Clinical characterization of patients with primary aldosteronism plus subclinical Cushing's syndrome.

BACKGROUND: Primary aldosteronism (PA) plus subclinical Cushing's syndrome (SCS), PASCS, has occasionally been reported. We aimed to clinically characterize patients with PASCS who are poorly profiled. METHODS: A population-based, retrospective, single-center, observational study was conducted in 71 patients (age, 58.2 ± 11.2 years; 24 males and 47 females) who developed PA (n = 45), SCS (n = 12), or PASCS (n = 14). The main outcome measures were the proportion of patients with diabetes mellitus (DM), serum potassium concentration, and maximum tumor diameter (MTD) on the computed tomography (CT) scans. RESULTS: The proportion of DM patients was significantly greater in the PASCS group than in the PA group (50.0% vs. 13.9%, p <  0.05), without a significant difference between the PASCS and SCS groups. Serum potassium concentration was significantly lower in the PASCS group than in the SCS group (3.2 ± 0.8 mEq/L vs. 4.0 ± 0.5 mEq/L; p <  0.01), without a significant difference between the PASCS and PA groups. Among the 3 study groups of patients who had a unilateral adrenal tumor, MTD was significantly greater in the PASCS group than in the PA group (2.7 ± 0.1 cm vs. 1.4 ± 0.1 cm; p <  0.001), without a significant difference between the PASCS and SCS groups. CONCLUSIONS: Any reference criteria were not obtained that surely distinguish patients with PASCS from those with PA or SCS. However, clinicians should suspect the presence of concurrent SCS in patients with PA when detecting a relatively large adrenal tumor on the CT scans.

Effects of dapagliflozin on renin-angiotensin-aldosterone system under renin-angiotensin system inhibitor administration.

Sodium-glucose cotransporter-2 inhibitors (SGLT2Is) are reported to prevent cardiovascular events by a mechanism possibly including diuresis and sodium excretion. In this respect, diuresis-induced compensatory upregulation of the renin-angiotensin-aldosterone (RAA) system should be clarified and we performed a randomized controlled trial using dapagliflozin, an SGLT2I. Hypertensive diabetic patients taking angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers were randomly assigned to a dapagliflozin group (DAPA) or a control group (CTRL) with the difference in the changes in plasma renin activity (PRA) after 24 weeks of the treatment as the primary outcome. PRA, plasma aldosterone concentration (PAC), age, sex, BMI, blood pressure, pulse rate, eGFRcys, and HbA1c were not different between the groups at baseline. After 24 weeks, the changes in the PRA from the baseline of the DAPA (n = 44) and CTRL (n = 39) groups were 6.30 ± 15.55 and 1.42 ± 11.43 ng/mL/h, respectively (p = 0.11) although the power of detection was too small. However, post hoc nonparametric analyses revealed that there was a definite increase in the PRA and PAC in the DAPA group (p < 0.0001 and p = 0.00025, respectively) but not in the CTRL group. The PRA in the DAPA group after 24 weeks treatment was significantly elevated compared to the CTRL group (p = 0.013) but not for the PAC. Accordingly, it would be suggested that dapagliflozin may not induce a profound increase, if any, in PAC after 24 weeks of treatment in hypertensive type 2 diabetic patients under RAA suppression.

[Bone and Calcium Research Update 2015. Intracellular Ca2+ regulation in endothelial cells].

Endothelial cells regulates vascular tonus and exerts anti-atherosclerotic effects in response to external stimulation via Ca2+-dependent production of vasoactive substances such as NO. Agonists such as ATP hydrolyze membrane PIP2 and release soluble IP3 into the cell. IP3 then binds to the IP3 receptor and mobilizes Ca2+ from endoplasmic reticulum Ca2+ stores, followed by Ca2+ influxes from the extracellular space. Such store-operated Ca2+ entry comprises organization of a Ca2+ signal complex at the local subplasmalemmal domain involving TRPC4, caveolin1, and STIM1, a Ca2+ sensor protein for intracellular Ca2+ stores. Genetic deletion of any component of these three proteins can lead to depressed Ca2+ influxes and changes of endothelial function. Further elucidation of spatiotemporally organized endothelial Ca2+ signaling is critical for understanding pathophysiology of cardiovascular diseases.

Comparison of the antialbuminuric effects of benidipine and hydrochlorothiazide in Renin-Angiotensin System (RAS) inhibitor-treated hypertensive patients with albuminuria: the COSMO-CKD (COmbination Strategy on Renal Function of Benidipine or Diuretics TreatMent with RAS inhibitOrs in a Chronic Kidney Disease Hypertensive Population) study.

OBJECTIVE: This study evaluated the non-inferiority of renoprotection afforded by benidipine versus hydrochlorothiazide in hypertensive patients with chronic kidney disease (CKD). METHODS: In this prospective, multicenter, open-labeled, randomized trial, the antialbuminuric effects of benidipine and hydrochlorothiazide were examined in renin-angiotensin system (RAS) inhibitor-treated patients with blood pressure (BP) readings of ≥ 130/80 mmHg and ≤ 180/110 mmHg, a urinary albumin to creatinine ratio (UACR) of ≥ 300 mg/g, and an estimated glomerular filtration rate (eGFR) of ≥ 30 ml/min/1.73m(2). Patients received benidipine (n = 176, final dose: 4.8 mg/day) or hydrochlorothiazide (n = 170, 8.2 mg/day) for 12 months. RESULTS: Benidipine and hydrochlorothiazide exerted similar BP- and eGFR-decreasing actions. The UACR values for benidipine and hydrochlorothiazide were 930.8 (95% confidence interval: 826.1, 1048.7) and 883.1 (781.7, 997.7) mg/g at baseline, respectively. These values were reduced to 790.0 (668.1, 934.2) and 448.5 (372.9, 539.4) mg/g at last observation carried forward (LOCF) visits. The non-inferiority of benidipine versus hydrochlorothiazide was not demonstrated (benidipine/hydrochlorothiazide ratio of LOCF value adjusted for baseline: 1.67 (1.40, 1.99)). CONCLUSIONS: The present study failed to demonstrate the non-inferiority of the antialbuminuric effect of benidipine relative to that of hydrochlorothiazide in RAS inhibitor-treated hypertensive patients with macroalbuminuria.

Pheochromocytoma With High Adrenocorticotropic Hormone Production Capacity Without Pigmentation and Cushingoid Symptoms: A Case Report With a Literature Review.

Pheochromocytoma or paraganglioma (PPGL) originating from chromaffin cells can produce diverse hormones in addition to catecholamines, including adrenocorticotropic hormone (ACTH). In pheochromocytoma, high levels of ACTH might not result in pigmentation as typically observed in Addison's disease, and patients might not exhibit the symptoms of Cushing's syndrome, despite ACTH-dependent hypercortisolism. A 63-year-old male patient with hypertension was admitted to our facility, and computed tomography (CT) revealed a large right adrenal tumor. Despite high plasma ACTH (700-1300 pg/mL) and serum cortisol (90-100 µg/dL) levels, no physical pigmentation or Cushingoid symptoms were observed. Urinary metanephrine and normetanephrine levels reached as high as 16.0 mg and 3.2 mg, respectively. 123I-metaiodobenzylguanidine (MIBG) scintigraphy was negative. Low-dose dexamethasone paradoxically increased ACTH and cortisol levels, indicating the potential positive feedback regulation of both hormones by glucocorticoids. The patient was diagnosed with an ACTH-producing pheochromocytoma and underwent successful laparoscopic surgery to remove the adrenal tumor under the intravenous administration of a high-dose α-blocker and hydrocortisone. The levels of ACTH, cortisol, and urinary metanephrine/normetanephrine returned close to normal after tumor removal. We report a rare case of pheochromocytoma with extremely high ACTH/cortisol production but without pigmentation or Cushingoid symptoms. We also reviewed previous reports of ACTH-producing PPGL regarding the paradoxical regulation of ACTH/cortisol by glucocorticoids, pigmentation, Cushingoid symptoms, and negativity of 123I-MIBG scintigraphy.

A Pregnant Woman with Excess Vasopressinase-Induced Diabetes Insipidus Complicated by Central Diabetes Insipidus like Lymphocytic Infundibulo-Neurohypophysitis.

Background: Gestational diabetes insipidus (DI) is a very rare complication of pregnancy. We present a case of gestational DI combining two different types of DI. Case Presentation. A 39-year-old pregnant woman suddenly presented with thirst, polydipsia, and polyuria after 31 gestation weeks (GWs). Based on laboratory findings of hypotonic urine (78 mOsm/kgH2O) with higher plasma osmolality (298 mOsm/kgH2O) and higher serum sodium levels (149 mEq/L), gestational DI was suspected, and the clinical course was monitored without therapy until the results of a measurement of plasma arginine vasopressin (AVP) levels were available. However, she subsequently developed acute prerenal failure and underwent an emergency cesarean section at 34 GWs. Her resected placenta weighed 920 g, nearly twice the normal weight. Immediately following delivery, intranasal 1-desamino-8-D-arginine vasopressin was administered, and her symptoms promptly disappeared. Afterward, her predelivery plasma AVP level was found to have been inappropriately low (0.7 pg/mL) given her serum sodium level. The patient's serum vasopressinase level just before delivery was 2,855 ng/mL, more than 1,000 times the upper limit of the normal range, suggesting excess vasopressinase-induced DI. The presence of anti-rabphilin-3A antibodies in the patient's blood, a hypertonic saline infusion test result, and loss of the high-intensity signal of the posterior pituitary on fat-suppressed T1-weighted magnetic resonance images without thickening of the stalk and enlargement of the neurohypophysis suggested concurrent central DI-like lymphocytic infundibulo-neurohypophysitis (LINH). Conclusion: In addition to the degradation of AVP by excess placental vasopressinase due to the enlarged placenta, an insufficient compensatory increase in AVP secretion from the posterior pituitary gland due to LINH-like pathogenesis might have led to DI symptoms.

Impaired flow-dependent control of vascular tone and remodeling in P2X4-deficient mice.

The structure and function of blood vessels adapt to environmental changes such as physical development and exercise. This phenomenon is based on the ability of the endothelial cells to sense and respond to blood flow; however, the underlying mechanisms remain unclear. Here we show that the ATP-gated P2X4 ion channel, expressed on endothelial cells and encoded by P2rx4 in mice, has a key role in the response of endothelial cells to changes in blood flow. P2rx4(-/-) mice do not have normal endothelial cell responses to flow, such as influx of Ca(2+) and subsequent production of the potent vasodilator nitric oxide (NO). Additionally, vessel dilation induced by acute increases in blood flow is markedly suppressed in P2rx4(-/-) mice. Furthermore, P2rx4(-/-) mice have higher blood pressure and excrete smaller amounts of NO products in their urine than do wild-type mice. Moreover, no adaptive vascular remodeling, that is, a decrease in vessel size in response to a chronic decrease in blood flow, was observed in P2rx4(-/-) mice. Thus, endothelial P2X4 channels are crucial to flow-sensitive mechanisms that regulate blood pressure and vascular remodeling.

Differences in the birthweight of infants born to patients with early- or mid-to-late-detected gestational diabetes mellitus who underwent guideline-based glycemic control.

AIMS: To examine the effects of strict glycemic control on the birthweight of infants born to Japanese patients with early- or mid-to-late-detected gestational diabetes mellitus (ed- or md-GDM). METHODS: We retrospectively examined the characteristics of 101 patients with GDM who underwent guideline-based glycemic control. A 75-g oral glucose tolerance test was conducted to diagnose GDM at gestational weeks 11-15 (ed-GDM subgroup) and 24-28 (md-GDM subgroup). RESULTS: Infant birthweight was significantly lower in the ed-GDM subgroup (n = 25) than in the md-GDM subgroup (n = 76) (2688.3 ±â€¯470.4 g vs. 3052.4 ±â€¯383.1 g, p < 0.05), and the proportion of low-birthweight infants (<2500 g) was significantly higher in the ed-GDM subgroup than in the md-GDM subgroup (32.0% vs. 5.3%, p < 0.005). Fasting plasma glucose (FPG) levels during early treatment and before delivery were significantly lower in the ed-GDM subgroup than in the md-GDM subgroup (76.1 ±â€¯10.4 mg/dL vs. 85.5 ±â€¯9.6 mg/dL, p < 0.001; 80.5 ±â€¯10.4 mg/dL vs. 90.4 ±â€¯10.3 mg/dL, p < 0.0001). CONCLUSIONS: Patients with ed-GDM showed significantly lower FPG levels during treatment compared to those with md-GDM, presumably indicating an association with the delivery of low-birthweight infants.

Targeting of neutral cholesterol ester hydrolase to the endoplasmic reticulum via its N-terminal sequence.

Neutral cholesterol ester hydrolase (NCEH) accounts for a large part of the nCEH activity in macrophage foam cells, a hallmark of atherosclerosis, but its subcellular localization and structure-function relationship are unknown. Here, we determined subcellular localization, glycosylation, and nCEH activity of a series of NCEH mutants expressed in macrophages. NCEH is a single-membrane-spanning type II membrane protein comprising three domains: N-terminal, catalytic, and lipid-binding domains. The N-terminal domain serves as a type II signal anchor sequence to recruit NCEH to the endoplasmic reticulum (ER) with its catalytic domain within the lumen. All of the putative N-linked glycosylation sites (Asn(270), Asn(367), and Asn(389)) of NCEH are glycosylated. Glycosylation at Asn(270), which is located closest to the catalytic serine motif, is important for the enzymatic activity. Cholesterol loading by incubation with acetyl-LDL does not change the ER localization of NCEH. In conclusion, NCEH is targeted to the ER of macrophages, where it hydrolyzes CE to deliver cholesterol for efflux out of the cells.

Dietary phosphorus acutely impairs endothelial function.

Excessive dietary phosphorus may increase cardiovascular risk in healthy individuals as well as in patients with chronic kidney disease, but the mechanisms underlying this risk are not completely understood. To determine whether postprandial hyperphosphatemia may promote endothelial dysfunction, we investigated the acute effect of phosphorus loading on endothelial function in vitro and in vivo. Exposing bovine aortic endothelial cells to a phosphorus load increased production of reactive oxygen species, which depended on phosphorus influx via sodium-dependent phosphate transporters, and decreased nitric oxide production via inhibitory phosphorylation of endothelial nitric oxide synthase. Phosphorus loading inhibited endothelium-dependent vasodilation of rat aortic rings. In 11 healthy men, we alternately served meals containing 400 mg or 1200 mg of phosphorus in a double-blind crossover study and measured flow-mediated dilation of the brachial artery before and 2 h after the meals. The high dietary phosphorus load increased serum phosphorus at 2 h and significantly decreased flow-mediated dilation. Flow-mediated dilation correlated inversely with serum phosphorus. Taken together, these findings suggest that endothelial dysfunction mediated by acute postprandial hyperphosphatemia may contribute to the relationship between serum phosphorus level and the risk for cardiovascular morbidity and mortality.

Induction and activation of the transcription factor NFATc1 (NFAT2) integrate RANKL signaling in terminal differentiation of osteoclasts.

Signaling by RANKL is essential for terminal differentiation of monocytes/macrophages into osteoclasts. The TRAF6 and c-Fos signaling pathways both play important roles downstream of RANKL. We show here that RANKL selectively induces NFATc1 expression via these two pathways. RANKL also evokes Ca(2+) oscillations that lead to calcineurin-mediated activation of NFATc1, and therefore triggers a sustained NFATc1-dependent transcriptional program during osteoclast differentiation. We also show that NFATc1-deficient embryonic stem cells fail to differentiate into osteoclasts in response to RANKL stimulation, and that ectopic expression of NFATc1 causes precursor cells to undergo efficient differentiation without RANKL signaling. Thus, NFATc1 may represent a master switch for regulating terminal differentiation of osteoclasts, functioning downstream of RANKL.

Mineralocorticoid receptor blockade suppresses dietary salt-induced ACEI/ARB-resistant albuminuria in non-diabetic hypertension: a sub-analysis of evaluate study.

Excessive dietary salt intake can counteract the renoprotective effects of renin-angiotensin system (RAS) blockade in hypertensive patients with chronic kidney disease (CKD). In rodents, salt loading induces hypertension and renal damage by activating the mineralocorticoid receptor (MR) independently of plasma aldosterone levels. Thus, high salt-induced resistance to RAS blockade may be mediated by MR activation. To test this, a post hoc analysis of the Eplerenone Combination Versus Conventional Agents to Lower Blood Pressure on Urinary Antialbuminuric Treatment Effect (EVALUATE) trial was conducted. Thus, 304 non-diabetic hypertensive patients on RAS-blocking therapy were divided into tertiles according to salt intake (estimated 24-h urinary sodium excretion at baseline) and compared in terms of percent reduction in urinary albumin-to-creatinine ratio (UACR) at 52 weeks relative to baseline. The eplerenone-treated patients in the highest sodium excretion tertile exhibited significantly greater reduction in UACR than the placebo subjects in the same tertile (-22.5% vs. +21.8%, p = 0.02). This disparity was not observed in the lowest (-10.2% vs. -0.84%, p = 0.65) or middle (-19.5% vs. +9.5%, p = 0.22) tertiles. Similar systolic blood pressure changes were observed. In the whole cohort, reduction in UACR correlated positively with reduction in systolic blood pressure (r2 = 0.04, p = 0.02). These results support the hypothesis that excessive salt intake can enhance resistance to RAS blockade by activating MR. They also suggest that eplerenone plus RAS blockade may be effective for CKD in hypertensive patients, especially those with excessive salt intake.

Weight control before and during pregnancy for patients with gestational diabetes mellitus.

AIMS/INTRODUCTION: The aim of the present study was to examine the associations of pregestational body mass index (BMI) and gestational weight change with birthweight for gestational age in Japanese mothers with gestational diabetes mellitus (GDM). MATERIALS AND METHODS: We retrospectively examined the clinical and laboratory characteristics of 101 mothers with GDM (pregestational BMI 24.7 ± 5.8 kg/m2 ; maternal age at delivery 34.7 ± 5.1 years; gestational age 38.5 ± 1.4 weeks) at a single center from January 2011 to December 2016. RESULTS: Gestational weight changes were 6.22 ± 5.39 kg, and infant birthweights were 2,987.3 ± 393.6 g. Multivariable analysis showed that, in all mothers, pregestational BMI and gestational weight change were positively associated with infant birthweight (P < 0.001 and P = 0.007, respectively). Pregestational BMI, but not gestational weight change, was positively associated with infant birthweight (P = 0.007) in 31 mothers with GDM who had pregestational BMI ≥25 kg/m2 ; in 68 mothers with GDM who had pregestational BMI 18.5-24.9 kg/m2 , only gestational weight gain was positively associated with infant birthweight (P = 0.039). Two mothers had pregestational BMI <18.5 kg/m2 . No statistically significant interactions of pregestational BMI with gestational weight change were found (P = 0.158). CONCLUSIONS: In mothers with GDM, pregestational BMI ≥25 kg/m2 and excessive gestational weight gain were significantly associated with increased infant birthweight. A prospective multicenter clinical study enrolling a larger number of mothers with GDM will be required to verify the effects of adequately controlling pregestational and gestational weights on infant birthweight for gestational age.

Aldosterone enhances ligand-stimulated nitric oxide production in endothelial cells.

Chronic and acute actions of aldosterone have been shown recently to directly affect the cardiovascular system. However, it is unclear whether the acute effects of aldosterone on vasculature are constrictive or dilatory. Here, to clarify the nongenomic effects of aldosterone on endothelial function, we examined the effects of aldosterone on nitric oxide (NO) production in cultured endothelial cells (ECs) and on vascular tone. The intracellular NO production of bovine aortic ECs loaded with DAF-2 was determined using confocal microscopy. Accumulated NO in the culture medium was quantified by a microplate reader using membrane-impermeable DAF-2. Phosphorylation of endothelial NO synthase (eNOS) at Ser(1179) was assessed by Western blotting. Changes in intracellular Ca(2+) ([Ca(2+)](i)) were determined by confocal microscopy in ECs doubly loaded with fluo-4 and Fura Red. The effects of aldosterone, acetylcholine (ACh), and other signaling molecules on the tension of phenylephrine (PE)-contracted aortas of Sprague-Dawley rats were examined in an ex vivo organ bath chamber system. Short-term pre-exposure to aldosterone (1 x 10(-7) mol/L) enhanced ATP-induced NO production in ECs with increased phosphorylation of eNOS at Ser(1179). These effects were blocked by eplerenone, a mineralocorticoid receptor (MR) antagonist, and LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. Notably, aldosterone alone did not affect ATP-induced [Ca(2+)](i) changes or the Ser(1179) phosphorylation. Similarly, aldosterone (1 x 10(-8) to 1 x 10(-7) mol/L) did not affect the tone of rat aortas pre-contracted by PE, but enhanced ACh-induced vasorelaxation, which was again reversed by eplerenone or LY29400. In contrast, sodium nitroprusside-induced vasorelaxation in endothelium-denuded aortas was not affected by aldosterone. Thus, aldosterone acutely enhances ligand-mediated endothelial NO production by eplerenone-sensitive mechanisms involving a PI3K that may synergize Ca(2+)-dependent eNOS phosphorylation at Ser(1179).

Up-regulation of JAM-1 in AR42J cells treated with activin A and betacellulin and the diabetic regenerating islets.

Pancreatic AR42J cells demonstrate the pluripotency in precursor cells of the gut endoderm and also provide an excellent model system to study the differentiation of the pancreas. Using the mRNA differential display technique, we identified junctional adhesion molecule-1 (JAM-1), a component of the tight junction, was highly up-regulated during the differentiation of AR42J cells, although junctions were not formed. The expression level of JAM-1 showed an up-regulation in the mRNA level after 3 hours and in the protein level after 24 hours in [activin A + betacellulin]-treated AR42J cells. The expressions of its signaling molecules, PAR-3 and atypical PKC lambda, also increased after the addition of activin A + betacellulin. When JAM-1 was over-expressed in [activin A + betacellulin]-treated AR42J cells, tagged-JAM-1 was observed in cytoplasm as vesicular structures and JAM-1 was colocalized with Rab3B and Rab13, members of the Rab family expressed at tight junctions. In streptozotocin-induced regenerating islets, the expression of JAM-1 was also up-regulated in the mRNA level and the protein level. JAM-1 might therefore play an important role in the differentiation of AR42J cells and the regeneration of pancreatic islets.

Stromal interaction molecule 1 modulates blood pressure via NO production in vascular endothelial cells.

In vascular endothelial cells, store-operated calcium entry (SOCE) activates endothelial NO synthase (eNOS) and regulates nitric oxide (NO) production as well as flow-dependent mechanical stimuli. Stromal interaction molecule 1, or STIM1, was recently identified to be essential for SOCE, acting as a calcium sensor for intracellular calcium stores. However, how STIM1 affects endothelial function and blood pressure (BP) remains unclear. We generated STIM1 fl/fl mice and vascular endothelial cell-specific STIM1 knockout mice using the Cre-loxP system, and conducted experiments using these mice to clarify the physiological role of STIM1 in vascular endothelial function and BP as follows: (1) SOCE was analyzed in isolated aortic endothelial cells by calcium add-back with fluorescent Ca2+ indicators. Phosphorylation of eNOS and NO production were evaluated by immunoblotting and the NO indicator, respectively. (2) Tension of aortic rings was measured in 10-week-old mice in response to acetylcholine. (3) BP was measured in 10-week-old mice by the telemetry system. The results were: (1) SOCE, eNOS activation, and NO production were suppressed by ~50-60% in endothelial cells from STIM1 knockout. (2) Endothelium-dependent vasodilation was decreased in aortic rings from STIM1 knockout mice, whereas endothelium-independent relaxation was not altered. (3) STIM1 knockout mice exhibited significant BP elevation, especially in nighttime. (124.3 ± 2.5/99.2 ± 3.9 vs. 114.1 ± 3.2/83.6 ± 1.7 (nighttime, mmHg), 109.7 ± 1.7/83.0 ± 3.0 vs. 104.8 ± 3.3/73.7 ± 1.6 (daytime, mmHg), knockout vs. control, respectively). In conclusion, STIM1 in vascular endothelial cell modulates vascular function through NO production and has a major role in regulating BP, especially in the active time.

Administration of thiamazole for Graves' disease might trigger the onset of type 1 diabetes.

Thiamazole might trigger the onset of type 1 diabetes.

Caveolin-1 in extracellular matrix vesicles secreted from osteoblasts.

Caveolin-1 is an essential and signature protein of caveolae, which are small invaginations of the plasma membrane enriched in cholesterol and sphingolipids. Although high levels of expression of caveolin-1 have been demonstrated in osteoblasts as well as endothelial cells, fibroblasts, and muscular cells, the role of caveolin-1 in osteoblasts has not been clarified. Here, we show that caveolin-1 is secreted from osteoblasts in the form of matrix vesicles; extracellular vesicles released from the plasma membrane of osteoblasts. In this study, caveolae and matrix vesicles were similarly enriched in cholesterol and sphingomyelin in fractions isolated from mineralizing MC3T3-E1 cells. Interestingly, in the MC3T3-E1 cells caveolin-1 was enriched in the matrix vesicle fraction as well as the caveolar membrane fraction, and the amount of caveolin-1 in the matrix vesicle fraction increased as differentiation progressed. Localization of caveolin-1 in matrix vesicles was also confirmed in murine tibia. Furthermore, overexpression of caveolin-1 enhanced matrix calcification in MC3T3-E1 cells, whereas knockdown of caveolin-1 diminished it. These results suggest that secreted caveolin-1 as a component of matrix vesicles may play an important role in osteoblast calcification.

Subcortical Ca2+ waves sneaking under the plasma membrane in endothelial cells.

Subplasmalemmal Ca2+, dynamically equilibrated with extracellular Ca2+, affects numerous signaling molecules, effectors, and events within this restricted space. We demonstrated the presence of a novel Ca2+ wave propagating beneath the plasma membrane in response to acute elevation of extracellular [Ca2+], by targeting a Ca2+ sensor, cameleon, to the endothelial plasmalemma. These subcortical waves, spatially distinct from classical cytosolic Ca2+ waves, originated in localized regions and propagated throughout the subplasmalemma. Translocation of an expressed GFP fused with a PH domain of PLC from the plasma membrane to the cytosol accompanied these subcortical waves, and U73122 attenuated not only the GFP-PH translocation, but also the peak amplitude of the subcortical Ca2+ waves; this finding suggests the involvement of local IP3 production through PLC-mediated PIP2 hydrolysis in the initiation of these waves. Changes in NO production as well as PKCbeta-GFP translocation from the cytosol to the plasma membrane, but not of GFP-PLA2 to perinuclear endomembranes, were associated with the subplasmalemmal Ca2+ changes. Thus, extracellular Ca2+ maintains the basal PLC activity of the plasma membrane, is involved in the initiation of compartmentalized subcortical Ca2+ waves, and regulates Ca2+-dependent signaling molecules residing in or translocated to the plasma membrane. The full text of this article is available online at http://circres.ahajournals.org.

A High-Salt Diet Differentially Modulates Mechanical Activity of Afferent and Efferent Collecting Lymphatics in Murine Iliac Lymph Nodes.

BACKGROUND: The lymphatic system contributes to fluid homeostasis in various tissues. Recent evidence suggests that lymphangiogenesis induced by a high-salt diet (HSD) is associated with blood pressure regulation. Lymph nodes, located along lymphatic pathways, are not only important secondary lymphoid tissues for cancer metastasis, inflammation, and immune responses, but are also important for fluid homeostasis. Afferent lymphatics collect lymph from the pre-nodal area and efferent lymphatics drain lymph out of the lymph nodes. However, the difference in mechanical activity between afferent and efferent lymphatics and the effect of a HSD on these vessels have not been shown. METHODS AND RESULTS: Changes in mechanical activity of isolated afferent and efferent lymphatics in normal salt diet (NSD) and 4-week HSD mice in response to increases in intraluminal pressures from 3 to 7 cmH2O were measured using video-microscopy. The higher intramural pressure equivalently decreased pumping activity of afferent and efferent lymphatics in NSD mice. A HSD suppressed the amplitude, ejection fraction, and stroke volume of afferent lymphatics, leading to marked reductions in pumping activity. In contrast, the pumping activities of efferent lymphatics were resistant to a HSD and were preserved by enhancing the contraction frequency. CONCLUSIONS: A HSD differentially modulated the mechanical activity of afferent and efferent collecting lymphatics in murine iliac lymph nodes.