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Background: Statin therapy is effective for the prevention of atherosclerotic cardiovascular disease and is widely prescribed, but there are persisting concerns that statin therapy might frequently cause muscle pain or weakness. We aimed to address these through an individual participant data meta-analysis of all recorded adverse muscle events in large, long-term, randomised, double-blind trials of statin therapy. Methods: Randomised trials of statin therapy were eligible if they aimed to recruit at least 1000 participants with a scheduled treatment duration of at least 2 years, and involved a double-blind comparison of statin versus placebo or of a more intensive versus a less intensive statin regimen. We analysed individual participant data from 19 double-blind trials of statin versus placebo (n=123 940) and four double-blind trials of a more intensive versus a less intensive statin regimen (n=30 724). Standard inverse-variance-weighted meta-analyses of the effects on muscle outcomes were conducted according to a prespecified protocol. Findings: Among 19 placebo-controlled trials (mean age 63 years [SD 8], with 34 533 [27·9%] women, 59 610 [48·1%] participants with previous vascular disease, and 22 925 [18·5%] participants with diabetes), during a weighted average median follow-up of 4·3 years, 16 835 (27·1%) allocated statin versus 16 446 (26·6%) allocated placebo reported muscle pain or weakness (rate ratio [RR] 1·03; 95% CI 1·01–1·06). During year 1, statin therapy produced a 7% relative increase in muscle pain or weakness (1·07; 1·04–1·10), corresponding to an absolute excess rate of 11 (6–16) events per 1000 person-years, which indicates that only one in 15 ([1·07–1·00]/1·07) of these muscle-related reports by participants allocated to statin therapy were actually due to the statin. After year 1, there was no significant excess in first reports of muscle pain or weakness (0·99; 0·96–1·02). For all years combined, more intensive statin regimens (ie, 40–80 mg atorvastatin or 20–40 mg rosuvastatin once per day) yielded a higher RR than less intensive or moderate-intensity regimens (1·08 [1·04–1·13] vs 1·03 [1·00–1·05]) compared with placebo, and a small excess was present (1·05 [0·99–1·12]) for more intensive regimens after year 1. There was no clear evidence that the RR differed for different statins, or in different clinical circumstances. Statin therapy yielded a small, clinically insignificant increase in median creatine kinase values of approximately 0·02 times the upper limit of normal. Interpretation: Statin therapy caused a small excess of mostly mild muscle pain. Most (>90%) of all reports of muscle symptoms by participants allocated statin therapy were not due to the statin. The small risks of muscle symptoms are much lower than the known cardiovascular benefits. There is a need to review the clinical management of muscle symptoms in patients taking a statin. Funding: British Heart Foundation, Medical Research Council, Australian National Health and Medical Research Council.

This study shows that aquaporin-2 regulation is disrupted by a small fall in plasma potassium levels and the response is influenced by sexual dimorphism in renal potassium handling. The findings provided new insights into the mechanisms by which water balance is altered in dietary potassium deficiency and support defining the disorder as “potassium-dependent nephrogenic diabetes insipidus.”

The association between diabetes insipidus (DI) and chronic dietary K(+) deprivation is well known, but it remains uncertain how the disorder develops and whether it is influenced by the sexual dimorphism in K(+) handling. Here, we determined the plasma K(+) (P(K)) threshold for DI in male and female mice and ascertained if DI is initiated by polydipsia or by a central or nephrogenic defect. C57BL6J mice were randomized to a control diet or to graded reductions in dietary K(+) for 8 days, and kidney function and transporters involved in water balance were characterized. We found that male and female mice develop polyuria and secondary polydipsia. Altered water balance coincided with a decrease in aquaporin-2 (AQP2) phosphorylation and apical localization despite increased levels of the vasopressin surrogate marker copeptin. No change in the protein abundance of urea transporter-A1 was observed. The Na(+)-K(+)-2Cl(−) cotransporter decreased only in males. Desmopressin treatment failed to reverse water diuresis in K(+)-restricted mice. These findings indicate that even a small fall in P(K) is associated with nephrogenic DI (NDI), coincident with the development of altered AQP2 regulation, implicating low P(K) as a causal trigger of NDI. We found that P(K) decreased more in females, and, consequently, females were more prone to develop NDI. Together, these data indicate that AQP2 regulation is disrupted by a small decrease in P(K) and that the response is influenced by sexual dimorphism in K(+) handling. These findings provide new insights into the mechanisms linking water and K(+) balances and support defining the disorder as “potassium-dependent NDI.” NEW & NOTEWORTHY This study shows that aquaporin-2 regulation is disrupted by a small fall in plasma potassium levels and the response is influenced by sexual dimorphism in renal potassium handling. The findings provided new insights into the mechanisms by which water balance is altered in dietary potassium deficiency and support defining the disorder as “potassium-dependent nephrogenic diabetes insipidus.”

BACKGROUND: In the primary analysis of the Aspirin in Reducing Events in the Elderly (ASPREE) trial, now published in the Journal, we report that the daily use of aspirin did not provide a benefit with regard to the primary end point of disability-free survival among older adults. A numerically higher rate of the secondary end point of death from any cause was observed with aspirin than with placebo. METHODS: From 2010 through 2014, we enrolled community-dwelling persons in Australia and the United States who were 70 years of age or older (or ≥65 years of age among blacks and Hispanics in the United States) and did not have cardiovascular disease, dementia, or disability. Participants were randomly assigned to receive 100 mg of enteric-coated aspirin or placebo. Deaths were classified according to the underlying cause by adjudicators who were unaware of trial-group assignments. Hazard ratios were calculated to compare mortality between the aspirin group and the placebo group, and post hoc exploratory analyses of specific causes of death were performed. RESULTS: Of the 19,114 persons who were enrolled, 9525 were assigned to receive aspirin and 9589 to receive placebo. A total of 1052 deaths occurred during a median of 4.7 years of follow-up. The risk of death from any cause was 12.7 events per 1000 person-years in the aspirin group and 11.1 events per 1000 person-years in the placebo group (hazard ratio, 1.14; 95% confidence interval [CI], 1.01 to 1.29). Cancer was the major contributor to the higher mortality in the aspirin group, accounting for 1.6 excess deaths per 1000 person-years. Cancer-related death occurred in 3.1% of the participants in the aspirin group and in 2.3% of those in the placebo group (hazard ratio, 1.31; 95% CI, 1.10 to 1.56). CONCLUSIONS: Higher all-cause mortality was observed among apparently healthy older adults who received daily aspirin than among those who received placebo and was attributed primarily to cancer-related death. In the context of previous studies, this result was unexpected and should be interpreted with caution. (Funded by the National Institute on Aging and others; ASPREE ClinicalTrials.gov number, NCT01038583.)

BACKGROUND: Information on the use of aspirin to increase healthy independent life span in older persons is limited. Whether 5 years of daily low-dose aspirin therapy would extend disability-free life in healthy seniors is unclear. METHODS: From 2010 through 2014, we enrolled community-dwelling persons in Australia and the United States who were 70 years of age or older (or ≥65 years of age among blacks and Hispanics in the United States) and did not have cardiovascular disease, dementia, or physical disability. Participants were randomly assigned to receive 100 mg per day of enteric-coated aspirin or placebo orally. The primary end point was a composite of death, dementia, or persistent physical disability. Secondary end points reported in this article included the individual components of the primary end point and major hemorrhage. RESULTS: A total of 19,114 persons with a median age of 74 years were enrolled, of whom 9525 were randomly assigned to receive aspirin and 9589 to receive placebo. A total of 56.4% of the participants were women, 8.7% were nonwhite, and 11.0% reported previous regular aspirin use. The trial was terminated at a median of 4.7 years of follow-up after a determination was made that there would be no benefit with continued aspirin use with regard to the primary end point. The rate of the composite of death, dementia, or persistent physical disability was 21.5 events per 1000 person-years in the aspirin group and 21.2 per 1000 person-years in the placebo group (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11; P=0.79). The rate of adherence to the assigned intervention was 62.1% in the aspirin group and 64.1% in the placebo group in the final year of trial participation. Differences between the aspirin group and the placebo group were not substantial with regard to the secondary individual end points of death from any cause (12.7 events per 1000 person-years in the aspirin group and 11.1 events per 1000 person-years in the placebo group), dementia, or persistent physical disability. The rate of major hemorrhage was higher in the aspirin group than in the placebo group (3.8% vs. 2.8%; hazard ratio, 1.38; 95% CI, 1.18 to 1.62; P

Markers of inflammation, including plasma C-reactive protein (CRP), are associated with an increased risk of cardiovascular disease, and it has been suggested that this association is causal. However, the relationship between inflammation and cardiovascular disease has not been extensively studied in patients with chronic kidney disease. To evaluate this, we used data from the Study of Heart and Renal Protection (SHARP) to assess associations between circulating CRP and LDL cholesterol levels and the risk of vascular and non-vascular outcomes. Major vascular events were defined as nonfatal myocardial infarction, cardiac death, stroke or arterial revascularization, with an expanded outcome of vascular events of any type. Higher baseline CRP was associated with an increased risk of major vascular events (hazard ratio per 3x increase 1.28; 95% confidence interval 1.19-1.38). Higher baseline LDL cholesterol was also associated with an increased risk of major vascular events (hazard ratio per 0.6 mmol/L higher LDL cholesterol; 1.14, 1.06-1.22). Higher baseline CRP was associated with an increased risk of a range of non-vascular events (1.16, 1.12-1.21), but there was a weak inverse association between baseline LDL cholesterol and non-vascular events (0.96, 0.92-0.99). The efficacy of lowering LDL cholesterol with simvastatin/ezetimibe on major vascular events, in the randomized comparison, was similar irrespective of CRP concentration at baseline. Thus, decisions to offer statin-based therapy to patients with chronic kidney disease should continue to be guided by their absolute risk of atherosclerotic events. Estimation of such risk may include plasma biomarkers of inflammation, but there is no evidence that the relative beneficial effects of reducing LDL cholesterol depends on plasma CRP concentration.

BACKGROUND Dobutamine stress echocardiography (DSE) is commonly used for cardiovascular assessment before orthotopic liver transplantation (OLT). The coronary artery calcium score (CACS) is a useful screening tool for coronary artery disease (CAD). We aimed to compare the sensitivity and specificity of DSE and CACS for CAD in OLT candidates. MATERIAL AND METHODS A total of 265 of the 1589 patients who underwent OLT at our center between 2008 and 2019 had preoperative coronary angiography (CAG). Of these, 173 had DSE and 133 had a CT scan suitable for CACS calculation within 1 year of OLT. Patients with a nondiagnostic DSE were excluded (n=100). Two reviewers evaluated CACS on CT scans. The sensitivity/specificity of DSE and CACS for detection of angiographically significant CAD were calculated for patients with both tests (n=36). A separate analysis compared the sensitivity/specificity of a diagnostic DSE (n=73) and CACS (n=133) against CAG for all patients with either test. RESULTS Sensitivity and specificity were 57.1% and 89.7%, respectively, for DSE, compared with 71.4% and 62.1% for CACS at ≥100 Agatston score. For the analysis of all patients with either test, the sensitivity/specificity of DSE for detection of CAD and CACS were 30.8% and 85.0% and 80.0% and 62.8%, respectively. On ROC analysis, CACS was a satisfactory predictor of obstructive CAD (AUC, 0.76±0.06, 95% CI, 0.66-0.87; P0.001). CONCLUSIONS CACS may be an important tool for cardiovascular assessment in patients undergoing OLT. DSE was nondiagnostic in a large percentage of OLT candidates, limiting its use in this population.

Background Hyperkalemia in association with metabolic acidosis that are out of proportion to changes in glomerular filtration rate defines type 4 renal tubular acidosis (RTA), the most common RTA observed, but the molecular mechanisms underlying the associated metabolic acidosis are incompletely understood. We sought to determine whether hyperkalemia directly causes metabolic acidosis and, if so, the mechanisms through which this occurs. Methods We studied a genetic model of hyperkalemia that results from early distal convoluted tubule (DCT)–specific overexpression of constitutively active Ste20/SPS1-related proline-alanine–rich kinase (DCT-CA-SPAK). Results DCT-CA-SPAK mice developed hyperkalemia in association with metabolic acidosis and suppressed ammonia excretion; however, titratable acid excretion and urine pH were unchanged compared with those in wild-type mice. Abnormal ammonia excretion in DCT-CA-SPAK mice associated with decreased proximal tubule expression of the ammonia-generating enzymes phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase and overexpression of the ammonia-recycling enzyme glutamine synthetase. These mice also had decreased expression of the ammonia transporter family member Rhcg and decreased apical polarization of H(+)-ATPase in the inner stripe of the outer medullary collecting duct. Correcting the hyperkalemia by treatment with hydrochlorothiazide corrected the metabolic acidosis, increased ammonia excretion, and normalized ammoniagenic enzyme and Rhcg expression in DCT-CA-SPAK mice. In wild-type mice, induction of hyperkalemia by administration of the epithelial sodium channel blocker benzamil caused hyperkalemia and suppressed ammonia excretion. Conclusions Hyperkalemia decreases proximal tubule ammonia generation and collecting duct ammonia transport, leading to impaired ammonia excretion that causes metabolic acidosis.

Aberrant activation of with no lysine (WNK) kinases causes familial hyperkalemic hypertension (FHHt). Thiazide diuretics treat the disease, fostering the view that hyperactivation of the thiazide-sensitive sodium-chloride cotransporter (NCC) in the distal convoluted tubule (DCT) is solely responsible. However, aberrant signaling in the aldosterone-sensitive distal nephron (ASDN) and inhibition of the potassium-excretory renal outer medullary potassium (ROMK) channel have also been implicated. To test these ideas, we introduced kinase-activating mutations after Lox-P sites in the mouse Stk39 gene, which encodes the terminal kinase in the WNK signaling pathway, Ste20-related proline-alanine-rich kinase (SPAK). Renal expression of the constitutively active (CA)-SPAK mutant was specifically targeted to the early DCT using a DCT-driven Cre recombinase. CA-SPAK mice displayed thiazide-treatable hypertension and hyperkalemia, concurrent with NCC hyperphosphorylation. However, thiazide-mediated inhibition of NCC and consequent restoration of sodium excretion did not immediately restore urinary potassium excretion in CA-SPAK mice. Notably, CA-SPAK mice exhibited ASDN remodeling, involving a reduction in connecting tubule mass and attenuation of epithelial sodium channel (ENaC) and ROMK expression and apical localization. Blocking hyperactive NCC in the DCT gradually restored ASDN structure and ENaC and ROMK expression, concurrent with the restoration of urinary potassium excretion. These findings verify that NCC hyperactivity underlies FHHt but also reveal that NCC-dependent changes in the driving force for potassium secretion are not sufficient to explain hyperkalemia. Instead, a DCT-ASDN coupling process controls potassium balance in health and becomes aberrantly activated in FHHt.

Reverse Remodeling Survival CRTBackground Multiple definitions of reverse ventricular remodeling (RVR) employing various changes in left ventricular end-systolic (LVESV) or diastolic volumes (LVEDVs) or left ventricular ejection fraction (LVEF) have been used in determining cardiac resynchronization therapy (CRT) response, making comparability across studies difficult. We compared different metrics to each other, and in combination, in terms of association with long-term outcomes. Methods We collected clinical and echocardiographic data on 436 patients undergoing CRT. LVEF was assessed via a combined volumetric and visual assessment. Volumes were manually traced. Using a nested multivariate model of a priori determined predictors of long-term survival free of left ventricular assist device (LVAD) or heart transplant, multiple definitions of RVR were added to the model individually to determine which provided the best model fit. Results Over a mean follow-up of 5.4 ± 2.3 years, there were 198 endpoints (10 LVADs, 15 heart transplants, and 173 deaths). When added to a nested model controlling for multiple potential confounders, all definitions of RVR were significantly associated with improved survival. Changes in LVEF and LVESV were superior to changes in LVEDV. A combination metric of an LVEF improvement ≥ 5% and LVESV reduction ≥ 10% was the best overall metric for model fit. Conclusions Changes in LVESV and LVEF are better predictors of long-term outcome following CRT compared to changes in LVEDV. Adding an assessment of LVEF to reduction in LVESV ≥ 10% provided the best overall definition for RVR in predicting CRT outcomes.

International audience; Gain-of-function mutations in with no lysine (K) 1 (WNK1) and WNK4 genes are responsible for familial hyperkalemic hypertension (FHHt), a rare, inherited disorder characterized by arterial hypertension and hyperkalemia with metabolic acidosis. More recently, FHHt-causing mutations in the Kelch-like 3-Cullin 3 (KLHL3-CUL3) E3 ubiquitin ligase complex have shed light on the importance of WNK's cellular degradation on renal ion transport. Using full exome sequencing for a 4-generation family and then targeted sequencing in other suspected cases, we have identified new missense variants in the WNK1 gene clustering in the short conserved acidic motif known to interact with the KLHL3-CUL3 ubiquitin complex. Affected subjects had an early onset of a hyperkalemic hyperchloremic phenotype, but normal blood pressure values"Functional experiments in Xenopus laevis oocytes and HEK293T cells demonstrated that these mutations strongly decrease the ubiquitination of the kidney-specific isoform KS-WNK1 by the KLHL3-CUL3 complex rather than the long ubiquitous catalytically active L-WNK1 isoform. A corresponding CRISPR/Cas9 engineered mouse model recapitulated both the clinical and biological phenotypes. Renal investigations showed increased activation of the Ste20 proline alanine-rich kinase-Na+-Cl- cotransporter (SPAK-NCC) phosphorylation cascade, associated with impaired ROMK apical expression in the distal part of the renal tubule. Together, these new WNK1 genetic variants highlight the importance of the KS-WNK1 isoform abundance on potassium homeostasis.

Lowering LDL cholesterol reduces the risk of developing atherosclerotic events in CKD, but the effects of such treatment on progression of kidney disease remain uncertain. Here, 6245 participants with CKD (not on dialysis) were randomly assigned to simvastatin (20 mg) plus ezetimibe (10 mg) daily or matching placebo. The main prespecified renal outcome was ESRD (defined as the initiation of maintenance dialysis or kidney transplantation). During 4.8 years of follow-up, allocation to simvastatin plus ezetimibe resulted in an average LDL cholesterol difference (SEM) of 0.96 (0.02) mmol/L compared with placebo. There was a nonsignificant 3% reduction in the incidence of ESRD (1057 [33.9%] cases with simvastatin plus ezetimibe versus 1084 [34.6%] cases with placebo; rate ratio, 0.97; 95% confidence interval [95% CI], 0.89 to 1.05; P=0.41). Similarly, allocation to simvastatin plus ezetimibe had no significant effect on the prespecified tertiary outcomes of ESRD or death (1477 [47.4%] events with treatment versus 1513 [48.3%] events with placebo; rate ratio, 0.97; 95% CI, 0.90 to 1.04; P=0.34) or ESRD or doubling of baseline creatinine (1189 [38.2%] events with treatment versus 1257 [40.2%] events with placebo; rate ratio, 0.93; 95% CI, 0.86 to 1.01; P=0.09). Exploratory analyses also showed no significant effect on the rate of change in eGFR. Lowering LDL cholesterol by 1 mmol/L did not slow kidney disease progression within 5 years in a wide range of patients with CKD.

Background: Patients (pts) with severe aortic regurgitation (AI) often present with symptoms of shortness of breath (SOB) or heart failure (HF); however, the effect of these symptoms and severity of aortic regurgitation on patient-perceived health status is unknown. Methods: Kansas City Cardiomyopathy Questionnaire (KCCQ) data were collected using tablet computers from pts presenting for routine outpatient cardiovascular assessment between 6/1/2011 and 8/31/2012 who also underwent echocardiography within 90 days. Pts with other valvular lesions (including aortic stenosis) moderate or greater in severity, congenital heart disease, hypertrophic cardiomyopathy, pericarditis or constriction, cardiac amyloid, sarcoid, restrictive cardiomyopathy, or pulmonary hypertension were excluded. Demographic, clinical, historical, and echocardiographic data was collected as per routine. Multiple linear regression was used to assess the association of this information and valve lesion severity with KCCQ summary score (SS). Results: 590 pts [age 61.9±13.8 years, 363 (61.5%) men, 132 (22%) with prior aortic valve surgery] were identified; 452 with mild, 86 with moderate and 52 with severe AI. Mean KCCQ SS was 74.5±23.7; 74.3±23.0 with mild AI, 73.8±26.2 with moderate AI, and 76.7±19.4 with severe AI (p=NS). SOB was present in 290 pts (49%, KCCQ SS 65.3±23.7), HF in 43 (7.3%, KCCQ SS 50.1±22.3) and both in 36 pts (KCCQ SS 47.0±21.7). After adjusting for multiple factors, linear regression (r2=0.28, p Conclusions: In stable outpatients with AI, KCCQ scores correlate with the presence of shortness of breath and heart failure symptoms, but are not affected by the degree of AI or history of aortic valve surgery. Symptoms rather than diagnosis drives patient perceived health status.

STE20/SPS-1-related proline-alanine-rich protein kinase (SPAK) and oxidative stress-related kinase (OSR1) activate the potassium-dependent sodium-chloride co-transporter, NKCC2, and thiazide-sensitive sodium-chloride cotransporter, NCC, in vitro, and both co-localize with a kinase regulatory molecule, Cab39/MO25α, at the apical membrane of the thick ascending limb (TAL) and distal convoluted tubule (DCT). Yet genetic ablation of SPAK in mice causes a selective loss of NCC function, whereas NKCC2 becomes hyperphosphorylated. Here, we explore the underlying mechanisms in wild-type and SPAK-null mice. Unlike in the DCT, OSR1 remains at the TAL apical membrane of KO mice where it is accompanied by an increase in the active, phosphorylated form of AMP-activated kinase. We found an alterative SPAK isoform (putative SPAK2 form), which modestly inhibits co-transporter activity in vitro, is more abundant in the medulla than the cortex. Thus, enhanced NKCC2 phosphorylation in the SPAK knock-out may be explained by removal of inhibitory SPAK2, sustained activity of OSR1, and activation of other kinases. By contrast, the OSR1/SPAK/M025α signaling apparatus is disrupted in the DCT. OSR1 becomes largely inactive and displaced from M025α and NCC at the apical membrane, and redistributes to dense punctate structures, containing WNK1, within the cytoplasm. These changes are paralleled by a decrease in NCC phosphorylation and a decrease in the mass of the distal convoluted tubule, exclusive to DCT1. As a result of the dependent nature of OSR1 on SPAK in the DCT, NCC is unable to be activated. Consequently, SPAK(-/-) mice are highly sensitive to dietary salt restriction, displaying prolonged negative sodium balance and hypotension.

ROMK channels are well-known to play a central role in renal K secretion, but the absence of highly specific and avid-ROMK antibodies has presented significant roadblocks toward mapping the extent of expression along the entire distal nephron and determining whether surface density of these channels is regulated in response to physiological stimuli. Here, we prepared new ROMK antibodies verified to be highly specific, using ROMK knockout mice as a control. Characterization with segmental markers revealed a more extensive pattern of ROMK expression along the entire distal nephron than previously thought, localizing to distal convoluted tubule regions, DCT1 and DCT2; the connecting tubule (CNT); and cortical collecting duct (CD). ROMK was diffusely distributed in intracellular compartments and at the apical membrane of each tubular region. Apical labeling was significantly increased by high-K diet in DCT2, CNT1, CNT2, and CD ( P < 0.05) but not in DCT1. Consistent with the large increase in apical ROMK, dramatically increased mature glycosylation was observed following dietary potassium augmentation. We conclude 1) our new antibody provides a unique tool to characterize ROMK channel localization and expression and 2) high-K diet causes a large increase in apical expression of ROMK in DCT2, CNT, and CD but not in DCT1, indicating that different regulatory mechanisms are involved in K diet-regulated ROMK channel functions in the distal nephron.

Large, Ca-activated K channels (BK) are comprised of an α pore (BKα) and one of four β subunits (BKβ1–4). When the gene for BKβ1 is knocked out (BKβ1-KO), the result is increased myogenic tone of vascular smooth muscle and hypertension. We reexamined whether the hypertension is entirely due to increased vascular tone, because most monogenic forms of hypertension have renal origins and BKβ1 resides in renal connecting tubule (CNT) cells. Moreover, BKβ1 is localized in the adrenal glands, where it may control production of aldosterone. This review will summarize our report that a majority of the hypertension of BKβ1-KO is the result of insufficient handling of dietary K, resulting in increased plasma K and hyperaldosteronism, the latter promoting Na and fluid retention. The fluid retention and hypertension are exacerbated by a high-K diet and reduced by eplerenone, an aldosterone receptor inhibitor. Genetic knockout of BKβ4 (BKβ4-KO), which resides in intercalated cells, also exhibits deficient K excretion, fluid retention, and mild hypertension that is not exacerbated when animals are treated with a high-K diet. These results show that the hypertension associated with BKβ1-KO occurs because of enhanced fluid retention, as well as because of the previously described vascular dysfunction.

Large-conductance, calcium-activated potassium channels (BK) are expressed in principal cells (PC) and intercalated cells (IC) in mammalian nephrons as BK-alpha/beta1 and BK-alpha/beta4, respectively. IC, which protrude into the lumens of tubules, express substantially more BK than PC despite lacking sufficient Na-K-ATPase to support K secretion. We previously showed in mice that IC exhibit size reduction when experiencing high distal flows induced by a high-K diet. We therefore tested the hypothesis that BK-alpha/beta4 are regulators of IC volume via a shear stress (tau)-induced, calcium-dependent mechanism, resulting in a reduction in intracellular K content. We determined by Western blot and immunocytochemical analysis that C11-Madin-Darby canine kidney cells contained a predominance of BK-alpha/beta4. To determine the role of BK-alpha/beta4 in tau-induced volume reduction, we exposed C11 cells to tau and measured K efflux by flame photometry and cell volume by calcein staining, which changes inversely to cell volume. With 10 dynes/cm(2), calcein intensity significantly increased 39% and monovalent cationic content decreased significantly by 37% compared with static conditions. Furthermore, the shear-induced K loss from C11 was abolished by the reduction of extracellular calcium, addition of 5 mM TEA, or BK-beta4 small interfering (si) RNA, but not by addition of nontarget siRNA. These results show that BK-alpha/beta4 plays a role in shear-induced K loss from IC, suggesting that BK-alpha/beta4 regulate IC volume during high-flow conditions. Furthermore, these results support the use of C11 cells as in vitro models for studying BK-related functions in IC of the kidney.

Introduction: In select patients with systolic heart failure, cardiac resynchronization therapy (CRT) has been shown to improve quality of life, exercise capacity, ejection fraction (EF), and survival. Little is known about the response to CRT in patients with right bundle branch block (RBBB) or non-specific intraventricular conduction delay (IVCD) compared with traditionally studied patients with left bundle branch block (LBBB). Methods: We assessed 542 consecutive patients presenting for the new implantation of a CRT device. Patients were placed into one of three groups based on the preimplantation electrocardiogram morphology: LBBB, RBBB, or IVCD. Patients with a narrow QRS or paced ventricular rhythm were excluded. The primary endpoint was long-term survival. Secondary endpoints were changes in EF, left ventricular end-diastolic and systolic diameter, mitral regurgitation, and New York Heart Association (NYHA) functional class. Results: Three hundred and thirty-five patients met inclusion criteria of which 204 had LBBB, 38 RBBB, and 93 IVCD. There were 32 deaths in the LBBB group, 10 in the RBBB, and 27 in the IVCD group over a mean follow up of 3.4 ± 1.2 years. In multivariate analysis, no mortality difference amongst the three groups was noted. Patients with LBBB had greater improvements in most echocardiographic endpoints and NYHA functional class than those with IVCD and RBBB. Conclusion: There is no difference in 3-year survival in patients undergoing CRT based on baseline native QRS morphology. Patients with RBBB and IVCD derive less reverse cardiac remodeling and symptomatic benefit from CRT compared with those with a native LBBB. (PACE 2010; 590–595)

On a low-Na+ diet (LNa+), urinary Na+ loss is prevented by aldosterone-induced Na+ reabsorption through epithelial Na+ channels (ENaC) in the connecting tubules (CNT) and cortical collecting ducts (CCD). However, the mechanism whereby K+ loss is minimized and Na+ reabsorption is maximized in the face of a reduced lumen-to-bath Na+ gradient is not fully understood. The large-conductance calcium-activated potassium channel (BK)β1 subunit (gene: Kcnmb1), which has a role in K+ secretion in the CNT, is absent in the CCD in mice on a control diet. We hypothesized that BKα/β1 helps to maximize Na+ reabsorption during Na+ deficiency. With LNa+, the Na+ clearance of Kcnmb1-mutant mice ( Kcnmb1−/−) was 45% greater and the plasma Na+ concentration and osmolality were significantly reduced compared with wild-type mouse (WT) controls. On LNa+, Kcnmb1−/− exhibited exacerbated volume depletion (higher Hct and weight loss) compared with WT. LNa+, which did not affect the mean arterial blood pressure (MAP) of WT, significantly reduced MAP of Kcnmb1−/−. The plasma aldosterone concentration of Kcnmb1−/− on LNa+ was significantly elevated compared with Kcnmb1−/− on a control diet but was not different from WT on LNa+. Immunohistochemical staining revealed that BKα and BKβ1, which were absent in the principal cells (PCs) of the CCD, were localized on the basolateral membrane (BSM) of PCs of WT on LNa+. Moreover, BKα was absent from the BSM of PCs of Na+-deficient Kcnmb1−/−. We conclude that part of the mechanism to maximize Na+ reabsorption during Na+ deficiency is the placement of BKα/β1 channels in the BSM of CCD PCs.

Mice lacking the β1-subunit (gene, Kcnmb1 ; protein, BK-β1) of the large Ca-activated K channel (BK) are hypertensive. This phenotype is thought to result from diminished BK currents in vascular smooth muscle where BK-β1 is an ancillary subunit. However, the β1-subunit is also expressed in the renal connecting tubule (CNT), a segment of the aldosterone-sensitive distal nephron, where it associates with BK and facilitates K secretion. Because of the correlation between certain forms of hypertension and renal defects, particularly in the distal nephron, it was determined whether the hypertension of Kcnmb1 −/− has a renal origin. We found that Kcnmb1 −/− are hypertensive, volume expanded, and have reduced urinary K and Na clearances. These conditions are exacerbated when the animals are fed a high K diet (5% K; HK). Supplementing HK-fed Kcnmb1 −/− with eplerenone (mineralocorticoid receptor antagonist) corrected the fluid imbalance and more than 70% of the hypertension. Finally, plasma [aldo] was elevated in Kcnmb1 −/− under basal conditions (control diet, 0.6% K) and increased significantly more than wild type when fed the HK diet. We conclude that the majority of the hypertension of Kcnmb1 −/− is due to aldosteronism, resulting from renal potassium retention and hyperkalemia.

In analogy to the chiral-linear multiplet correspondence we establish a relationship between the 3-form (or gaugino condensate) multiplet and a coupled non-minimal (0,1/2) multiplet, illustrated by a simple explicit example.

Purpose of review Large, BK (calcium-activated potassium) channels are now regarded as relevant players in many aspects of renal physiology, including potassium secretion. This review will highlight recent discoveries regarding the function and localization of BK in the kidney. Recent findings Patch clamp electrophysiology has revealed BK in cultured podocytes, glomerular mesangial cells, and in several tubule segments including principal cells (connecting tubules/principal cells), and intercalated cells of connecting tubules and cortical collecting ducts. Flow-induced potassium secretion is mediated by BK in the distal nephron and may be partly the result of shear stress-induced increases in cell calcium concentrations. ROMK-/- and wild-type mice on a high potassium diet exhibit BK-mediated potassium secretion, and studies of BK-alpha-/- and BK-beta1-/- mice suggest that flow-induced potassium secretion is mediated by BK-alpha/beta1, which is specifically localized in the apical membrane of the connecting tubule of the mouse and connecting tubule plus initial cortical collecting duct of the rabbit. Summary BK channels, located in glomerular cells and in many nephron segments, especially mediate potassium secretion in the combined condition of potassium adaptation and high flow. Understanding the molecular makeup of BK in specific renal cells and the dietary and physiological conditions for their expression can yield improved potassium-sparing compounds.

Thiazide diuretics are used to treat hypertension; however, compensatory processes in the kidney can limit antihypertensive responses to this class of drugs. Here, we evaluated compensatory pathways in SPAK kinase-deficient mice, which are unable to activate the thiazide-sensitive sodium chloride cotransporter NCC (encoded by Slc12a3). Global transcriptional profiling, combined with biochemical, cell biological, and physiological phenotyping, identified the gene expression signature of the response and revealed how it establishes an adaptive physiology. Salt reabsorption pathways were created by the coordinate induction of a multigene transport system, involving solute carriers (encoded by Slc26a4, Slc4a8, and Slc4a9), carbonic anhydrase isoforms, and V-type H⁺-ATPase subunits in pendrin-positive intercalated cells (PP-ICs) and ENaC subunits in principal cells (PCs). A distal nephron remodeling process and induction of jagged 1/NOTCH signaling, which expands the cortical connecting tubule with PCs and replaces acid-secreting α-ICs with PP-ICs, were partly responsible for the compensation. Salt reabsorption was also activated by induction of an α-ketoglutarate (α-KG) paracrine signaling system. Coordinate regulation of a multigene α-KG synthesis and transport pathway resulted in α-KG secretion into pro-urine, as the α-KG-activated GPCR (Oxgr1) increased on the PP-IC apical surface, allowing paracrine delivery of α-KG to stimulate salt transport. Identification of the integrated compensatory NaCl reabsorption mechanisms provides insight into thiazide diuretic efficacy.

Large, Ca2+-activated K+channels (BK), comprised of α- and β-subunits, mediate K+secretion during high flow rates in distal nephron segments. Because the BK-β1 subunit enhances Ca2+sensitivity of BK in a variety of cells, we determined its role in flow-induced K+secretion and its localization in the mammalian nephron. To determine the role of BK-β1 in the kaliuretic response to volume expansion, the rate of K+excretion (UKV) vs. varied urinary flow rates were determined in wild-type and BK-β1 knockout mice (BK-β1−/−). When flow rate was varied by volume expansion (2 ml·h−1·25 g body wt−1) for 30 to 60 min in wild-type mice, we found that the UKV increased significantly with increasing urine flow rates ( r2= 0.50, P < 0.00001, n = 31), as demonstrated previously in distal nephron of rats and rabbits. However, in BK-β1−/−mice, UKV did not vary with changing flow rates ( r2= 0.15, P = 0.08, n = 20). Using immunohistochemical techniques, we found that BK-β1 was strongly expressed in the apical membrane of the murine distal nephron and that 98% of BK-β1 protein detected by histochemistry colocalized with NCX, a marker of connecting tubules (CNT). Both BK-β1 and NCX colocalized with BK-α in separate experiments. Furthermore, we confirmed BK-β1 protein expression in the apical membrane of connecting tubules in rabbits. BK-β1 RNA from rabbit CNT was sequenced and was identical to previously published rabbit muscle sequences. These data show that the BK-β1 accessory subunit is present in the CNT segment of the mammalian distal nephron and has a significant role in the kaliuretic response to increased urinary flow induced by volume expansion.

Background: Data regarding long-term outcomes in patients with cardiovascular (CV) pseudoaneurysms (PSA) is sparse. In patients with prior CV surgery, we sought to assess outcomes in patients with PSAs (defined as paravalvular, aortic root, or ascending aorta PSAs) & compare them with matched controls. Methods: As part of a cohort study (total n=342), we included 114 patients with prior CV surgery who presented with paravalvular (n=71, 59 at the aortic valve & 12 at the mitral valve) & ascending aortic (n=43) PSAs. A control group of patients (n=228) with prior CV surgery, matched in a 2:1 fashion based on age, gender, type & time of CV surgery, were also included. Standard clinical, echocardiographic & surgical data was collected & Euroscore was calculated. A composite endpoint of death & stroke during follow-up were recorded. Results: Baseline data are shown in Figure A. 80% of patients in each group underwent redo CV surgery during follow-up. Over a follow-up of 6.7±4 years, there were 78 (23%) events (32 or 28% in PSA group & 46 or 20% in control group). 30-day events occurred in 7% of the PSA group & 1% of controls. Kaplan-Meier survival curves for the 2 groups are shown in Figure B. In the multivariate Cox Survival Analysis, Euroscore (HR 1.18 [1.10-1.27]) & the presence of PSA (HR 2.83 [1.66-4.85]) predicted a higher rate of events, while subsequent CV surgery (as a time-dependent covariate HR 0.38 [0.22-0.67])) & antibiotic use (HR 0.29 [0.27-0.31]) predicted improved freedom from events (all p Conclusion: In patients with prior CV surgery, the presence of a cardiac PSA was associated with increased long-term adverse events, while redo CV surgery and antibiotic use improved outcomes.

The NaCl cotransporter (NCC) of the renal distal convoluted tubule is stimulated by low-K+ diet by an unknown mechanism. Since recent work has shown that the STE20/SPS-1-related proline-alanine-rich protein kinase (SPAK) can function to stimulate NCC by phosphorylation of specific N-terminal sites, we investigated whether the NCC response to low-K+ diet is mediated by SPAK. Using phospho-specific antibodies in Western blot and immunolocalization studies of wild-type and SPAK knockout (SPAK−/−) mice fed a low-K+ or control diet for 4 days, we found that low-K+ diet strongly increased total NCC expression and phosphorylation of NCC. This was associated with an increase in total SPAK expression in cortical homogenates and an increase in phosphorylation of SPAK at the S383 activation site. The increased pNCC in response to low-K+ diet was blunted but not completely inhibited in SPAK−/− mice. These findings reveal that SPAK is an important mediator of the increased NCC activation by phosphorylation that occurs in the distal convoluted tubule in response to a low-K+ diet, but other low-potassium-activated kinases are likely to be involved.

The superspace geometry of Chern-Simons forms is shown to be closely related to that of the 3-form multiplet. This observation allows to simplify considerably the geometric structure of supersymmetric Chern-Simons forms and their coupling to linear multiplets. The analysis is carried through in U_K(1) superspace, relevant at the same time for supergravity-matter couplings and for chirally extended supergravity.

The highly sialylated vascular endothelial surface undergoes changes in sialylation upon adopting the migratory/angiogenic phenotype. We recently established endothelial cell (EC) expression of NEU1 sialidase (Cross, A. S., Hyun, S. W., Miranda-Ribera, A., Feng, C., Liu, A., Nguyen, C., Zhang, L., Luzina, I. G., Atamas, S. P., Twaddell, W. S., Guang, W., Lillehoj, E. P., Puche, A. C., Huang, W., Wang, L. X., Passaniti, A., and Goldblum, S. E. (2012) NEU1 and NEU3 sialidase activity expressed in human lung microvascular endothelia. NEU1 restrains endothelial cell migration whereas NEU3 does not. J. Biol. Chem. 287, 15966–15980). We asked whether NEU1 might regulate EC capillary-like tube formation on a Matrigel substrate. In human pulmonary microvascular ECs (HPMECs), prior silencing of NEU1 did not alter tube formation. Infection of HPMECs with increasing multiplicities of infection of an adenovirus encoding for catalytically active WT NEU1 dose-dependently impaired tube formation, whereas overexpression of either a catalytically dead NEU1 mutant, NEU1-G68V, or another human sialidase, NEU3, did not. NEU1 overexpression also diminished EC adhesion to the Matrigel substrate and restrained EC migration in a wounding assay. In HPMECs, the adhesion molecule, CD31, also known as platelet endothelial cell adhesion molecule-1, was sialylated via α2,6-linkages, as shown by Sambucus nigra agglutinin lectin blotting. NEU1 overexpression increased CD31 binding to Arachis hypogaea or peanut agglutinin lectin, indicating CD31 desialylation. In the postconfluent state, when CD31 ectodomains are homophilically engaged, NEU1 was recruited to and desialylated CD31. In postconfluent ECs, CD31 was desialylated compared with subconfluent cells, and prior NEU1 silencing completely protected against CD31 desialylation. Prior CD31 silencing and the use of CD31-null ECs each abrogated the NEU1 inhibitory effect on EC tube formation. Sialyltransferase 6 GAL-I overexpression increased α2,6-linked CD31 sialylation and dose-dependently counteracted NEU1-mediated inhibition of EC tube formation. These combined data indicate that catalytically active NEU1 inhibits in vitro angiogenesis through desialylation of its substrate, CD31.

Starting from flat two-dimensional gauge potentials we propose the notion of ${\cal W}$-gauge structure in terms of a nilpotent BRS differential algebra. The decomposition of the underlying Lie algebra with respect to an $SL(2)$ subalgebra is crucial for the discussion conformal covariance, in particular the appearance of a projective connection. Different $SL(2)$ embeddings lead to various ${\cal W}$-gauge structures. We present a general soldering procedure which allows to express zero curvature conditions for the ${\cal W}$-currents in terms of conformally covariant differential operators acting on the ${\cal W}$ gauge fields and to obtain, at the same time, the complete nilpotent BRS differential algebra generated by ${\cal W}$-currents, gauge fields and the ghost fields corresponding to ${\cal W}$-diffeomorphisms. As illustrations we treat the cases of $SL(2)$ itself and to the two different $SL(2)$ embeddings in $SL(3)$, {\it viz.} the ${\cal W}_3^{(1)}$- and ${\cal W}_3^{(2)}$-gauge structures, in some detail. In these cases we determine algebraically ${\cal W}$-anomalies as solutions of the consistency conditions and discuss their Chern-Simons origin., Comment: 46 pages,LaTeX

Although elevated plasma cholesterol levels represent a well-established and significant risk for developing atherosclerosis, there is a wide spectrum of cholesterol levels in patients with coronary artery disease (CAD). Most secondary prevention studies have generated convincing evidence that cholesterol reduction in patients with high cholesterol levels is associated with improved clinical outcome by reducing risk of further cardiovascular events. However, other risk factors may play a prominent role in the pathogenesis of coronary disease in the majority of patients with near-normal cholesterol values. The Cholesterol and Recurrent Events (CARE) study was designed to address whether the pharmacologic reduction of cholesterol levels with the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, pravastatin, would reduce the sum of fatal coronary artery disease (CAD) and nonfatal myocardial infarction (Ml) in patients who have survived an Ml yet have a total cholesterol value

This review summarizes recent studies of hypertension associated with a defect in renal K excretion due to genetic deletions of various components of the large, Ca-activated K channel (BK), and describes new evidence and theories regarding K secretory roles of BK in intercalated cells.Isolated perfused tubule methods have revealed the importance of BK in flow-induced K secretion. Subsequently, mice with genetically deleted BK subunits revealed the complexities of BK-mediated K secretion. Deletion of BKα results in extreme aldosteronism, hypertension, and an absence of flow-induced K secretion. Deletion of the BKβ1 ancillary subunit results in decreased handling of a K load, increased plasma K, mild aldosteronism and hypertension that is exacerbated by a high K diet. Deletion of BKβ4 (β4KO) leads to insufficient K handling, high plasma K, fluid retention, but with milder hypertension. Fluid retention in β4KO may be the result of insufficient flow-induced secretion of adenosine triphosphate (ATP), which normally inhibits epithelial Na channels (ENaCs).Classical physiological analysis of electrolyte handling in knockout mice has enlightened our understanding of the mechanism of handling K loads by renal K channels. Studies have focused on the different roles of BK-α/β1 and BK-α/β4 in the kidney. BKβ1 hypertension may be a 'three-hit' hypertension, involving a K secretory defect, elevated production of aldosterone, and increased vascular tone. The disorders observed in BK knockout mice have shed new insights on the importance of proper renal K handling for maintaining volume balance and blood pressure.