for discontinuing continuous renal replacement therapy (CRRT) by evaluating factors predictive of successful discontinuation in patients with acute kidney injury. Analysis was performed for patients after CRRT was discontinued because of renal function recovery. Patients were divided into two groups according to the success or failure of CRRT discontinuation. In multivariate logistic regression analysis, urine output at discontinuation, creatinine level and CRRT duration were found to be significant variables (area under the receiver operating characteristic curve for urine output, 0.814). In conclusion, we found that higher urine output, lower creatinine and shorter CRRT duration were significant factors to predict successful discontinuation of CRRT.

It is intriguing that although FGF23 is not a causal factor for hypophosphatemia at 12 months post-transplantation, it is a significant predictor of this common complication.