High Salt Intake-Increased (Pro)renin Receptor Expression Is Exaggerated in the Kidney of Dahl Salt-Sensitive Rats.

The (P)RR ([pro]renin receptor) was identified as a new component of the renin-angiotensin system. We previously reported that high salt (HS) intake increased the (P)RR expression in several nephron segments of Sprague-Dawley rats. Other studies reported HS intake increased the XO (xanthine oxidase) activity and an MR (mineralocorticoid receptor) antagonist inhibited HS intake-increased (P)RR expression in the kidneys of Dahl salt-sensitive (DS) rats. The present study examined the effects of HS intake on (P)RR expression in the kidney of DS rats. Male DS rats were fed a normal salt diet or an HS diet for 4 weeks. Some of the rats fed on the HS diet were treated with the XO inhibitor, febuxostat, and the MR antagonist, spironolactone. Immunoblot and immunohistochemical analyses showed that HS intake increased (P)RR expression in the renal cortex by 22.6-fold, the proximal tubules by 4.9-fold and the distal tubules, respectively. Both febuxostat and spironolactone inhibited HS intake-increased (P)RR expression in the renal cortex. Febuxostat inhibited HS intake-increased (P)RR expression in the proximal tubules, whereas spironolactone inhibited HS intake-increased (P)RR expression in the distal tubules. Additionally, deoxycorticosterone acetate increased (P)RR expression in the renal cortex and distal tubules but not in the proximal tubules of DS rats fed the normal salt diet. These results indicate that HS intake greatly increases (P)RR expression in the renal cortex of DS rats. The mechanisms of HS intake-increased (P)RR expression may work in an XO-dependent manner in the proximal tubules and an MR-dependent manner in the distal tubules.

Biochemical evidence of cell starvation in diabetic hemodialysis patients.

Recently, the ratio of patients with diabetes mellitus (DM) among hemodialysis (HD) patients has increased to become the largest sub-population. Their prognoses are significantly worse than those of patients without diabetes (non-DM). In the present study, 10 DM patients who did not take meals and 10 non-DM patients who took meals during HD sessions were investigated. The time courses of the change in plasma levels of metabolites during HD were determined. DM patients exhibited decreased plasma levels of lactate, pyruvate and alanine and dramatically increased levels of ketone bodies. At the end of HD, the plasma levels of lactate, pyruvate, alanine and ketone body were 0.46 ± 0.07, 0.026 ± 0.01, 0.12 ± 0.04 and 0.26 ± 0.04 mM (mean ± standard error), respectively. The profile was 'hypolactatemia and hyperketonemia', indicating non-homeostasis. Glycolysis and tricarboxylic acid cycle were suppressed, and the oxidation of fatty acid was accelerated, indicating starvation, even though high amounts of glucose (150 mg/dl) in dialysate were supplied continuously to the bloodstream. In contrast, the plasma levels of lactate, pyruvate, and alanine in the non-DM patients were increased, with the levels of ketone body remaining low during HD to maintain homeostasis, indicating accelerated glycolysis. Furthermore, their plasma levels of insulin increased from 8.1 ± 1.4 to 19.8 ± 3.4 µU/ml, which indicated endogenous secretion stimulated by glucose in dialysate and meal intake. In contrast, in the DM patients, the levels decreased from 19.2 ± 3.4 to 5.5 ± 1.1 µU/ml. This value was the lower limit of the normal range. The depletion of the insulin through extracorporeal circulation may inhibit the transportation of glucose from the blood into the muscles, with the consequence of cell starvation. Such cell starvation along with lipolysis every two days may accelerate proteolysis and affect the prognosis of DM patients.

Acidic organelles mediate TGF-ß1-induced cellular fibrosis via (pro)renin receptor and vacuolar ATPase trafficking in human peritoneal mesothelial cells.

TGF-ß1, which can cause renal tubular injury through a vacuolar-type H+-ATPase (V-ATPase)-mediated pathway, is induced by the glucose degradation product methylglyoxal to yield peritoneal injury and fibrosis. The present study investigated the roles of V-ATPase and its accessory protein, the (pro)renin receptor, in peritoneal fibrosis during peritoneal dialysis. Rats daily administered 20 mM methylglyoxal intraperitoneally developed significant peritoneal fibrosis after 7 days with increased expression of TGF-ß and V-ATPase, which was reduced by the inhibition of V-ATPase with co-administration of 100 mM bafilomycin A1. The (pro)renin receptor and V-ATPase were expressed in acidic organelles and cell membranes of human peritoneal mesothelial cells. TGF-ß1 upregulated the expression of collagens, α-SMA, and EDA-fibronectin, together with ERK1/2 phosphorylation, which was reduced by inhibition of V-ATPase, (pro)renin receptor, or the MAPK pathway. Fibronectin and the soluble (pro)renin receptor were excreted from cells by acidic organelle trafficking in response to TGF-ß1; this excretion was also suppressed by inhibition of V-ATPase. Soluble (pro)renin receptor concentrations in effluents of patients undergoing peritoneal dialysis were associated with the dialysate-to-plasma ratio of creatinine. Together, these results demonstrate a novel fibrosis mechanism through the (pro)renin receptor and V-ATPase in the acidic organelles of peritoneal mesothelial cells.

Expression of (Pro)renin Receptor During Rapamycin-Induced Erythropoiesis in K562 Erythroleukemia Cells and Its Possible Dual Actions on Erythropoiesis.

(Pro)renin receptor ((P)RR), a specific receptor for renin and prorenin, is expressed in erythroblastic cells. (P)RR has multiple biological actions: prorenin activation, stimulation of the intracellular signaling including extracellular signal-regulated kinases, and functional complex formation with vacuolar H+-ATPase (v-ATPase). However, the functional implication of (P)RR in erythroblast cells has not been clarified. The aim of the present study was to clarify changes of (P)RR expression during erythropoiesis and a role of (P)RR in the heme synthesis. (P)RR expression was studied during rapamycin-induced erythropoiesis in a human erythroleukemia cell line, K562. Treatment with rapamycin (100 nM) for 48 hours significantly increased %number of hemoglobin-producing cells, γ-globin mRNA levels, erythroid specific 5-aminolevulinate synthase (ALAS2) mRNA levels, and heme content in K562 cells. Both (P)RR protein and mRNA levels increased about 1.4-fold during rapamycin-induced erythropoiesis. Suppression of (P)RR expression by (P)RR-specific small interference RNA increased ALAS2 mRNA levels about 1.6-fold in K562 cells, compared to control using scramble RNA, suggesting that (P)RR may down-regulate ALAS2 expression. By contrast, treatment with bafilomycin A1, an inhibitor of v-ATPase, decreased greatly % number of hemoglobin-producing cells and heme content in K562 cells, indicating that the v-ATPase function is essential for hemoglobinization and erythropoiesis. Treatment with bafilomycin A1 increased (P)RR protein and mRNA levels. In conclusion, we propose that (P)RR has dual actions on erythropoiesis: the promotion of erythropoiesis via v-ATPase function and the down-regulation of ALAS2 mRNA expression. Thus, (P)RR may contribute to the homeostatic control of erythropoiesis.

Water Deprivation Increases (Pro)renin Receptor Levels in the Kidney and Decreases Plasma Concentrations of Soluble (Pro)renin Receptor.

Water deprivation activates the renin-angiotensin system. We have hypothesized that the renal expression of (pro)renin receptor ((P)RR), a specific receptor for renin and prorenin, could be changed under dehydration. Moreover, plasma levels of soluble (P)RR (s(P)RR) comprising of the extracellular domain of (P)RR may reflect the renal (P)RR expression. In the present study, we therefore aimed to clarify changes of plasma s(P)RR concentrations and kidney tissue (P)RR levels using rats with dehydration. Male Wister-Kyoto rats were divided into two groups; dehydrated (DH) rats deprived of water for 72 hours with free access to food, and control rats. Plasma s(P)RR concentrations measured by enzyme-linked immunosorbent assay were significantly lower in DH rats (6.94 ± 2.08 ng/mL, mean ± SD, n = 5) than in control (12.54 ± 2.00 ng/mL, n = 5) (p < 0.05). Western blot analysis confirmed lower expression levels of s(P)RR in plasma in DH rats than in control. By contrast, western blot analysis showed higher levels of full-length (P)RR and lower levels of furin (an enzyme responsible for generation of s(P)RR from full-length (P)RR) in the kidney tissues obtained from DH rats compared to control. There was no significant difference in the renal (P)RR mRNA levels between DH rats and control. These findings suggest that water deprivation may elevate the renal full-length (P)RR levels via reducing the expression of furin. Increased full-length (P)RR may contribute to the up-regulation of the renal renin-angiotensin system and the production of concentrated urine under dehydration.

Association between N-terminal pro B-type natriuretic peptide and day-to-day blood pressure and heart rate variability in a general population: the Ohasama study.

BACKGROUND: In addition to day-to-day variability in blood pressure (BP) or heart rate (HR), N-terminal pro B-type natriuretic peptide (NT-proBNP) has been reported to be a predictor of cardiovascular disease. Here, we tested the hypothesis that day-to-day BP or HR variability calculated as the intraindividual standard deviation (SD) of home BP or HR is associated with elevated NT-proBNP in a cross-sectional study. METHODS: Among 664 participants (mean age, 61.9 years; female, 70.5%) from a general Japanese population without a history of heart disease, 86 (13.0%) had NT-proBNP at least 125 pg/ml. RESULTS: Each 1 SD increase in the SD of home systolic BP (SBP) [odds ratio (OR), 1.82; P < .0001) and in the SD of home HR (OR, 1.44; P = 0.008) were significantly associated with the prevalence of NT-proBNP at least 125 pg/ml after adjustment for possible confounding factors including home SBP and HR. Among the four groups defined by the median SD of home SBP and of home HR, the group with higher SDs in home SBP (≥8.0 mmHg) and HR (≥5.0 bpm) had the greatest OR for the prevalence of NT-proBNP at least 125 pg/ml (OR, 4.80; P = 0007 vs. a reference group with lower SDs of home SBP and HR). CONCLUSION: These results suggest that day-to-day variability in BP and HR may be associated with target-organ damage or complications, which can lead to an elevated NT-proBNP level. An elevated NT-proBNP level may be involved in the prognostic significance of day-to-day variability in BP or HR.

(Pro)renin receptor is crucial for Wnt/ß-catenin-dependent genesis of pancreatic ductal adenocarcinoma.

Although Wnt/ß-catenin signaling is known to be aberrantly activated in PDAC, mutations of CTNNB1, APC or other pathway components are rare in this tumor type, suggesting alternative mechanisms for Wnt/ß-catenin activation. Recent studies have implicated the (pro)renin receptor ((P)RR) is related to the Wnt/ß-catenin signaling pathway. We therefore investigated the possible role of (P)RR in pancreatic carcinogenesis. Plasma s(P)RR levels were significantly (P < 0.0001) higher in patients with PDAC than in healthy matched controls. We also identified aberrant expression of (P)RR in premalignant PanIN and PDAC lesions and all the PDAC cell lines examined. Inhibiting (P)RR with an siRNA attenuated activation of Wnt/ß-catenin signaling pathway and reduced the proliferative ability of PDAC cells in vitro and the growth of engrafted tumors in vivo. Loss of (P)RR induced apoptosis of human PDAC cells. This is the first demonstration that (P)RR may be profoundly involved in ductal tumorigenesis in the pancreas.

Expression of (pro)renin receptor and its upregulation by high salt intake in the rat nephron.

A functional receptor for renin and prorenin ((P)RR) was identified as a new component of the renin-angiotensin system. The precise localization of (P)RR in the kidney has not been clarified. The present study was designed to determine the localization of (P)RR in the rat nephron and to investigate the regulation of renal (P)RR expression by high salt (HS) intake. (P)RR mRNA levels in the kidney sections and isolated nephron segments were examined using reverse transcription and polymerase chain reaction (RT-PCR), and (P)RR protein levels were examined by immunoblot and immunohistochemical analyses. Renal (P)RR mRNA and protein levels in rats fed a HS diet for 4 weeks were also compared with those fed a normal salt diet. (P)RR mRNA was expressed in various nephron segments of the cortex and medulla; glomeruli (Glm), proximal tubules (PT), thick ascending limbs (TAL) and collecting ducts (CD). (P)RR protein was highly expressed in the PT, medullary TAL (MTAL) and inner medullary CD (IMCD), and lowly in the preglomerular arterioles (Art) and Glm. HS intake increased (P)RR protein levels in the Glm, PT and tubules of medullary rays. These results indicated that (P)RR is expressed throughout various nephron segments and Art, and that (P)RR protein is expressed predominantly in the PT, MTAL and IMCD. HS intake appears to upregulate the (P)RR expression in the Glm, PT and tubules of medullary rays, suggesting that (P)RR may be involved in the regulation of renal function and HS-induced disorders.

A functional (pro)renin receptor is expressed in human lymphocytes and monocytes.

The renin-angiotensin system (RAS) is involved in inflammation. The signaling via the ANG II type 1 receptor in human lymphocytes and monocytes, which play key roles in pathophysiology of glomerulonephritis (GN), can enhance inflammation. However, the role of the (pro)renin receptor [(P)RR], a component of the RAS, in inflammatory reactions is unknown. We assessed whether (P)RR is expressed in human lymphocytes and monocytes by RT-PCR, Western blotting, flow cytometry, and immunohistochemistry, and whether (P)RR functions in inflammation. (P)RR mRNA and protein were expressed in human peripheral blood mononuclear cells (PBMCs). Flow cytometric analysis revealed high expression of (P)RR on monocytes. (P)RR was present on PBMCs, infiltrating lymphocytes, and macrophages around glomeruli with a crescent in anti-neutrophil cytoplasmic antibody (ANCA)-associated GN. Renin stimulation of PBMCs from healthy subjects in the presence of the ANG II type 1 receptor and ANG II type 2 receptor blockers induced ERK1/2 phosphorylation and release of IL-6 and expression of cyclooxygenase-2 (COX-2). The increases in cytokine release and COX-2 expression were inhibited in the presence of an ERK1/2 inhibitor. (P)RR knockdown by small interfering RNA in U937 cells, a human leukemic monocyte lymphoma cell line, significantly decreased ERK1/2 phosphorylation after renin stimulation. Thus (P)RR expressed in human inflammatory cells might contribute to inflammation in ANCA-associated GN.

Association of aldosterone-to-renin ratio with hypertension differs by sodium intake: the Ohasama study.

BACKGROUND: In cross-sectional studies, the aldosterone-to-renin ratio (ARR) has been reported to be associated with hypertension under conditions of higher sodium intake. The objective of this prospective study was to investigate the association between ARR and the development of hypertension in community residents stratified by dietary sodium intake. METHODS: From the general population of Ohasama, we obtained plasma renin activity (PRA) and plasma aldosterone concentrations (PACs) for 608 participants (mean age = 57.6 years; 71.4% women) without hypertension at baseline. Using the Cox model, we computed the adjusted hazard ratio (HR) of natural log-transformed ARR (lnARR) for the development of hypertension, defined as blood pressure ≥140/90mm Hg or start of treatment with antihypertensive drugs during follow-up. RESULTS: During a mean follow-up of 6.8 years, 298 participants developed hypertension. The median PRA, PAC, and ARR were 1.2ng/ml/hour, 6.6ng/dl, and 5.5ng/dl per ng/ml/hour, respectively. Each 1 SD increase in lnARR was associated with an increased risk for the development of hypertension in participants overall (HR = 1.18; P = 0.007). In participants with higher sodium intake (median ≥4,102mg/day), a significant association of lnARR with hypertension remained (HR = 1.25; P = 0.009), whereas no significant association was observed in participants with lower sodium intake (P = 0.18). Participants who developed hypertension had significantly lower PRA than those who did not (P = 0.003), despite no differences in PAC (P = 0.91). CONCLUSIONS: These results raise the hypothesis that relative aldosterone excess may have a deleterious effect on the development of hypertension by contributing to salt/volume-related hypertension.

Day-to-day variability in home blood pressure is associated with cognitive decline: the Ohasama study.

Although an association between high blood pressure and cognitive decline has been reported, no studies have investigated the association between home blood pressure and cognitive decline. Home blood pressure measurements can also provide day-to-day blood pressure variability calculated as the within-participant SD. The objectives of this prospective study were to clarify whether home blood pressure has a stronger predictive power for cognitive decline than conventional blood pressure and to compare the predictive power of the averaged home blood pressure with day-to-day home blood pressure variability for cognitive decline. Of 485 participants (mean age, 63 years) who did not have cognitive decline (defined as Mini-Mental State Examination score, <24) initially, 46 developed cognitive decline after a median follow-up of 7.8 years. Each 1-SD increase in the home systolic blood pressure value showed a significant association with cognitive decline (odds ratio, 1.48; P=0.03). However, conventional systolic blood pressure was not significantly associated with cognitive decline (odds ratio, 1.24; P=0.2). The day-to-day variability in systolic blood pressure was significantly associated with cognitive decline after including home systolic blood pressure in the same model (odds ratio, 1.51; P=0.02), whereas the odds ratio of home systolic blood pressure remained positive, but it was not significant. Home blood pressure measurements can be useful for predicting future cognitive decline because they can provide information not only on blood pressure values but also on day-to-day blood pressure variability.

Expression of (pro)renin receptor in breast cancers and its effect on cancercell proliferation.

(Pro)renin receptor ((P)RR) is a specific receptor for renin and prorenin. The aim of the present study is to clarify expression of (P)RR and pathophysiological roles of (P)RR in human breast carcinomas. (P)RR expression was studied in 69 clinical cases of breast carcinoma by immunohistochemistry.Effects of (P)RR on cell proliferation were examined in cultured human breast carcinoma cells using (P)RR specific small interference RNA. Immunohistochemistry showed that(P)RR immunoreactivity was detected in the breast carcinoma cells in 50 of 69 cases of breast carcinoma (72%). The analysis on association between (P)RR immunoreactivity and clinicopathological parameters showed that the number of (P)RR positive cases was significantly greater in Ki-67 (a cell proliferation marker)≥10% group than in Ki-67<10% group (P=0.02). (P)RR was expressed in 4 types of human breast carcinoma cell lines. (P)RR specific small interference RNA inhibited proliferation of both MCF-7 (ERα positive) and SK-BR-3 (ERα negative) cells. The present study has shown, for the first time, the expression of (P)RR in human breast carcinoma tissues and cultured breast carcinoma cell lines. These findings have raised the possibility that the blockade of the (P)RR signaling may be a novel therapeutic strategy against breast carcinomas.

Aldosterone-to-renin ratio and nocturnal blood pressure decline assessed by self-measurement of blood pressure at home: the Ohasama Study.

Based on ambulatory blood pressure (BP) monitoring, the aldosterone-to-renin ratio (ARR) has been reported to be associated with a diminished nocturnal decline in BP, generally referred to as a "non-dipping" pattern. The objective of this cross-sectional study was to investigate the association between ARR and the non-dipping pattern based on home BP measurements. This study included 177 participants≥55 years from the general population of Ohasama (mean age: 67.2 years; 74.6% women); no patient was receiving antihypertensive treatment. The median plasma renin activity (PRA), plasma aldosterone concentration (PAC) and ARR were 0.8 ng/mL/h, 8.1 ng/dL and 9.7 ng/dL per ng/mL/h, respectively. Each 1 SD increase in log-transformed (ln) ARR was significantly associated with the prevalence of the non-dipping pattern after adjustments for possible confounding factors including home morning systolic BP (odds ratio, 1.45; p=0.049). However, no significant associations of PRA or PAC with the non-dipping pattern were observed (p≥0.2). When participants were divided into four groups according to median levels of home morning and night-time systolic BPs, the group with a higher home morning systolic BP (≥128.4 mmHg) with a higher home night-time systolic BP (≥114.4 mmHg) had the greatest ARR levels (ANCOVA p=0.01). These results support the hypothesis that relative aldosterone excess may be related to a non-dipping pattern in a general population and suggest that a non-dipping pattern can be accurately observed by home BP measurements.

Plasma soluble (pro)renin receptor is independent of plasma renin, prorenin, and aldosterone concentrations but is affected by ethnicity.

A soluble (pro)renin receptor (sPRR) circulates in plasma and is able to bind renin and prorenin. It is not known whether plasma sPRR concentrations vary with the activity of the renin-angiotensin system. We measured plasma sPRR, renin, prorenin, and aldosterone concentrations in 121 white and 9 black healthy subjects, 40 patients with diabetes mellitus, 41 hypertensive patients with or without renin-angiotensin system blockers, 9 patients with primary aldosteronism, and 10 patients with Gitelman syndrome. Median physiological plasma sPRR concentration was 23.5 ng/mL (interquartile range, 20.9-26.5) under usual uncontrolled sodium diet. sPRR concentration in healthy subjects, unlike renin and prorenin, did not display circadian variation or dependence on age, sex, posture, or hormonal status. sPRR concentrations were ≈25% lower in black than in white subjects, whereas renin concentrations were ≈40% lower. Patients with diabetes mellitus (average renin-high prorenin levels) and with hypertension only (average renin-average prorenin levels) had sPRR concentrations similar to healthy subjects. Renin-angiotensin system blockade was associated with increase of sPRR concentration by ≈12%. sPRR in patients with primary aldosteronism (low renin-low prorenin) and Gitelman syndrome (high renin-high prorenin) were similar and ≈10% higher than in healthy subjects. There was no correlation between sPRR and renin or prorenin. In conclusion, our results show that plasma sPRR concentrations are dependent on ethnicity and independent of renin, prorenin, and aldosterone concentrations in healthy subjects and in patients with contrasted degrees of renin-angiotensin system activity.

Night-time blood pressure is associated with the development of chronic kidney disease in a general population: the Ohasama Study.

OBJECTIVE: Ambulatory blood pressure (BP) is reportedly associated with target organ damage. However, whether ambulatory BP carries prognostic significance for the development of chronic kidney disease (CKD) has not been confirmed. METHOD: We measured ambulatory BP in 843 participants without CKD at baseline from a general Japanese population and examined the incidence of CKD defined as positive proteinuria or an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m at health checks. The association between baseline ambulatory BP and CKD incidence was examined using the Cox proportional hazard regression model adjusted for sex, age, BMI, habitual smoking, habitual alcohol consumption, diabetes mellitus, hypercholesterolemia, a history of cardiovascular disease, antihypertensive medication, eGFR at baseline, the number of follow-up examinations, and the year of the baseline examination. RESULTS: The mean age of the participants averaged 62.9 ±â€Š8.1 years, 71.3% were women and 23.7% were under antihypertensive medication. During a median follow-up of 8.3 years, 220 participants developed CKD events. The adjusted hazard ratios for CKD in a 1-standard deviation increase in daytime and night-time SBP were 1.13 [95% confidence interval (CI) 0.97-1.30] and 1.21 (95% CI 1.04-1.39), respectively. When night-time and daytime BP was mutually adjusted into the same model, only night-time BP persisted as an independent predictor of CKD. CONCLUSION: Night-time BP is a better predictor of CKD development than daytime BP in the general population. Ambulatory BP measurement is considered useful for evaluating the risk of progression to CKD.

Increased expression of (pro)renin receptor in aldosterone-producing adenomas.

(Pro)renin receptor ((P)RR) is a specific receptor for renin and prorenin. The aim of the present study is to clarify expression and possible pathophysiological roles of (P)RR in aldosterone-producing adenomas (APAs) and other adrenal tumors. Expression of (P)RR was studied by immunocytochemistry, western blot analysis and real-time RT-PCR in adrenal tumor tissues obtained at surgery. Immunocytochemistry showed that (P)RR was expressed in normal adrenal glands and tumor tissues of adrenocortical tumors including APAs. In the normal adrenal glands, positive (P)RR immunostaining was observed in both adrenal cortex and medulla, with higher (P)RR immunostaining observed in zona glomerulosa and zona reticularis. Positive (P)RR immunostaining was also observed in the adrenocortical tumors, with elevated (P)RR immunostaining found in APAs, particularly in compact cells. By contrast, no apparent (P)RR immunostaining was observed in pheochromocytomas. Western blot analysis showed a band of (P)RR protein in normal adrenal glands and adrenocortical tumors at the position of 35 kDa. The relative expression levels of (P)RR protein were higher in tumor tissues of APAs than in attached non-neoplastic adrenal tissues of APAs. Real-time RT-PCR showed that expression levels of (P)RR mRNA were significantly increased in tumor tissues of APAs compared with other adrenal tumor tissues and attached non-neoplastic adrenal tissues of APAs. The present study has shown for the first time that expression of (P)RR is elevated in tumor tissues of APAs, raising the possibility that (P)RR may play pathophysiological roles in APAs, such as aldosterone secretion and cell proliferation.

In Situ Hybridization Method Reveals (Pro)renin Receptor Expressing Cells in the Pituitary Gland of Rats: Correlation with Anterior Pituitary Hormones.

Expression of (pro)renin receptor ((P)RR), a specific receptor for renin and prorenin, was studied in rat pituitary gland. In situ hybridization showed that cells expressing (P)RR mRNA were widely distributed in the anterior lobe and intermediate lobe of the pituitary gland. Double-staining using in situ hybridization for (P)RR mRNA and immunohistochemistry for the pituitary hormones showed that (P)RR mRNA was expressed in most of the GH cells and ACTH cells in the anterior lobe. (P)RR mRNA was also expressed in a few prolactin cells and TSH cells, but not in LH cells. The present study has shown for the first time the distribution of (P)RR mRNA expressing cells in the rat pituitary gland. These findings suggest that (P)RR plays physiological roles in the pituitary gland, such as the modulation of the pituitary hormone secretion.

Expression of (pro)renin receptor in human erythroid cell lines and its increased protein accumulation by interferon-γ.

The renin-angiotensin system is known to enhance erythropoiesis. (Pro)renin receptor ((P)RR), a specific receptor for renin and prorenin, has recently been identified. However, expression of (P)RR in erythroid cells has not been studied. The aim of the present study is to clarify expression of (P)RR in erythroid cells, and the effects of erythropoietin, angiotensin II, transforming growth factor-ß1 (TGF-ß1), interferon-γ (IFN-γ) and interleukin-1ß (IL-1ß) on its expression. Western blot analysis showed that (P)RR protein was expressed in human cultured erythroid cell lines, YN-1 and YN-1-0-A (a clonal variant cell line of YN-1). Erythropoietin (1IU/ml) increased (P)RR mRNA expression levels in YN-1-0-A cells (1.7-fold increase compared with control), but angiotensin II did not. Treatment of YN-1-0-A cells with IFN-γ (10ng/ml) for 48h increased the expression levels of (P)RR protein significantly (1.4-fold increase compared with control), whereas it had no significant effects on expression levels of (P)RR mRNA. Treatment of YN-1-0-A cells with TGF-ß1 or IL-1ß for 24 or 48h had no significant effects on expression levels of (P)RR. The present study has shown for the first time expression of (P)RR in erythroid cells, raising the possibility that (P)RR may have a role in erythropoiesis and the pathophysiology of certain types of anemia.

Biotin ameliorates muscle cramps of hemodialysis patients: a prospective trial.

Patients with renal failure undergoing hemodialysis often have muscle cramps during and after the dialysis therapy. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied with severe pain, resulting in early termination of a HD session and inadequate dialysis. The etiology of the cramps is unknown and effective anti-cramp medicine is not available. We have hypothesized that water-soluble vitamins are deficient in HD patients. Accordingly, we administrated biotin to 14 patients who had frequent muscle cramps during HD sessions. Oral administration of 1 mg/day biotin promptly reduced the onset and the severity of cramps in 12 patients both during and after HD. Then, the plasma biotin levels were measured by an enzyme-linked immunosorbent assay method (ELISA) in HD patients, including 14 patients with cramps and 13 patients without cramps, and 11 healthy volunteers. Plasma biotin levels were elevated in 27 HD patients at baseline compared with healthy volunteers [451 (377 - 649) vs. 224 (148 - 308) ng/l, median (lower-upper quartiles); p < 0.0001]. Unexpectedly, among the 14 cramp patients, the biotin levels were significantly higher in biotin-ineffective 7 patients than biotin-effective 7 patients [1,064 (710 - 1,187) vs. 445 (359 - 476) ng/l; p < 0.001]. Thus, the biotins measured by ELISA may consist of not only intact biotin but also its metabolites that do not function as a vitamin. In conclusion, biotin administration is one choice to relieve HD patients from muscle cramps regardless of their elevated plasma biotin levels.

Home blood pressure level, blood pressure variability, smoking, and stroke risk in Japanese men: the Ohasama study.

BACKGROUND: Hypertension and smoking independently contribute to the risk of stroke. Our objective was to investigate home blood pressure (HBP) levels, day-by-day BP variability, and smoking in the prediction of stroke in Japanese men. METHODS: In this study, 902 men (mean age, 58.6 years) without a past history of stroke were evaluated. HBP was measured once every morning for 4 weeks. Day-by-day BP variability was defined as within-subject standard deviations (SD) of HBP. Smoking history was obtained from a standardized questionnaire. Hazard ratios (HRs) for stroke were examined by Cox regression model, with adjustment for possible confounders. RESULTS: During 13.1 years (median) of follow-up, 89 cerebral infarctions, 28 intracranial hemorrhages, and six other strokes occurred. Systolic HBP levels (HR = 1.59 per 14.6 mm Hg increase, P < 0.0001) and variability (HR = 1.26 per 3.1 mm Hg increase, P = 0.03) of +1 between-subject SD were significantly associated with cerebral infarction. The relationship between HBP and cerebral infarction differed with smoking status (interaction P = 0.021 and 0.017 for systolic level and variability, respectively). In analyses stratified according to smoking, systolic level (HR = 1.78, P < 0.0001) and variability (HR = 1.38, P = 0.006) were significantly associated with cerebral infarction in ever smokers (N = 511), but not in never smokers (N = 391; P ≥ 0.6 for both). No significant association was found between smoking and the risk of intracranial hemorrhage. CONCLUSIONS: In ever smokers, both HBP levels and variability are significantly associated with the risk of cerebral infarction. Our findings further validate the benefit of smoking cessation in preventing cardiovascular disease (CVD), especially cerebral infarction.