Expression and function of renal and hepatic organic anion transporters in extrahepatic cholestasis

Obstructive jaundice occurs in patients suffering from cholelithiasis and from neoplasms affecting the pancreas and the common bile duct.The absorption,distribution and elimination of drugs are impaired during this pathology.Prolonged cholestasis may alter both liver and kidney function.Lactam antibiotics,diuretics,non-steroidal anti-inflammatory drugs,several antiviral drugs as well as endogenous compounds are classified as organic anions.The hepatic and renal organic anion transport pathways play a key role in the pharmacokinetics of these compounds.It has been demonstrated that acute extrahepatic cholestasis is associated with increased renal elimination of organic anions.The present work describes the molecular mechanisms involved in the regulation of the expression and function of the renal and hepatic organic anion transporters in extrahepatic cholestasis,such as multidrug resistanceassociated protein 2,organic anion transporting polypeptide 1,organic anion transporter 3,bilitranslocase,bromosulfophthalein/bilirubin binding protein,organic anion transporter 1 and sodium dependent bile salt transporter.The modulation in the expression of renal organic anion transporters constitutes a compensatory mechanism to overcome the hepatic dysfunction in the elimination of organic anions.

Effects of Cangfudaotan Tang on Expression of Organic Anion Transporting Polypeptide (oatp2b1) in Liver and Kidney Tissues of Rats with Phlegm Dampness Type Polycystic Ovary Syndrome (PCOS)

Objective: To explore the effect of Cangfudaotan Tang on phlegm dampness type of PCOS and the role of oatp2b1 in transportation and transformation of phlegm dampness. Methods: 36 SD female rats were randomly divided into three groups: blank control group, model group and Cangfudaotan Tang group, 12 cases in each one. After PCOS rat models were made, rats of Cangfudaotan Tang group were treated with Cangfudaotan Tang (1.42 g/kg/d) by intragastric administration for 14 days;blank control and model group were given with isodose saline. The expression of oatp2b1 mRNA/Protein in liver and kidney tissues was measured and the level of testosterone (T), follicle stimulating hormone(FSH), estradiol (E2), luteinizing hormone(LH), Serum total cholesterol (TG), Triacylglycerols (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were detected at the same time. Results: Compared with blank control group, the expression of oatp2b1 mRNA and the level of TC, TG, LDL, LH, FSH, T in model group were significantly increased (P < 0. 05), while the level of HDL was significantly decreased (P < 0. 05);compared with model group, the expression of oatp2b1 mRNA and the level of TC, TG, LDL in Cangfudaotan Tang group were significantly lowered (P < 0.05);the level of HDL was significantly higher;the oatp2b1 protein in kidney and liver tissues had different degrees of expression, while there was no statistical significance among the three groups. Conclusions: Oatp2b1 might be one of the material bases participating in transportation and transformation of phlegmy dampness. The mechanism of Cangfudaotan Tang treating phlegm dampness type of PCOS may be achieved by regulating the expression of oatp2b1.

Influence of organic anion transporting potypeptide(SLCO1B1 and SLCO1B3)genetic polymorphisms on mycophenolic acid in Chinese kidney transplantation patients

Objective To analyze the relationship between genetic polymorphisms of organic anion transporting polypeptide ( SLCO1B1 and SLCO1B3) and mycophenolic acid ( MPA) pharmacokinetics in Chinese kidney transplant recipients. Methods Gene mutations ( SLCO1B3 T334G,SLCO1B1 A338G) were detected in 68 recipi-

Overview of organic anion transporters and organic anion transporter polypeptides and their roles in the liver

Organic anion transporters(OATs)and organic anion transporter polypeptides(OATPs)are classified within two SLC superfamilies,namely,the SLC22A superfamily and the SLCO superfamily(formerly the SLC21A family),respectively.They are expressed in many tissues,such as the liver and kidney,and mediate the absorption and excretion of many endogenous and exogenous substances,including various drugs.Most are composed of 12 transmembrane polypeptide chains with the C-terminus and the N-terminus located in the cell cytoplasm.OATs and OATPs are abundantly expressed in the liver,where they mainly promote the uptake of various endogenous substrates such as bile acids and various exogenous drugs such as antifibrotic and anticancer drugs.However,differences in the locations of glycosylation sites,phosphorylation sites,and amino acids in the OAT and OATP structures lead to different substrates being transported to the liver,which ultimately results in their different roles in the liver.To date,few articles have addressed these aspects of OAT and OATP structures,and we study further the similarities and differences in their structures,tissue distribution,substrates,and roles in liver diseases.

Piperacillin enhances the inhibitory effect of tazobactam on β-lactamase through inhibition of organic anion transporter 1/3 in rats

To assess the mechanism of the pharmacokinetic interaction between piperacillin and tazobactam,renal excretion and pharmacokinetic studies of piperacillin/tazobactam were investigated in normal and bacteremia rats.A bacteremia model was established to investigate the pharmacokinetic properties of piperacillin and tazobactam under different conditions.Renal slices were taken to examine the uptake of piperacillin and tazobactam.Pharmacokinetic studies ofβ-lactamase in rats were performed to study the contribution of rOat1/3 to the inhibition of tazobactam onβ-lactamase.The AUC(from 2.93±0.58 to 6.52±1.44 mg·min/ml)and the plasma clearance(CL P)(from 2.41±1.20 to 0.961±0.212 ml/min/kg)of tazobactam were both altered after the intravenous coadministration of piperacillin and tazobactam in the bacteremia rats.The renal clearance(CL R)of tazobactam decreased from 1.30±0.50 to 0.361±0.043 ml/min/kg.In summary,there was a beneficial interaction between piperacillin and tazobactam mediated by rOat1 and rOat3.Piperacillin enhances the inhibitory effect of tazobactam onβ-lactamase through the inhibition of rOat1 and rOat3 in rats.The contribution rate of rOat1/3 for the synergistic effect was 20%when the two drugs were coadministered.

Curvature-regulated transmembrane anion transport by a trifluoromethylated bisbenzimidazole

In this paper,we demonstrate that modification of anion-transport:active l,3-bis(benzimidazol-2-yl)benzene with strongly electron-withdrawing trifluoromethyl and nitro groups leads to a dramatic increase in the anionophoric activity,and the activity may be greatly regulated by the curvatures of the liposomes used.

Insulin-like growth factor 1 modulates the phosphorylation, expression, and activity of organic anion transporter 3 through protein kinase A signaling pathway

Organic anion transporter 3(OAT3)plays a vital role in removing a broad variety of anionic drugs from kidney,thus avoiding their possible toxicity in the body.In the current study,we investigated the role of insulin-like growth factor 1(IGF-1)in the regulation of OAT3.We showed that IGF-1 induced a dose-and time-dependent increase in OAT3 transport activity,which correlated well with an increase in OAT3 expression.The IGF-1-induced increase in OAT3 expression was blocked by protein kinase A(PKA)inhibitor H89.Moreover,IGF-1 induced an increase in OAT3 phosphorylation,which was also blocked by H89.These data suggest that the IGF-1 modulation of OAT3 occurred through PKA signaling pathway.To further confirm the involvement of PKA,we treated OAT3-expressing cells with PKA activator Bt’2-cAMP,followed by examining OAT activity and phosphorylation.We showed that OAT3 activity and phosphorylation were much enhanced in Bt2-cAMP-treated cells as compared to that in control cells.Finally,linsitinib,an anticancer drug that blocks the IGF-1 receptor,abrogated IGF-1-stimulated OAT3 transport activity.In conclusion,our study demonstrated that IGF-1 regulates OAT3 expression and transport activity through PKA signaling pathway,possibly by phosphorylating the transporter.

Ionic covalent organic frameworks with tailored anionic redox chemistry and selective ion transport for high-performance Na-ion cathodes

Employing cathode materials with multiple redox couples and electrolytes with efficient cation transport kinetics are two effective approaches to improving the electrochemical performance of batteries.In this work,for the first time,we present a design strategy of simultaneously realizing reversible cationic and anionic redox chemistries as well as selective anion/cation transport in the viologen-based COFs(BAVCOF:X,coordinated anions of X=Cl^(-),Br^(-),I^(-),and ClO_(4)^(-))for high-performance Na-ion cathodes.Besides the cationic redox of viologen segments,the different redox activities of anions effectively tune the total capacities of the COFs.Meanwhile,electrochemical analysis and ab-initial molecular dynamics(AIMD)calculation illustrate that the anion/cation transport kinetics of electrolytes caged in the COFs'channels can be selectively tuned by the coordinated anions.As a result,combining high-potential Br-/Br_(2)redox couple,cationic redox of viologen segments,and enhanced Na+transport kinetics,the BAV-COF:Brdemonstrates stable performance with energy densities of 358.7 and 145.2 Wh kg^(-1)at power densities of 116.5 and 2124.1 W kg^(-1),respectively.This study offers new insight into the fabrication of organic cathodes with anionic redox and the advantages of COFs electrode materials in anion/cation transport selectivity for energy storage applications.

Gadoxetic acid-enhanced magnetic resonance imaging in the assessment of hepatic sinusoidal obstruction syndrome in a mouse model

BACKGROUND Neoadjuvant chemotherapy can cause hepatic sinusoidal obstruction syndrome(SOS)in patients with colorectal cancer liver metastases and increases posto-perative morbidity and mortality.AIM To evaluate T1 mapping based on gadoxetic acid-enhanced magnetic resonance imaging(MRI)for diagnosis of hepatic SOS induced by monocrotaline.METHODS Twenty-four mice were divided into control(n=10)and experimental(n=14)groups.The experimental groups were injected with monocrotaline 2 or 6 days before MRI.MRI parameters were:T1 relaxation time before enhancement;T1 relaxation time 20 minutes after enhancement(T_(1post));a reduction in T1 relaxation time(△T_(1)%);and first enhancement slope percentage of the liver parenchyma(ESP).Albumin and bilirubin score was determined.Histological results served as a reference.Liver parenchyma samples from the control and experimental groups were analyzed by western blotting,and organic anion transporter polypeptide 1(OATP1)was measured.RESULTS T_(1post),△T_(1)%,and ESP of the liver parenchyma were significantly different between two groups(all P<0.001)and significantly correlated with the total histological score of hepatic SOS(r=-0.70,0.68 and 0.79;P<0.001).△T_(1)%and ESP were positively correlated with OATP1 levels(r=0.82,0.85;P<0.001),whereas T_(1post) had a negative correlation with OATP1 levels(r=-0.83;P<0.001).INTRODUCTION Hepatic sinusoidal obstruction syndrome(SOS)is also known as hepatic veno-occlusive disease of the liver[1].The main pathological feature of hepatic SOS is damage to liver terminal vessels,and the clinical symptoms of it include ascites and abdominal pain[2].It was first proposed in 1979 as an early complication of hematopoietic stem cell transplantation[3].The prevalence ranges from 5%to 60%,and hepatic SOS is a potentially severe complication and can even lead to death in severe cases[4].Recently,systemic neoadjuvant chemotherapy became widely regarded as one of the causes hepatic SOS in the patients with advanced metastatic colorectal cancer[5,6],especially those were treated with oxaliplatin[7,8].Oxaliplatin-based preoperative chemotherapy is used for patients with colorectal liver metastases as the standard regimen[8,9],because it could improve tumor resection outcome by shrinking the metastatic sites and reducing recurrence rate[10].Nevertheless,chemotherapy-induced hepatic SOS has been associated with a higher risk of postresection morbidity[11],such as intraoperative bleeding,intraoperative transfusions,and postoperative liver failure[12].Therefore,it is important to detect and diagnose of hepatic SOS timely.Currently,the gold standard is still based on liver biopsy[13],but it is an invasive procedure and has several limitations and complications,such as hemorrhage[14].A noninvasive diagnostic modality is needed for the assessment of hepatic SOS.Some noninvasive tools have been used for diagnosis of hepatic SOS.Researchers have utilized a preoperative platelet count and aspartate aminotransferase to platelet ratio index[15].In addition,some imaging methods such as shear wave ultrasonography,computed tomography,and gadoxetic acid-enhanced magnetic resonance imaging(MRI)have been promoted as useful methods for evaluation of hepatic SOS[16-18].Recent studies with monocrotaline(MCT)-treated rats were conducted to investigate diagnosis and prediction of severity of SOS.For example,intravoxel incoherent motion diffusion-weighted imaging,non-Gaussian diffusion models,and T1 rho quantification[19,20].The MCT-induced hepatic SOS animal model was reproducible,with a detailed pathological scoring criteria[21].Gadoxetic acid is a hepatocyte-specific contrast substance,which can provide parenchymal contrast in the hepato-biliary phase.It is reported that gadoxetic acid is absorbed into the liver parenchyma via organic anion transporter polypeptide 1(OATP1)on the hepatocyte membranes[22-24].Recently,several authors have described the feasibility of gadoxetic acid-enhanced MRI for the diagnosis of oxaliplatin-induced hepatic SOS[25].They mainly diagnosed hepatic SOS based on the signal intensity of the hepatobiliary specific phase.However,there were several limitations due to the inconsistency between signal intensity of the liver parenchyma and the concentration of contrast agent for evaluation of the degree of hepatic SOS[26].Therefore,we measured T1 relaxation time on parametric mapping because it is linearly related to the concentration of the contrast agent and is not affected by other factors[27].Yang et al[28]demonstrated T1 mapping on gadoxetic acid-enhanced MRI for the assessment of oxaliplatin-induced liver injury in a C57BL/6 mouse model.However,the main pathological changes in their model were hepatocyte degeneration and fibrosis.Therefore,we aimed to explore the effectiveness of T1 mapping based on gadoxetic acid-enhanced MRI for the diagnosis of hepatic SOS in a C57BL/6 mouse model,as well as a possible relation between OATP1 Levels and MRI parameters.

PGE_(2)通过EP4/PKA信号通路调控滑膜细胞OAT1的表达及CP-25的作用

目的明确前列腺素E2(prostaglandin E2,PGE_(2))对滑膜细胞有机阴离子转运体1(organic anion transporter 1,OAT1)膜表达的调控机制及芍药苷-6'-O-苯磺酸酯(CP-25)的作用。方法免疫荧光法检测不同浓度CP-25对PGE_(2)处理后滑膜细胞OAT1和前列腺素E受体4(prostaglandin E receptor 4,EP4)表达的影响;使用EP4激动剂(TCS2510)与拮抗剂(GW627368X),探究EP4在OAT1调节中的作用;使用CP-25和蛋白激酶A(protein kinase A,PKA)抑制剂H-89,探究CP-25和PKA对滑膜细胞OAT1表达的影响。结果PGE_(2)在0~10 min内明显下调EP4与OAT1的膜表达,20~60 min后明显上调(P<0.05);CP-25明显上调PGE_(2)处理后细胞膜OAT1和EP4的表达(P<0.05);EP4激动剂TCS2510明显上调细胞膜OAT1的表达(P<0.01);CP-25上调PGE_(2)处理的细胞中OAT1的表达,GW627368X和H-89均能下调PGE_(2)和CP-25处理的滑膜细胞中OAT1的表达(P<0.01)。结论PGE_(2)介导的EP4/PKA信号通路可以调控OAT1在滑膜细胞膜上的表达,CP-25可以通过活化EP4/PKA信号通路明显上调滑膜细胞中OAT1的膜表达。

GABA transporter 1 transcriptional starting site exhibiting tissue specific difference

GABA transporter 1(GAT1) takes important roles in multiple physiological processes through the uptake and release of GABA, but the regulation of GAT1 gene expression in different tissues is rarely known. To address the question, first, 5’ Rapid amplification of cDNA end (RACE) was used to determine GAT1 transcriptional starting sites in neonatal mouse cerebral cortex and intestine, adult mouse brain and adult rat testis. The products of 5’RACE were confirmed by DNA sequencing. We found that the transcript of GAT1 in neonatal mouse cerebral cortex and adult mouse brain starts at the same site (inside of exon 1), while in mouse intestine, GAT1 starts transcription in intron 1, and in rat testis, the transcript of GAT1 has an additional untranslation exon to the 5’ direction.

Hepatocellular transport proteins and their role in liver disease

MOLECULAR PHYSIOLLGY OF HEPATOCELLULAR TRANSPORT PROTEINS Basolaferal transport systems Na+-dependent bile salt uptake Uptake of bile salts into the liver was first isolated perfused rat liver[1],isolated hepatocyte cultures and basolateral plasma membrane vesicles [2,4].

Differential expression of cholangiocyte and ileal bile acid transporters following bile acid supplementation and depletion

AIM: We have previously demonstrated that cholangiocytes, the epithelial cells lining intrahepatic bile ducts,encode two functional bile acid transporters via alternative splicing of a single gene to facilitate bile acid vectorial transport. Cholangiocytes possess ASBT,an apical sodium-dependent bile acid transporter to take up bile acids,and t-ASBT,a basolateral alternatively spliced and truncated form of ASBT to efflux bile acids.Though hepatocyte and ileal bile acid transporters are in part regulated by the flux of bile acids, the effect of alterations in bile acid flux on the expression of t-ASBT in terminal ileocytes remains undear.Thus,we tested the hypothesis that expression of ASBT and t-ASBT in cholangiocytes and ileocytes was regulated by bile acid flux. METHODS: Expression of ASBT and t-ASBT message and protein in cholangiocytes and ileocytes isolated from pair- fed rats given control (C) and 1% taurocholate (TCA) or 5% cholestyramine (CY) enriched diets,were assessed by both quantitative RNase protection assays and quantitative immunoblotting.The data obtained from each of the control groups were pooled to reflect the changes observed following TCA and CY treatments with respect to the control diets. Cholangiocyte taurocholate uptake was determined using a novel microperfusion technique on intrahepatic bile duct units (IBDUs) derived from C,TCA and CY fed rats. RESULTS: In cholangiocytes,both ASBT and t-ASBT message RNA and protein were significantly decreased in response to TCA feeding compared to C diet.In contrast, message and protein of both bile acid transporters significantly increased following CY feeding compared to C diet.In the ileum,TCA feeding significantly up-regulated both ASBT and t-ASBT message and protein compared to C diet,while CY feeding significantly down-regulated message and protein of both bile acid transporters compared to C diet.As anticipated from alterations in cholangiocyte ASBT expression,the uptake of taurocholate in microperfused IBDUs derived from rats on TCA diet decreased 2.7-fold,whereas it increased 1.7-fold in those on CY diet compared to C diet fed groups. CONCLUSION: These data demonstrate that expression of ASBT and t-ASBT in cholangiocytes is regulated by a negative feedback loop while the expression of these transporters in terminal ileum is modified via positive feedback.Thus, while transcriptional regulatory mechanisms in response to alterations in bile acid pool size are operative in both cholangiocytes and ileocytes,each cell type responds differently to bile acid supplementation and depletion.

慢性肾衰竭大鼠OAT1的表达对骨代谢的影响

目的研究慢性肾衰竭时导致骨细胞有机阴离子转运蛋白(organic anion transporter,OAT)表达的变化,探讨OAT1表达对骨代谢的影响。方法将SD大鼠随机分为对照组(Control,n=6)和模型组(Model,n=6)。模型组采用“单肾切除+腺嘌呤灌胃法”建立大鼠慢性肾衰竭模型,通过血常规分析仪测定大鼠血清的红细胞(red blood cell,RBC)、血红蛋白(hemoglobin,Hb);通过全自动生化分析仪测定肌酐(creatinine,Cr)、尿素氮(urea nitrogen,BUN)、尿酸(uric acid,UA)、血钙(Ca^(2+))、血磷(P^(3+))等指标;对大鼠肾脏进行病理学检查;X线拍片检查大鼠胫骨标本;免疫组化检查骨组织OAT1表达。结果模型组大鼠的骨密度低于对照组;模型组大鼠钙磷代谢失调,并且骨组织结合OAT1值远低于对照组,差异具有统计学意义(P=0.0018)。结论慢性肾功衰竭影响OAT1在骨组织中的表达,导致钙磷代谢失调,从而加重肾性骨营养不良。

SLCO1B1和ApoE基因多态性与冠心病关系的研究

目的探讨溶质载体有机阴离子转运蛋白家族1B1(SLCO1B1)和载脂蛋白E(ApoE)基因多态性与冠状动脉粥样硬化性心脏病(冠心病)的关系。方法选取2020年1月至2022年6月于甘肃省武威肿瘤医院心血管内科收治的80例冠心病患者作为观察组,同一时间选取本院体检的80例健康者作为对照组,抽取外周血检测SLCO1B1和ApoE基因多态性,全自动生化分析仪检测血脂指标,Logistic分析冠心病的危险因素。结果对照组与观察组SLCO1B1基因型15/15、1a/15、1a/1a、1a/1b、1a/5、1b/15及1b/1b、等位基因15、1a、1b及5比较,差异无统计学意义(P>0.05)。观察组ApoE等位基因ε2及ε3的占比显著高于对照组(P<0.05)。与对照组相比,观察组患者SLCO1B1基因在1b/15型上总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)及载脂蛋白B(ApoB)水平升高,1a/15型TG水平升高,1a/1b型上高密度脂蛋白胆固醇(HDL-C)及载脂蛋白A1(ApoA1)降低,1b/1b型上TG升高,HDL-C及ApoA1降低(P<0.05)。与对照组相比,观察组ApoE基因在E2/E3型HDL-C降低,E3/E3型TG升高,HDL-C及ApoA1水平降低,E3/E4型HDL-C及ApoA1水平降低(P<0.05)。以冠心病为因变量,以上述结果中P<0.05的因素(高血压、糖尿病、TG、LDL-C、ApoA1、ApoB、ε3及ε4)作为自变量,运用Logistic回归分析结果发现,高血压、糖尿病、TG、LDL-C、ApoA1、ApoB及ApoE基因ε4型是诱发冠心病的危险因素(P<0.05)。结论SLCO1B1和ApoE基因多态性与血脂水平异常相关,ApoE基因ε4型可提高冠心病的发生。

台儿庄地区心脑血管疾病患者ApoE和SLCO1B1基因多态性分析

目的:分析台儿庄地区心脑血管疾病患者他汀类药物代谢相关基因ApoE和SLCO1B1的基因多态性分布情况,评估患者对服用他汀类药物的疗效和风险,指导临床进行个体化精准用药。方法:以2022年3月-2023年1月与台儿庄人民医院神经内科及心内科就诊的268例心脑血管病患者为研究对象,应用DNA连接酶测序法对患者外周血基因组中ApoE和SLCO1B1基因进行检测,分析基因多态性分布情况,并比较不同性别,不同年龄段,不同地域间的基因型分布差异。结果:观察268例台儿庄地区心脑血管病患者的ApoE及SLCO1B1基因位点多态性突变频率符合Hardy-Weinberg遗传平衡定律。ApoE基因型共检出5种,其中E3/E3型占比最大,为76.9%,其他基因型E2/E2型,E2/E3型,E3/E4型,E4/E4型占比依次为0.37%,10.4%,11.9%,0.37%,未检出E2/E4型。疗效正常基因型E3型(E2/E4+E3/E3)占比最高,为76.87%,疗效较好基因型E2型(E2/E2+E2/E3)与疗效较差基因型E4型(E3/E4+E4/E4)占比分别为10.82%,12.31%。不同性别,不同年龄患者间ApoE不同疗效基因型分布差异无统计学意义(P>0.05),但不同地区间比较,ApoE不同疗效基因型分布差异有统计学意义(P<0.05)。SLCO1B1基因共检出6种基因型,其中*1b/*1b,*1b/*15,*1a/*1b占比较高,分别为28.73%,20.15%,41.79%,其他基因型*1a/*1a,*1a/*15or*1b/*5,*15/*15频率分别为5.6%,3.36%,0.37%,未检测到*1a/*5、*5/*5和*5/*15基因型。基因型组合中,肌病低风险基因型(*1a/*1a+*1a/*1b+*1b/*1b)占比最高为76.12%,肌病中风险基因型(*1a/*5+*1a/*15or*1b/*5+*1b/*15)和肌病高风险基因型(*5/*5+*5/*15+*15/*15)占比分别为23.51%,0.37%。不同性别,不同年龄,不同地区间患者比较,SLCO1B1不同肌病风险基因型频率分布差异均无统计学意义(P>0.05)。结论:台儿庄地区心脑血管病患者ApoE基因以疗效正常型E3型为主,SLCO1B1基因以肌病低风险基因型为主,且两种基因型各组合与年龄,性别无关,ApoE基因存在地区差异。通过基因检测可筛选出12.31%疗效较差的患者以及23.88%的肌病中高风险患者,可辅助临床制定合理的用药方案。

Evaluating the regulation of transporter proteins and P-glycoprotein in rats with cholestasis and its implication for digoxin clearance

BACKGROUND Cardiac and hepatic functionality are intertwined in a multifaceted relationship.Pathologic processes involving one may affect the other through a variety of mechanisms,including hemodynamic and membrane transport effects.AIM To better understand the effect of extrahepatic cholestasis on regulations of membrane transporters involving digoxin and its implication for digoxin clearance.METHODS Twelve adult rats were included in this study;baseline hepatic and renal laboratory values and digoxin pharmacokinetic(PK)studies were established before evenly dividing them into two groups to undergo bile duct ligation(BDL)or a sham procedure.After 7 d repeat digoxin PK studies were completed and tissue samples were taken to determine the expressions of cell membrane transport proteins by quantitative western blot and real-time polymerase chain reaction.Data were analyzed using SigmaStat 3.5.Means between pre-surgery and post-surgery in the same experimental group were compared by paired t-test,while independent t-test was employed to compare the means between sham and BDL groups.RESULTS Digoxin clearance was decreased and liver function,but not renal function,was impaired in BDL rats.BDL resulted in significant up-regulation of multidrug resistance 1 expression in the liver and kidney and its down-regulation in the small intestine.Organic anion transporting polypeptides(OATP)1A4 was up-regulated in the liver but down-regulated in intestine after BDL.OATP4C1 expression was markedly increased in the kidney following BDL.CONCLUSION The results suggest that cell membrane transporters of digoxin are regulated during extrahepatic cholestasis.These regulations are favorable for increasing digoxin excretion in the kidney and decreasing its absorption from the intestine to compensate for reduced digoxin clearance due to cholestasis.

Expression of renal Oat5 and NaDC1 transporters in rats with acute biliary obstruction

AIM: To examine renal expression of organic anion transporter 5(Oat5) and sodium-dicarboxylate cotransporter 1(Na DC1), and excretion of citrate in rats with acute extrahepatic cholestasis.METHODS: Obstructive jaundice was induced in rats by double ligation and division of the common bile duct(BDL group). Controls underwent sham operation that consisted of exposure, but not ligation, of the common bile duct(Sham group). Studies were performed 21 h after surgery. During this period, animals were maintained in metabolic cages in order to collect urine. The urinary volume was determined by gravimetry. The day of the experiment, blood samples were withdrawn and used to measure total and direct bilirubin as indicative parameters of hepatic function. Serum and urine samples were used for biochemical determinations. Immunoblotting for Oat5 and Na DC1 were performed in renal homogenates and brush border membranes from Sham and BDL rats. Immunohistochemistry studies were performed in kidneys from both experimental groups. Total RNA was extracted from rat renal tissue in order to perform reverse transcription polymerase chain reaction. Another set of experimental animals were used toevaluate medullar renal blood flow(m RBF) using fluorescent microspheres.RESULTS: Total and direct bilirubin levels were significantly higher in BDL animals, attesting to the adequacy of biliary obstruction. An important increase in m RBF was determined in BDL group(Sham: 0.53 ± 0.12 m L/min per 100 g body weight vs BDL: 1.58 ± 0.24 m L/min per 100 g body weight, P < 0.05). An increase in the urinary volume was observed in BDL animals. An important decrease in urinary levels of citrate was seen in BDL group. Besides, a decrease in urinary citrate excretion(Sham: 0.53 ± 0.11 g/g creatinine vs BDL: 0.07 ± 0.02 g/g creatinine, P < 0.05) and an increase in urinary excretion of H+(Sham: 0.082 ± 0.03 μmol/g creatinine vs BDL: 0.21 ± 0.04 μmol/g creatinine, P < 0.05) were observed in BDL animals. We found upregulations of both proteins Oat5 and Na DC1 in brush border membranes where they are functional. Immunohistochemistry technique corroborated these results for both proteins. No modifications were observed in Oat5 m RNA and in Na DC1 m RNA levels in kidney from BDL group as compared with Sham ones.CONCLUSION: Citrate excretion is decreased in BDL rats, at least in part, because of the higher Na DC1 expression. Using the outward gradient of citrate generated by Na DC1, Oat5 can reabsorb/eliminate different organic anions of pathophysiological importance.

代谢相关脂肪性肝病患者SLCO1B1和APOE基因多态性与脂代谢紊乱关系研究

目的 分析代谢相关脂肪性肝病(MAFLD)患者有机阴离子转运蛋白1B1(SLCO1B1)和载脂蛋白E(APOE)基因多态性与脂代谢紊乱的关系。方法 2018年8月~2021年8月我院诊治的MAFLD患者121例和同期健康体检者150例,常规检测血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)水平,采用PCR-荧光探针法检测外周血SLCO1B1和APOE基因型。结果 MAFLD组血清TC、TG和LDL-C水平分别为(5.8±2.3)mmol/L、(2.9±1.4)mmol/L和(3.3±1.5)mmol/L,均显著高于健康人【分别为(4.8±1.2)mmol/L、(1.5±1.3)mmol/L和(2.6±1.1)mmol/L,P<0.05】;MAFLD组SLCO1B1基因*1a/*1a和*1a/*1b基因型频率分别为8.3%和35.5%,显著高于健康人的2.7%和23.3%(P<0.05),而*1b/*1b基因型频率为32.2%,显著低于健康人的46.0%(P<0.05);MAFLD组APOE基因ε3/3基因型频率和E3基因表型频率分别为69.4%和71.9%,显著高于健康人的56.7%和58.7%(P<0.05),而ε3/4基因型频率和E4基因表型频率分别为17.4%和18.2%,均显著低于健康人的29.3%和30.7%(P<0.05);26例SLCO1B1基因B型患者血清TC、TG和LDL-C水平分别为(6.4±1.2)mmol/L、(3.5±2.2)mmol/L和(3.8±0.8)mmol/L,均显著高于92例A型患者【分别为(5.5±1.3)mmol/L、(2.6±3.3)mmol/L和(3.0±1.2)mmol/L,P<0.05】或3例C型患者【分别为(4.6±0.3)mmol/L、(2.6±0.9)mmol/L和(2.5±0.2)mmol/L,P<0.05】;87例APOE基因E3型血清TG和LDL-C水平分别为(3.2±1.6)mmol/L和(3.4±1.1)mmol/L,显著高于12例E2型【分别为(2.7±1.8)mmol/L和(2.8±0.8)mmol/L,P<0.05】或22例E4型【分别为(2.3±0.7)mmol/L和(3.0±1.2)mmol/L,P<0.05】。结论 MAFLD患者SLCO1B1和APOE基因多态性与脂代谢紊乱密切相关,值得深入研究。

硫酸吲哚酚诱导5/6肾切除慢性肾脏病大鼠心肌肥大及纤维化的作用机制研究

目的探讨硫酸吲哚酚(IS)对5/6肾切除慢性肾脏病(CKD)大鼠模型心肌肥大及纤维化的作用。方法20只SD大鼠按随机数字表法分为正常组和5/6肾切除CKD大鼠组(模型组),每组10只。模型组建立5/6肾切除CKD模型。比较2组大鼠体质量、心脏及左心室质量;观察造模前后2组血液中血肌酐、尿素及IS水平;分析2组大鼠心脏组织中有机阴离子转运蛋白-3(OAT-3)、氧化应激烟酰胺腺嘌呤二核苷酸磷酸氧化酶-4(Nox-4)、抗氧化蛋白[核因子-E2相关因子-2(Nrf-2)、下游基因血红素加氧酶-1(HO-1)]、心肌肥大指标[心房利钠肽(ANP)、脑钠肽(BNP)、β-肌球蛋白重链(β-MHC)]及纤维化指标[转化生长因子-β1(TGF-β1)、Smad-3、Ⅰ型胶原蛋白(CollagenⅠ)mRNA]表达水平。结果与正常组比较,模型组体质量降低,心脏和左心室质量显著增加(P<0.05,P<0.01)。模型组大鼠造模12周后血肌酐、尿素及IS水平高于造模前和正常组(P<0.05,P<0.01)。与正常组比较,模型组大鼠心脏组织中OAT-3、Nox-4、ANP、BNP、β-MHC、TGF-β1、Smad-3及CollagenⅠmRNA表达水平升高,Nrf-2、HO-1 mRNA表达水平降低(P<0.01)。结论在5/6肾切除CKD大鼠中IS经OAT-3摄取,进而激活氧化应激反应,最终引起心肌肥大及纤维化。