Evaluation of the enzymatic properties of DNA (cytosine-5)-methyltransferase M.ApeKI from archaea in the presence of metal ions.

We previously identified M.ApeKI from Aeropyum pernix K1 as a highly thermostable DNA (cytosine-5)-methyltransferase. M.ApeKI uses the type II restriction-modification system (R-M system), among the best-studied R-M systems. Although endonucleases generally utilize Mg (II) as a cofactor, several reports have shown that MTases exhibit different reactions in the presence of metal ions. This study aim was to evaluate the enzymatic properties of DNA (cytosine-5)-methyltransferase M.ApeKI from archaea in the presence of metal ions. We evaluated the influence of metal ions on the catalytic activity and DNA binding of M.ApeKI. The catalytic activity was inhibited by Cu (II), Mg (II), Mn (II), and Zn (II), each at 5 m m. DNA binding was more strongly inhibited by 5 m m Cu (II) and 10 m m Zn (II). To our knowledge, this is the first report showing that DNA binding of type II MTase is inhibited by metal ions.

Prevalence and causes of chronic cough in Japan.

BACKGROUND: Chronic cough is one of the most common symptoms of respiratory diseases and can adversely affect patients' quality of life and interfere with social activities, resulting in a significant social burden. A survey is required to elucidate the frequency and treatment effect of chronic cough. However, clinical studies that cover all of Japan have not yet been conducted. METHODS: Patients who presented with a cough that lasted longer than 8 weeks and visited the respiratory clinics or hospitals affiliated with the Japan Cough Society during the 2-year study period were registered. RESULTS: A total of 379 patients were enrolled, and those who did not meet the definition of chronic cough were excluded. A total of 334 patients were analyzed: 201 patients had a single cause, and 113 patients had two or more causes. The main causative diseases were cough variant asthma in 92 patients, sinobronchial syndrome (SBS) in 36 patients, atopic cough in 31 patients, and gastroesophageal reflux (GER)-associated cough in 10 patients. The time required to treat undiagnosed patients and those with SBS was significantly longer and the treatment success rate for GER-associated cough was considerably poor. CONCLUSIONS: We confirmed that the main causes of chronic cough were cough variant asthma, SBS, atopic cough, and their complications. We also showed that complicated GER-associated cough was more likely to become refractory. This is the first nationwide study in Japan of the causes and treatment effects of chronic cough.

A Case of Tumor Lysis Syndrome during Palliative Radiotherapy for Breast Cancer Metastases.

Tumor lysis syndrome (TLS) is the rapid disintegration of a malignant tumor treated with anticancer drugs or radiation, causing electrolyte abnormalities such as elevated uric acid levels, elevated potassium and phosphorus levels, and decreased calcium levels. These abnormalities can lead to hypotension, renal dysfunction, consciousness disorders, and even death in some cases. The current patient was a 65-year-old woman who had breast cancer with local invasion, lung metastasis, and bone metastasis from the time of the initial disease onset. Despite the administration of various chemotherapy and hormone therapy regimens, the tumor increased gradually, and at 2 years and 5 months after the initial onset, pain and bleeding from metastatic infiltration of the cervical lymph nodes were noted. Therefore, radiotherapy was indicated for palliation of pain and bleeding caused by metastatic invasion of the cervical lymph nodes. Irradiation (30 Gy/10fr) was planned with a 3-field technique using 4MVX and 10MVX. Approximately 11 h after the initial irradiation, symptoms such as respiratory distress, tachycardia, and hypotension were observed. Blood tests revealed hyperuricemia and hyperkalemia, leading to a diagnosis of TLS. Dialysis and electrolyte correction were immediately initiated resulting in normalization of electrolytes and stabilization of the blood pressure. It is crucial to understand that TLS is relatively rare but can occur after radiation therapy or in solid tumors, and warrants a prompt response if suspected based on symptoms or blood findings.

Effects of a 14-week community health program of exercise and learning/education in older adults: A single-arm pre-post comparison study.

This study was initiated in 2022 in Miyaki Town, Saga Prefecture, Japan, to determine the impact of an intervention that combined brain and physical function training and health education in older residents. Miyaki has a population of approximately 26,000, 35% of whom are considered to be aging. A 14-week program consisting of strength training, brain function training, and health lectures was conducted with 34 older residents of the community. Body composition, motor function, brain function, and various blood tests were evaluated before and after the intervention. Brain function was assessed using the Trail Making Test-A. Physical function was assessed by Open-Close Stepping, Functional Reach Test, Open-Leg Standing Time, and Two-Step Test. The intervention group showed significant improvements in brain function (p< 0.0001), physical function (p = 0.0037), body composition (p = 0.0053), and LDL-C (p = 0.017). This study provides substantial evidence that community-based combined programs can be beneficial for older adults.

Population Pharmacokinetic Model and Dosing Simulation of Meropenem Using Measured Creatinine Clearance for Patients with Sepsis.

PURPOSE: Creatinine clearance (CCr) and pharmacokinetic parameters are markedly affected by pathophysiological changes in patients with sepsis. However, only a few reports have assessed renal function in patients with sepsis using the measured CCr. Furthermore, the administration regimen has not been sufficiently evaluated using a population PK (PPK) model across renal function broad ranges. Therefore, this study was performed to construct a meropenem PPK model for patients with sepsis using the measured CCr and evaluate the optimized meropenem dosing regimen based on the CCr. METHODS: Patients with sepsis who received intravenous meropenem at the Showa University Hospital were enrolled in this prospective observational study. The PPK model was constructed using blood samples and clinical information of patients. The probability of target attainment (PTA) indicates the likelihood of achieving 50% time above the minimum inhibitory concentration (% T > MIC) based on 10,000 virtual patients using Monte Carlo simulations. The PTA for each meropenem regimen was 50% T > MIC based on different renal functions using the Monte Carlo simulation. RESULTS: One hundred samples were collected from 31 patients. The final PPK model incorporating the measured CCr as a covariate in CL displayed the best fit. The recommended dosing regimen to achieve a PTA of 50% T > MIC of 4 mcg/mL was 1 g every 8 hours as a 3-hour prolonged infusion for patients with CCr 85-130 mL/min and 1 g every 8 hours as an 8-hour continuous infusion for patients with CCr ≥ 130 mL/min. CONCLUSIONS: This model precisely predicted meropenem concentrations in patients with sepsis by accurately evaluating renal function using the measured CCr. Extended dosing was demonstrated to be necessary to achieve a PTA of 50% T > MIC for patients with CCr ≥ 85 mL/min. Meropenem effectiveness can be maximized in patients with sepsis by selecting the appropriate dosing regimen based on renal function and the MIC.

Impact of inhaled ciclesonide on asymptomatic or mild COVID-19: A randomized trial.

The aim of this study was to determine the efficacy and safety of ciclesonide in the treatment of novel coronavirus disease 2019 (COVID-19) as gauged by pneumonia progression. This multi-center, open-label randomized trial was conducted with patients recruited from 22 hospitals across Japan. Participants were patients admitted with mild or asymptomatic COVID-19 without signs of pneumonia on chest X-rays. Asymptomatic participants were diagnosed after identification through contact tracing. Trial participants were randomized to either the ciclesonide or control arm. Participants in the treatment arm were administered 400 µg of ciclesonide three times a day over seven consecutive days. The primary endpoint was exacerbated pneumonia within seven days. Secondary outcomes were changes in clinical findings, laboratory findings, and changes over time in the amount of the viral genome. In the treatment group, 16 patients (39.0%) were classified as having exacerbated pneumonia compared to 9 (18.8%) in the control group. The risk ratio (RR) was 2.08 (95% confidence interval (CI): 1.15-3.75), indicating a worsening of pneumonia in the ciclesonide group. Significant differences were noted in participants with a fever on admission (RR: 2.62, 90% CI: 1.17-5.85, 95% CI: 1.00-6.82) and individuals 60 years of age or older (RR: 8.80, 90% CI: 1.76-44.06, 95% CI: 1.29-59.99). The current results indicated that ciclesonide exacerbates signs of pneumonia on images in individuals with mild or asymptomatic symptoms of COVID-19 without worsening clinical symptoms.

Fetal Lung Cells Transfer Improves Emphysematous Change in a Mouse Model of Neutrophil Elastase-Induced Lung Emphysema.

Recently, several studies for lung regeneration have been reported. However, regenerating the lung tissue by the transfer of any cells directly to the lung has been hardly successful. The aim of this study was to evaluate the effect of fetal lung cells (FLCs) in a mouse model of lung emphysema. C57BL/6 mice were stimulated with neutrophil elastase (NE) intra-tracheally (i.t.) to generate lung emphysema. To collect fetal lung cells, C57BL/6-Tg (CAG-EGFP) mice were bred for 14 days. Before delivery, the bred mice were euthanized, and fetal lungs were harvested from the fetal mice and the cells were collected. The FLCs were transferred i.t. 24 h after the NE instillation. Four weeks after the NE instillation, mice were euthanized, and the samples were collected. The mean linear intercept (MLI) was significantly prolonged in the NE instillation group compared to the control group. However, in the FLCs transfer group stimulated with NE, the MLI became shorter than the NE-stimulated group without an FLCs transfer. This result shows that an FLCs transfer inhibited the progression of lung emphysema. Additionally, motility of the mice was also improved by the FLCs transfer. These results indicate that transfer of the FLCs, which were presumed to be progenitor cells for lung tissue, may improve the emphysematous change.

Serum cystatin C and CRP are early predictive biomarkers for emergence of hypoxia in COVID-19.

BACKGROUND: In Japan, during the coronavirus disease 2019 (COVID-19) pandemic, patients with non-hypoxia are recommended to recuperate at home or in pre-hospital facilities. However, it was observed that unexpected hypoxia may occur and become severe subsequently in patients whose symptoms were initially expected to improve naturally. The aim of this study is to validate biomarkers that can predict at an early stage the emergence of hypoxia in COVID-19 patients without hypoxia. METHODS: We retrospectively enrolled 193 patients with COVID-19, excluding patients with hypoxia and severe disease from the onset. Participants were classified into two groups according to the emergence of hypoxia during the clinical course, and the laboratory data were compared to identify biomarkers that could predict early the emergence of hypoxia. RESULTS: The areas under the curve for serum cystatin C (CysC) and C-reactive protein (CRP) levels for the emergence of hypoxia during the clinical course were higher than those for other biomarkers (CysC, 0.84 and CRP, 0.83). Multivariate analysis showed that high serum CysC and CRP levels were associated with the emergence of hypoxia during the clinical course. CONCLUSIONS: Elevated serum CysC and CRP levels were associated with the emergence of hypoxia during the clinical course in COVID-19 patients without hypoxia. These findings may help determine the need for hospitalization in initially non-hypoxic COVID-19 patients.

Serum IL-28A/IFN-λ2 is linked to disease severity of COVID-19.

Type III interferons (IFNs) play an important role in respiratory viral infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study aimed to determine whether the expression of serum type III IFNs predicted disease severity among patients with the coronavirus disease (COVID-19). A retrospective cohort study was conducted of patients admitted to a single hospital between March 21, 2020, and March 31, 2021. Patients were divided into mild to moderate I (MM) and moderate II to severe (MS) groups based on the COVID-19 severity classification developed by the Japanese Ministry of Health, Labor and Welfare. A total of 257 patients were included in the analysis. Human interleukin-28A (IL-28A/IFN-λ2) expression was significantly lower, and interleukin (IL)-6 expression was significantly higher in the MS group than in the MM group (both p < 0.001). In addition, IL-28A/IFN-λ2 was statistically significantly inversely correlated with the time from disease onset to negative SARS-CoV-2 PCR results (p = 0.049). Multivariable logistic regression analysis showed that IL-28A/IFN-λ2 was an independent predictor of disease severity (p = 0.021). The low expression of IL-28A/IFN-λ2 may serve as a serum biomarker that predicts the severity of COVID-19, possibly through the mechanism of delayed viral elimination.

Effects of Roxadustat on Erythropoietin Production in the Rat Body.

Anemia is a major complication of chronic renal failure. To treat this anemia, prolylhydroxylase domain enzyme (PHD) inhibitors as well as erythropoiesis-stimulating agents (ESAs) have been used. Although PHD inhibitors rapidly stimulate erythropoietin (Epo) production, the precise sites of Epo production following the administration of these drugs have not been identified. We developed a novel method for the detection of the Epo protein that employs deglycosylation-coupled Western blotting. With protein deglycosylation, tissue Epo contents can be quantified over an extremely wide range. Using this method, we examined the effects of the PHD inhibitor, Roxadustat (ROX), and severe hypoxia on Epo production in various tissues in rats. We observed that ROX increased Epo mRNA expression in both the kidneys and liver. However, Epo protein was detected in the kidneys but not in the liver. Epo protein was also detected in the salivary glands, spleen, epididymis and ovaries. However, both PHD inhibitors (ROX) and severe hypoxia increased the Epo protein abundance only in the kidneys. These data show that, while Epo is produced in many tissues, PHD inhibitors as well as severe hypoxia regulate Epo production only in the kidneys.

Comprehensive Gene Expression Signature Using RNA-Seq in Airways of Mouse Model of Severe Asthma with Fungal Sensitization.

INTRODUCTION: Inhalation of fungal allergens induces airway epithelial damage following airway inflammation and excessive mucus secretion, which can lead to severe asthma with fungal sensitization (SAFS). Comprehensive gene expression analysis in Alternaria-exposed mouse airways, a model of SAFS, has not been conducted. METHODS: BALB/c mice received intranasal administration of Alternaria extract or phosphate-buffered saline twice a week for 6 weeks. Lung sections and bronchoalveolar lavage fluid were obtained to assess airway inflammation. RNA-Seq in the central airway was performed, and gene ontology (GO) analysis and gene set enrichment analysis (GSEA) were conducted for pathway analyses. An in vitro experiment using human airway epithelial cell 16HBE14o- was performed to validate the RNA-Seq findings. RESULTS: Eosinophilic airway inflammation with mucus overproduction and airway remodeling was observed in mice exposed to Alternaria. RNA-Seq analysis revealed 403 upregulated and 108 downregulated genes in airways of Alternaria-exposed mice. In GO analysis, the functions of immunoglobulin (Ig) receptor binding, Ig production, inflammatory response, and T-cell activation were upregulated, while those of keratinization and defense response to other organisms were downregulated. GSEA revealed positive enrichment in T-cell receptor complex, immunological synapse, antigen binding, mast cell activation, and Ig receptor binding, and negative enrichment in keratinization and cornification in Alternaria-exposed mice relative to control. Alternaria exposure to 16HBE14o- cells validated the downregulation of epithelial keratinization-related genes, including SPRR1A, SPRR1B, and KRT6B. CONCLUSION: RNA-Seq analysis showed that Alternaria exposure induced inflammatory response and impaired defense mechanisms in mice airway epithelium, which might be therapeutic targets for SAFS.

Pathophysiological relevance of sputum MUC5AC and MUC5B levels in patients with mild asthma.

BACKGROUND: Airway mucus hypersecretion is an important pathophysiological feature of asthma. MUC5AC and MUC5B are the major secreted polymeric mucins in airways, and their compositions affect mucus properties. Despite the increasing appreciation of MUC5AC and MUC5B compositions in asthmatic airways, their pathophysiological relevance remains to be fully understood in humans. METHODS: In this cross-sectional study, we prospectively enrolled newly referred steroid-untreated patients with mild asthma and healthy controls. We compared induced sputum MUC5AC and MUC5B levels between patients and controls. Subsequently, we assessed the correlation between MUC5AC and MUC5B levels and clinical indices in patients. Sputum MUC5AC and MUC5B levels were measured using enzyme-linked immunosorbent assays. RESULTS: Sputum MUC5AC and MUC5B levels were significantly higher in patients (n = 87) than in controls (n = 22) (p = 0.0002 and p = 0.006, respectively). The ratio of sputum MUC5AC to MUC5B tended to be higher in patients than in controls (p = 0.07). Sputum MUC5AC levels significantly and positively correlated with fractional exhaled nitric oxide at expiratory flow of 50 mL/s (Spearman's rho = 0.29, p = 0.006), sputum eosinophil proportion (rho = 0.34, p = 0.0013), and airway sensitivity (rho = 0.39, p = 0.0005). By contrast, sputum MUC5B levels significantly and positively correlated with airway sensitivity (rho = 0.35, p = 0.002) and negatively correlated with airway reactivity (rho = -0.33, p = 0.004). CONCLUSIONS: Sputum MUC5AC is increased by protein levels and involved in airway type 2/eosinophilic inflammation and airway hyperresponsiveness in steroid-untreated patients with mild asthma.

Characteristics of and reasons for patients with chronic obstructive pulmonary disease to continue smoking, quit smoking, and switch to heated tobacco products.

INTRODUCTION: Smoking is the leading cause of chronic obstructive pulmonary disease (COPD), and smoking cessation is the most effective treatment for patients with COPD. However, few studies have investigated the continuation/cessation of smoking and heated tobacco products (HTP) in patients with COPD. The objective of this study was to examine the characteristics of patients with COPD, those who are current smokers and those who switched from cigarettes to HTP, and to examine the reason for the continuation or cessation of smoking. METHODS: This multicenter, cross-sectional study included 411 outpatients with COPD. Data for this study were part of a study conducted for a comprehensive evaluation of the smoking status and clinical factors in patients with COPD and their families. RESULTS: Logistic regression analysis revealed that a younger age, longer duration of smoking, fewer daily cigarettes, and lower modified Medical Research Council (mMRC) dyspnea score, and a lower Simplified Nutritional Appetite Questionnaire (SNAQ) score for appetite, were characteristics of current smokers (age OR=0.94; duration of smoking OR=1.07; number of cigarettes per day OR=0.94; mMRC OR=0.68; SNAQ OR=0.83; p<0.05). The logistic regression analysis model showed that a younger age and higher education level were associated with the use of HTP (age OR=0.83; higher education level OR=4.63; p<0.05). Many of the current smokers displayed smoking behaviors that are not guaranteed to be safe, such as reducing smoking or switching to lighter cigarettes or HTP. CONCLUSIONS: Patients with COPD who continue smoking tended to have low appetite as well as smoking behaviors that are not guaranteed to be safe. Physicians should provide appropriate guidance to these patients on smoking cessation.

Salt-Sensitive Hypertension of the Renal Tubular Cell-Specific NFAT5 (Nuclear Factor of Activated T-Cells 5) Knockout Mice.

[Figure: see text].

Effects of Angiotensin II on Erythropoietin Production in the Kidney and Liver.

The kidney is a main site of erythropoietin production in the body. We developed a new method for the detection of Epo protein by deglycosylation-coupled Western blotting. Detection of deglycosylated Epo enables the examination of small changes in Epo production. Using this method, we investigated the effects of angiotensin II (ATII) on Epo production in the kidney. ATII stimulated the plasma Epo concentration; Epo, HIF2α, and PHD2 mRNA expression in nephron segments in the renal cortex and outer medulla; and Epo protein expression in the renal cortex. In situ hybridization and immunohistochemistry revealed that ATII stimulates Epo mRNA and protein expression not only in proximal tubules but also in collecting ducts, especially in intercalated cells. These data support the regulation of Epo production in the kidney by the renin-angiotensin-aldosterone system (RAS).

Guaiazulene derivative 1,2,3,4-tetrahydroazuleno[1,2-b] tropone reduces the production of ATP by inhibiting electron transfer complex II.

Molecularly targeted therapy has been used for treatment of various types of cancer. However, cancer cells often acquire resistance to molecularly targeted drugs that inhibit specific molecular abnormalities, such as constitutive activation of kinases. Even in cancer cells that have acquired resistance, enhanced anabolism, including the synthesis of nucleotides, amino acids and lipids, is common to normal cancer cells. Therefore, there is a renewed interest in effectively eliminating cancer cells by specifically targeting their abnormal energy metabolism. Multiple strategies are currently being developed for mitochondrial-targeted cancer therapy, with agents targeting oxidative phosphorylation, glycolysis, the tricarboxylic acid cycle and apoptosis. In this study, we found that one of the guaiazulene derivatives, namely, 1,2,3,4-tetrahydroazuleno[1,2-b] tropone (TAT), inhibited the proliferation of cancer cell lines stronger than that of normal cells. In addition, we showed that TAT inhibited energy production in cancer cell lines, resulting in apoptosis. Analyses done in cancer cell lines and in the animal model Caenorhabditis elegans suggested that TAT acts on the mitochondrial electron transfer complex II and suppresses cellular energy production by inhibiting oxidative phosphorylation across species. These results suggest that TAT could represent a novel anticancer agent that selectively targets mitochondria.

Downregulation of type III interferons in patients with severe COVID-19.

Coronavirus disease 2019 (COVID-19) is globally rampant, and to curb the growing burden of this disease, in-depth knowledge about its pathophysiology is needed. This was an observational study conducted at a single center to investigate serum cytokine and chemokine levels of COVID-19 patients, based on disease severity. We included 72 consecutive COVID-19 patients admitted to our hospital from March 21 to August 31, 2020. Patients were divided into Mild-Moderate I (mild) and Moderate II-Severe (severe) groups based on the COVID-19 severity classification developed by the Ministry of Health, Labor and Welfare (MHLW) of Japan. We compared the patient characteristics as well as the serum cytokine and chemokine levels on the day of admission between the two groups. Our findings indicated that the severe group had significantly higher levels of serum fibrinogen, d-dimer, lactate dehydrogenase, C-reactive protein, ferritin, Krebs von den Lungen-6, surfactant protein (SP)-D, and SP-A than the mild group. Strikingly, the levels of interleukin (IL)-28A/interferon (IFN)-λ2 were significantly lower in the severe group than in the mild group. We believe that reduced levels of type III interferons (IFN-λs) and alterations in the levels of other cytokines and chemokines may impact the severity of the disease.

Multicentre Study on the Efficacy of Brachial Artery Transposition Among Haemodialysis Patients.

OBJECTIVE: Brachial artery transposition (BAT) is not a well known method for obtaining vascular access (VA) for maintenance haemodialysis. This study evaluated the outcomes of BAT. METHODS: This multicentre retrospective cohort study included 233 consecutive patients who underwent BAT between January 2012 and December 2013. The indications were inadequate vessels for obtaining VA, severe heart failure, hand ischaemia, central vein stenosis/occlusion, or a history of catheter/graft infection. The transposed brachial artery was used only for arterial inflow and other routes were used for outflow. RESULTS: BAT was successful in 227 patients, and adequate blood flow was achieved during dialysis sessions. The first successful cannulation was after a median of 18 days. BAT was performed using superficial veins as the return route in 127 patients and arteriovenous fistula (AVF) creation in 63 patients to prevent maturation failure. In 41 patients with central venous catheterisation, the transposed brachial artery was used for arterial inflow. The complications of BAT were impaired wound healing in 14 patients, including skin necrosis in two; large aneurysms in six, including a mycotic pseudo-aneurysm in one; arterial thrombosis in five; hand ischaemia in five; lymphorrhoea in four; and haematoma/bleeding in three. The transposed brachial artery was abandoned in four, three, three, and one case of arterial thrombosis/stenosis, haematoma/bleeding, skin necrosis, and large aneurysm, respectively. Access to the return routes failed in 48 cases because of vein damage caused by cannulation in 22, AVF thrombosis/stenosis in 14, catheter infection in six, and catheter occlusion in six. At two years, the primary patency rates of the transposed brachial artery and access circuit were 88% and 54%, respectively. CONCLUSION: BAT is a safe and effective technique. The patency was high for the transposed brachial artery but adequate for the access circuit. BAT can be considered for patients with an unobtainable standard arteriovenous access.

Regulation of Rhcg, an ammonia transporter, by aldosterone in the kidney.

Rhesus C glycoprotein (Rhcg), an ammonia transporter, is a key molecule in urinary acid excretion and is expressed mainly in the intercalated cells (ICs) of the renal collecting duct. In the present study we investigated the role of aldosterone in the regulation of Rhcg expression. In in vivo experiments using C57BL/6J mice, Western blot analysis showed that continuous subcutaneous administration of aldosterone increased the expression of Rhcg in membrane fraction of the kidney. Supplementation of potassium inhibited the effect of aldosterone on the Rhcg. Next, mice were subjected to adrenalectomy with or without administration of aldosterone, and then ad libitum 0.14 M NH4Cl containing water was given. NH4Cl load increased the expression of Rhcg in membrane fraction. Adrenalectomy decreased NH4Cl-induced Rhcg expression, which was restored by administration of aldosterone. Immunohistochemical studies revealed that NH4Cl load induced the localization of Rhcg at the apical membrane of ICs in the outer medullary collecting duct. Adrenalectomy decreased NH4Cl-induced membrane localization of Rhcg, which was restored by administration of aldosterone. For in vitro experiments, IN-IC cells, an immortalized cell line stably expressing Flag-tagged Rhcg (Rhcg-Flag), were used. Western blot analysis showed that aldosterone increased the expression of Rhcg-Flag in membrane fraction, while the increase in extracellular potassium level inhibited the effect of aldosterone. Both spironolactone and GÓ§6983, a PKC inhibitor, inhibited the expression of Rhcg-Flag in the membrane fraction. These results suggest that aldosterone regulates the membrane expression of Rhcg through the mineralocorticoid receptor and PKC pathways, which is modulated by extracellular potassium level.