Acetaminophen is a drug used to treat many conditions as headache, muscle aches, arthritis, backache, toothache, and fever between others, but collateral effects of this drug are not well known yet. Here is tested its...Acetaminophen is a drug used to treat many conditions as headache, muscle aches, arthritis, backache, toothache, and fever between others, but collateral effects of this drug are not well known yet. Here is tested its effect on proximal tubule epithelium. Acetaminophen (APAP) at doses of 200, 500, 1000 and 1500 mg/Kg i.p. caused cell damage and changes in F-actin distribution in the proximal tubule of male Wistar rats. After 48 hours of treatment, the proximal tubule epithelium showed tumefaction and necrosis. Dose of 200 mg/kg decreased the F-actin and was observed a structure in patches in the basal cytoplasm of epithelial cells of the proximal tubule. This effect was increased depending on the administered dose. Dose of 1000 mg/kg produced the highest histological damage and changes in the actin cytoskeleton. Results of this study suggested that nephrotoxic damage produced by high doses of APAP included breakdown of cytoskeleton in proximal tubule epithelium.展开更多
Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote r...Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote renal tubule regeneration in AKI through the regulation of the PTEN signaling pathway by miR-21.BMSCs were isolated and characterized,and their exosomes were purified.In vitro,renal tubular epithelial cell injury models were established,and the co-culture of exosomes and cells demonstrated enhanced cell proliferation and reduced apoptosis.In vivo,AKI animal models showed improved renal function and histopathological changes after exosome treatment.miR-21 was found to be upregulated in exosomes and recipient cells,targeting PTEN and activating the PI3K/AKT pathway.The signaling network also interacted with other pathways related to renal tubule regeneration.The study highlights the potential of exosome therapy for AKI and provides insights into the underlying molecular mechanisms,although further research is needed to address remaining challenges and translate these findings into clinical applications.展开更多
Kidney disease is an escalating global health problem,for which the formulation of therapeutic approaches using stem cells has received increasing research attention.The complexity of kidney anatomy and function,which...Kidney disease is an escalating global health problem,for which the formulation of therapeutic approaches using stem cells has received increasing research attention.The complexity of kidney anatomy and function,which includes the diversity of renal cell types,poses formidable challenges in the identification of methods to generate replacement structures.Recent work using the zebrafish has revealed their high capacity to regenerate the integral working units of the kidney,known as nephrons,following acute injury.Here,we discuss these findings and explore the ways that zebrafish can be further utilized to gain a deeper molecular appreciation of renal stem cell biology,which may uncover important clues for regenerative medicine.展开更多
Acute tubular necrosis(ATN)induced by ischemia is the most common insult to donor kidneysdestined for trarsplantation.ATN results from sweling and subsequent damage to cells lining thelkidney tubules.In this study,we ...Acute tubular necrosis(ATN)induced by ischemia is the most common insult to donor kidneysdestined for trarsplantation.ATN results from sweling and subsequent damage to cells lining thelkidney tubules.In this study,we demonstrate the capability of optical coherence tomography(OcT)to image the renal microst ructures of living human donor kidneys and potentially providea measure to det ermine the extent of A TN.We also found that Doppler-based OCT(i.e.,DOCT)reveals renal blood flow dynamics that is another major factor which could relate to post-transplant renal finction.All OCT/DoCT oberva tions were performed in a noninvasive,sterileand timely manner on intact human kidneys both prior to(er vivo)and following(in vivo)theirtransplantation.Our results indicate that this imaging model provides transplant surgeons withan objective visualization of the transplant lidneys prior and immediately post transplantation.展开更多
Current dialysis systems are not perfect considering the low efficacy and cumbersome process of actual practice. To overcome these shortcomings, bioartificial kidneys using renal tubule cells and wearable dialysis are...Current dialysis systems are not perfect considering the low efficacy and cumbersome process of actual practice. To overcome these shortcomings, bioartificial kidneys using renal tubule cells and wearable dialysis are promising ESRD treatments available in the near future. Toward clinical application, however, there are so many obstacles for commercial use of them. In this review, current status of bioartificial kidneys such as the renal tubule cell assist device (RAD) and wearable dialysis devices is presented with the comparison to show the advantages and disadvantages.展开更多
950350 Improving lithium clearance——a methodfor measuring sodium delivery of tubule in human.WANG Huamin(王化民),et al.Nephrol Div,1stTeach Hosp,Beijing Med Univ.Chin J Nephrol 1994;10(6):326-328.Based on the method...950350 Improving lithium clearance——a methodfor measuring sodium delivery of tubule in human.WANG Huamin(王化民),et al.Nephrol Div,1stTeach Hosp,Beijing Med Univ.Chin J Nephrol 1994;10(6):326-328.Based on the method for lithium clearance,we ob-served the relationship between serum lithium concen-tration at the fouth hour in the test and the representa-tive serum lithium concentration,and verified that展开更多
The mechanism of how SARS-CoV-2 causes severe multi-organ failure is largely unknown. Acute kidney injury(AKI) is one of the frequent organ damage in severe COVID-19 patients. Previous studies have shown that human re...The mechanism of how SARS-CoV-2 causes severe multi-organ failure is largely unknown. Acute kidney injury(AKI) is one of the frequent organ damage in severe COVID-19 patients. Previous studies have shown that human renal tubule cells could be the potential host cells targeted by SARS-CoV-2. Traditional cancer cell lines or immortalized cell lines are genetically and phenotypically different from host cells. Animal models are widely used, but often fail to reflect a physiological and pathogenic status because of species tropisms. There is an unmet need for normal human epithelial cells for disease modeling. In this study, we successfully established long term cultures of normal human kidney proximal tubule epithelial cells(KPTECs) in 2 D and 3 D culture systems using conditional reprogramming(CR) and organoids techniques.These cells had the ability to differentiate and repair DNA damage, and showed no transforming property. Importantly, the CR KPTECs maintained lineage function with expression of specific transporters(SLC34 A3 and cubilin). They also expressed angiotensin-converting enzyme 2(ACE2), a receptor for SARS-CoV and SARS-CoV-2. In contrast, cancer cell line did not express endogenous SLC34 A3, cubilin and ACE2. Very interestingly, ACE2 expression was around twofold higher in 3 D organoids culture compared to that in 2 D CR culture condition. Pseudovirion assays demonstrated that SARS-CoV spike(S) protein was able to enter CR cells with luciferase reporter. This integrated 2 D CR and 3 D organoid cultures provide a physiological ex vivo model to study kidney functions, innate immune response of kidney cells to viruses, and a novel platform for drug discovery and safety evaluation.展开更多
970375 Amino acid metabolism analysis and protec-tion against injury to isolated proximal tubules incu-bated with cyclosporin A. JIANG Tang(姜傥), etal. Kidney Instit, 1st Affili Hosp, Sun Yat-sen Med U-niv, Guangzhou...970375 Amino acid metabolism analysis and protec-tion against injury to isolated proximal tubules incu-bated with cyclosporin A. JIANG Tang(姜傥), etal. Kidney Instit, 1st Affili Hosp, Sun Yat-sen Med U-niv, Guangzhou, 510080. Chin J Nephrol 1996; 12(6):347-351. Objective: To study the mechanism of cyclosporin展开更多
OBJECTIVE: To investigate the effect of L-arginine (L-arg) on early compensatory renal growth (CRG), tubulointerstitial accumulation of extracellular matrix (ECM), long term survival rate and renal scarring in rats wi...OBJECTIVE: To investigate the effect of L-arginine (L-arg) on early compensatory renal growth (CRG), tubulointerstitial accumulation of extracellular matrix (ECM), long term survival rate and renal scarring in rats with 5/6 nephrectomy (SNx). METHODS: The experiment included four groups of rats (n = 5 each group): (1) Sham group, (2) SNx group, (3) SNx + L-arg group, and (4) Sham + L-arg group (L-arg 1% in drinking water). Parameters related with CRG and early tubulointerstitial expression of ECM and alpha smooth muscle actin (alphaSMA) were evaluated by immunohistochemistry at day 30. The survival rate and the extent of renal scarring in the rats were observed at day 120. RESULTS: L-arg significantly increased the early CRG of SNx rats as determined by the wet kidney weight (P展开更多
Background:Ischemic acute kidney injury(AKI)is a common syndrome associated with considerable mortality and healthcare costs.Up to now,the underlying pathogenesis of ischemic AKI remains incompletely understood,and sp...Background:Ischemic acute kidney injury(AKI)is a common syndrome associated with considerable mortality and healthcare costs.Up to now,the underlying pathogenesis of ischemic AKI remains incompletely understood,and specific strategies for early diagnosis and treatment of ischemic AKI are still lacking.Here,this study aimed to define the transcriptomic landscape of AKI patients through single-cell RNA sequencing(scRNA-seq)analysis in kidneys.Methods:In this study,scRNA-seq technology was applied to kidneys from two ischemic AKI patients,and three human public scRNA-seq datasets were collected as controls.Differentially expressed genes(DEGs)and cell clusters of kidneys were determined.Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis,as well as the ligand-receptor interaction between cells,were performed.We also validated several DEGs expression in kidneys from human ischemic AKI and ischemia/reperfusion(I/R)injury induced AKI mice through immunohistochemistry staining.Results:15 distinct cell clusters were determined in kidney from subjects of ischemic AKI and control.The injured proximal tubules(PT)displayed a proapoptotic and proinflammatory phenotype.PT cells of ischemic AKI had up-regulation of novel pro-apoptotic genes including USP47,RASSF4,EBAG9,IER3,SASH1,SEPTIN7,and NUB1,which have not been reported in ischemic AKI previously.Several hub genes were validated in kidneys from human AKI and renal I/R injury mice,respectively.Furthermore,PT highly expressed DEGs enriched in endoplasmic reticulum stress,autophagy,and retinoic acid-inducible gene I(RIG-I)signaling.DEGs overexpressed in other tubular cells were primarily enriched in nucleotide-binding and oligomerization domain(NOD)-like receptor signaling,estrogen signaling,interleukin(IL)-12 signaling,and IL-17 signaling.Overexpressed genes in kidney-resident immune cells including macrophages,natural killer T(NKT)cells,monocytes,and dendritic cells were associated with leukocyte activation,chemotaxis,cell adhesion,and complement activation.In addition,the ligand-receptor interactions analysis revealed prominent communications between macrophages and monocytes with other cells in the process of ischemic AKI.Conclusion:Together,this study reveals distinct cell-specific transcriptomic atlas of kidney in ischemic AKI patients,altered signaling pathways,and potential cell-cell crosstalk in the development of AKI.These data reveal new insights into the pathogenesis and potential therapeutic strategies in ischemic AKI.展开更多
Objective:Dopamine,via its receptors,plays a vital role in the maintenance of blood pressure by modulating renal sodium transport.However,the role of the D_(4)dopamine receptor(D_(4)receptor)in renal proximal tubules(...Objective:Dopamine,via its receptors,plays a vital role in the maintenance of blood pressure by modulating renal sodium transport.However,the role of the D_(4)dopamine receptor(D_(4)receptor)in renal proximal tubules(PRTs)is still unclear.This study aimed to verify the hypothesis that activation of D_(4)receptor directly inhibits the activity of the Na+-K+-ATPase(NKA)in RPT cells.Methods:NKA activity,nitric oxide(NO)and cyclic guanosine monophosphate(cGMP)levels were measured in RPT cells treated with the D_(4)receptor agonist PD168077 and/or the D_(4)receptor antagonist L745870,the NO synthase inhibitor NG-nitro-L-arginine-methyl ester(L-NAME)or the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one(ODQ).Total D_(4)receptor expression and its expression in the plasma membrane were investigated by immunoblotting in RPT cells from Wistar-Kyoto(WKY)rats and spontaneously hypertensive rats(SHRs).Results:Activation of D_(4)receptors with PD168077,inhibited NKA activity in RPT cells from WKY rats in a concentration-and time-dependent manner.The inhibitory effect of PD168077 on NKA activity was prevented by the addition of the D_(4)receptor antagonist L745870,which by itself had no effect.The NO synthase inhibitor L-NAME and the soluble guanylyl cyclase inhibitor ODQ,which by themselves had no effect on NKA activity,eliminated the inhibitory effect of PD168077 on NKA activity.Activation of D_(4)receptors also increased NO levels in the culture medium and cGMP levels in RPT cells.However,the inhibitory effect of D_(4)receptors on NKA activity was absent in RPT cells from SHRs,which could be related to decreased plasma membrane expression of D_(4)receptors in SHR RPT cells.Conclusions:Activation of D_(4)receptors directly inhibits NKA activity via the NO/cGMP signaling pathway in RPT cells from WKY rats but not SHRs.Aberrant regulation of NKA activity in RPT cells may be involved in the pathogenesis of hypertension.展开更多
文摘Acetaminophen is a drug used to treat many conditions as headache, muscle aches, arthritis, backache, toothache, and fever between others, but collateral effects of this drug are not well known yet. Here is tested its effect on proximal tubule epithelium. Acetaminophen (APAP) at doses of 200, 500, 1000 and 1500 mg/Kg i.p. caused cell damage and changes in F-actin distribution in the proximal tubule of male Wistar rats. After 48 hours of treatment, the proximal tubule epithelium showed tumefaction and necrosis. Dose of 200 mg/kg decreased the F-actin and was observed a structure in patches in the basal cytoplasm of epithelial cells of the proximal tubule. This effect was increased depending on the administered dose. Dose of 1000 mg/kg produced the highest histological damage and changes in the actin cytoskeleton. Results of this study suggested that nephrotoxic damage produced by high doses of APAP included breakdown of cytoskeleton in proximal tubule epithelium.
文摘Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote renal tubule regeneration in AKI through the regulation of the PTEN signaling pathway by miR-21.BMSCs were isolated and characterized,and their exosomes were purified.In vitro,renal tubular epithelial cell injury models were established,and the co-culture of exosomes and cells demonstrated enhanced cell proliferation and reduced apoptosis.In vivo,AKI animal models showed improved renal function and histopathological changes after exosome treatment.miR-21 was found to be upregulated in exosomes and recipient cells,targeting PTEN and activating the PI3K/AKT pathway.The signaling network also interacted with other pathways related to renal tubule regeneration.The study highlights the potential of exosome therapy for AKI and provides insights into the underlying molecular mechanisms,although further research is needed to address remaining challenges and translate these findings into clinical applications.
基金Supported by National Institutes of Health,No.DP2 OD008470Private funding was provided from the University of Notre Dame College of Science and Graduate Schoola generous donation to support stem cell research provided by the Gallagher Family
文摘Kidney disease is an escalating global health problem,for which the formulation of therapeutic approaches using stem cells has received increasing research attention.The complexity of kidney anatomy and function,which includes the diversity of renal cell types,poses formidable challenges in the identification of methods to generate replacement structures.Recent work using the zebrafish has revealed their high capacity to regenerate the integral working units of the kidney,known as nephrons,following acute injury.Here,we discuss these findings and explore the ways that zebrafish can be further utilized to gain a deeper molecular appreciation of renal stem cell biology,which may uncover important clues for regenerative medicine.
文摘Acute tubular necrosis(ATN)induced by ischemia is the most common insult to donor kidneysdestined for trarsplantation.ATN results from sweling and subsequent damage to cells lining thelkidney tubules.In this study,we demonstrate the capability of optical coherence tomography(OcT)to image the renal microst ructures of living human donor kidneys and potentially providea measure to det ermine the extent of A TN.We also found that Doppler-based OCT(i.e.,DOCT)reveals renal blood flow dynamics that is another major factor which could relate to post-transplant renal finction.All OCT/DoCT oberva tions were performed in a noninvasive,sterileand timely manner on intact human kidneys both prior to(er vivo)and following(in vivo)theirtransplantation.Our results indicate that this imaging model provides transplant surgeons withan objective visualization of the transplant lidneys prior and immediately post transplantation.
文摘Current dialysis systems are not perfect considering the low efficacy and cumbersome process of actual practice. To overcome these shortcomings, bioartificial kidneys using renal tubule cells and wearable dialysis are promising ESRD treatments available in the near future. Toward clinical application, however, there are so many obstacles for commercial use of them. In this review, current status of bioartificial kidneys such as the renal tubule cell assist device (RAD) and wearable dialysis devices is presented with the comparison to show the advantages and disadvantages.
文摘950350 Improving lithium clearance——a methodfor measuring sodium delivery of tubule in human.WANG Huamin(王化民),et al.Nephrol Div,1stTeach Hosp,Beijing Med Univ.Chin J Nephrol 1994;10(6):326-328.Based on the method for lithium clearance,we ob-served the relationship between serum lithium concen-tration at the fouth hour in the test and the representa-tive serum lithium concentration,and verified that
基金supported by the National Natural Science Foundation of China (81571396 and 81771528)Science, Technology and Innovation Commission of Shenzhen Municipality (JCYJ20170411090932146, JCYJ20170818110544730)。
文摘The mechanism of how SARS-CoV-2 causes severe multi-organ failure is largely unknown. Acute kidney injury(AKI) is one of the frequent organ damage in severe COVID-19 patients. Previous studies have shown that human renal tubule cells could be the potential host cells targeted by SARS-CoV-2. Traditional cancer cell lines or immortalized cell lines are genetically and phenotypically different from host cells. Animal models are widely used, but often fail to reflect a physiological and pathogenic status because of species tropisms. There is an unmet need for normal human epithelial cells for disease modeling. In this study, we successfully established long term cultures of normal human kidney proximal tubule epithelial cells(KPTECs) in 2 D and 3 D culture systems using conditional reprogramming(CR) and organoids techniques.These cells had the ability to differentiate and repair DNA damage, and showed no transforming property. Importantly, the CR KPTECs maintained lineage function with expression of specific transporters(SLC34 A3 and cubilin). They also expressed angiotensin-converting enzyme 2(ACE2), a receptor for SARS-CoV and SARS-CoV-2. In contrast, cancer cell line did not express endogenous SLC34 A3, cubilin and ACE2. Very interestingly, ACE2 expression was around twofold higher in 3 D organoids culture compared to that in 2 D CR culture condition. Pseudovirion assays demonstrated that SARS-CoV spike(S) protein was able to enter CR cells with luciferase reporter. This integrated 2 D CR and 3 D organoid cultures provide a physiological ex vivo model to study kidney functions, innate immune response of kidney cells to viruses, and a novel platform for drug discovery and safety evaluation.
文摘970375 Amino acid metabolism analysis and protec-tion against injury to isolated proximal tubules incu-bated with cyclosporin A. JIANG Tang(姜傥), etal. Kidney Instit, 1st Affili Hosp, Sun Yat-sen Med U-niv, Guangzhou, 510080. Chin J Nephrol 1996; 12(6):347-351. Objective: To study the mechanism of cyclosporin
文摘OBJECTIVE: To investigate the effect of L-arginine (L-arg) on early compensatory renal growth (CRG), tubulointerstitial accumulation of extracellular matrix (ECM), long term survival rate and renal scarring in rats with 5/6 nephrectomy (SNx). METHODS: The experiment included four groups of rats (n = 5 each group): (1) Sham group, (2) SNx group, (3) SNx + L-arg group, and (4) Sham + L-arg group (L-arg 1% in drinking water). Parameters related with CRG and early tubulointerstitial expression of ECM and alpha smooth muscle actin (alphaSMA) were evaluated by immunohistochemistry at day 30. The survival rate and the extent of renal scarring in the rats were observed at day 120. RESULTS: L-arg significantly increased the early CRG of SNx rats as determined by the wet kidney weight (P
基金National Key Research and Development Program of China(No.2020YFC2005000)Key Research and Development Program of Hunan province(No.2020WK2008)+3 种基金science and technology innovation Program of Hunan Province(No.2020RC5002)Natural Science Foundation of Hunan Province(Nos.2022JJ30070,2021JJ31130 and 2021JJ31057)Project of Health Commission of Hunan Province(Nos.A202303050036 and 202104101009)"Yiluqihang Shenmingyuanyang"medical development and Scientific Research Fund project on Kidney Diseases(No.SMYY20220301001)
文摘Background:Ischemic acute kidney injury(AKI)is a common syndrome associated with considerable mortality and healthcare costs.Up to now,the underlying pathogenesis of ischemic AKI remains incompletely understood,and specific strategies for early diagnosis and treatment of ischemic AKI are still lacking.Here,this study aimed to define the transcriptomic landscape of AKI patients through single-cell RNA sequencing(scRNA-seq)analysis in kidneys.Methods:In this study,scRNA-seq technology was applied to kidneys from two ischemic AKI patients,and three human public scRNA-seq datasets were collected as controls.Differentially expressed genes(DEGs)and cell clusters of kidneys were determined.Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis,as well as the ligand-receptor interaction between cells,were performed.We also validated several DEGs expression in kidneys from human ischemic AKI and ischemia/reperfusion(I/R)injury induced AKI mice through immunohistochemistry staining.Results:15 distinct cell clusters were determined in kidney from subjects of ischemic AKI and control.The injured proximal tubules(PT)displayed a proapoptotic and proinflammatory phenotype.PT cells of ischemic AKI had up-regulation of novel pro-apoptotic genes including USP47,RASSF4,EBAG9,IER3,SASH1,SEPTIN7,and NUB1,which have not been reported in ischemic AKI previously.Several hub genes were validated in kidneys from human AKI and renal I/R injury mice,respectively.Furthermore,PT highly expressed DEGs enriched in endoplasmic reticulum stress,autophagy,and retinoic acid-inducible gene I(RIG-I)signaling.DEGs overexpressed in other tubular cells were primarily enriched in nucleotide-binding and oligomerization domain(NOD)-like receptor signaling,estrogen signaling,interleukin(IL)-12 signaling,and IL-17 signaling.Overexpressed genes in kidney-resident immune cells including macrophages,natural killer T(NKT)cells,monocytes,and dendritic cells were associated with leukocyte activation,chemotaxis,cell adhesion,and complement activation.In addition,the ligand-receptor interactions analysis revealed prominent communications between macrophages and monocytes with other cells in the process of ischemic AKI.Conclusion:Together,this study reveals distinct cell-specific transcriptomic atlas of kidney in ischemic AKI patients,altered signaling pathways,and potential cell-cell crosstalk in the development of AKI.These data reveal new insights into the pathogenesis and potential therapeutic strategies in ischemic AKI.
基金the National Key R&D Program of China(2018YFC1312700)the National Naturai Science Foundation of China(831730043)+4 种基金the Program of Innovative Research Team of the National Natural Science Foundation(81721001)Program for Changjiang Scholars and Innovative Research Team in University(IRT1216)Key Research and Development Projects of Science and Technology Innovation of Social and People's Livelihood in Chongqing City,(cstc2018jscx-mszdX0024)Clinical Medical Research Talent Training Program from The Third Military Medical University(2018XLCi012)National Institutes of Health,USA(P01HL074940,DK039308,and DK119652).
文摘Objective:Dopamine,via its receptors,plays a vital role in the maintenance of blood pressure by modulating renal sodium transport.However,the role of the D_(4)dopamine receptor(D_(4)receptor)in renal proximal tubules(PRTs)is still unclear.This study aimed to verify the hypothesis that activation of D_(4)receptor directly inhibits the activity of the Na+-K+-ATPase(NKA)in RPT cells.Methods:NKA activity,nitric oxide(NO)and cyclic guanosine monophosphate(cGMP)levels were measured in RPT cells treated with the D_(4)receptor agonist PD168077 and/or the D_(4)receptor antagonist L745870,the NO synthase inhibitor NG-nitro-L-arginine-methyl ester(L-NAME)or the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one(ODQ).Total D_(4)receptor expression and its expression in the plasma membrane were investigated by immunoblotting in RPT cells from Wistar-Kyoto(WKY)rats and spontaneously hypertensive rats(SHRs).Results:Activation of D_(4)receptors with PD168077,inhibited NKA activity in RPT cells from WKY rats in a concentration-and time-dependent manner.The inhibitory effect of PD168077 on NKA activity was prevented by the addition of the D_(4)receptor antagonist L745870,which by itself had no effect.The NO synthase inhibitor L-NAME and the soluble guanylyl cyclase inhibitor ODQ,which by themselves had no effect on NKA activity,eliminated the inhibitory effect of PD168077 on NKA activity.Activation of D_(4)receptors also increased NO levels in the culture medium and cGMP levels in RPT cells.However,the inhibitory effect of D_(4)receptors on NKA activity was absent in RPT cells from SHRs,which could be related to decreased plasma membrane expression of D_(4)receptors in SHR RPT cells.Conclusions:Activation of D_(4)receptors directly inhibits NKA activity via the NO/cGMP signaling pathway in RPT cells from WKY rats but not SHRs.Aberrant regulation of NKA activity in RPT cells may be involved in the pathogenesis of hypertension.
