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Sorensen CM, Salomonsson M, Lubberding AF, Holstein‐Rathlou N. The renal vasodilatation from β-adrenergic activation in vivo in rats is not driven by K V7 and BK Ca channels. Exp Physiol 2024; 109:791-803. [PMID: 38460127 PMCID: PMC11061631 DOI: 10.1113/ep091618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/21/2024] [Indexed: 03/11/2024]
Abstract
The mechanisms behind renal vasodilatation elicited by stimulation of β-adrenergic receptors are not clarified. As several classes of K channels are potentially activated, we tested the hypothesis that KV7 and BKCa channels contribute to the decreased renal vascular tone in vivo and in vitro. Changes in renal blood flow (RBF) during β-adrenergic stimulation were measured in anaesthetized rats using an ultrasonic flow probe. The isometric tension of segmental arteries from normo- and hypertensive rats and segmental arteries from wild-type mice and mice lacking functional KV7.1 channels was examined in a wire-myograph. The β-adrenergic agonist isoprenaline increased RBF significantly in vivo. Neither activation nor inhibition of KV7 and BKCa channels affected the β-adrenergic RBF response. In segmental arteries from normo- and hypertensive rats, inhibition of KV7 channels significantly decreased the β-adrenergic vasorelaxation. However, inhibiting BKCa channels was equally effective in reducing the β-adrenergic vasorelaxation. The β-adrenergic vasorelaxation was not different between segmental arteries from wild-type mice and mice lacking KV7.1 channels. As opposed to rats, inhibition of KV7 channels did not affect the murine β-adrenergic vasorelaxation. Although inhibition and activation of KV7 channels or BKCa channels significantly changed baseline RBF in vivo, none of the treatments affected β-adrenergic vasodilatation. In isolated segmental arteries, however, inhibition of KV7 and BKCa channels significantly reduced the β-adrenergic vasorelaxation, indicating that the regulation of RBF in vivo is driven by several actors in order to maintain an adequate RBF. Our data illustrates the challenge in extrapolating results from in vitro to in vivo conditions.
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Affiliation(s)
- Charlotte Mehlin Sorensen
- Department of Biomedical Sciences, Physiology of Circulation, Kidney and LungUniversity of CopenhagenCopenhagenDenmark
| | | | - Anniek Frederike Lubberding
- Department of Biomedical Sciences, Physiology of Inflammation, Metabolism and OxidationUniversity of CopenhagenCopenhagenDenmark
| | - Niels‐Henrik Holstein‐Rathlou
- Department of Biomedical Sciences, Physiology of Circulation, Kidney and LungUniversity of CopenhagenCopenhagenDenmark
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2
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Cabral B, Bortolin RH, Gonçalves TAF, Maciel PMP, de Arruda AV, de Carvalho TG, Abboud KY, Alves JSF, Cordeiro LMC, de Medeiros IA, de Rezende AA, Zucolotto SM. Hypoglycemic and Vasorelaxant Effect of Passiflora edulis Fruit Peel By-Product. PLANT FOODS FOR HUMAN NUTRITION (DORDRECHT, NETHERLANDS) 2021; 76:466-471. [PMID: 34581915 DOI: 10.1007/s11130-021-00921-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
Passiflora edulis fo. flavicarpa (Passifloraceae) is popularly known as yellow passion fruit and its fruit peels are considered a rich by-product in bioactive compounds which has greatly beneficial health properties. The objective of this study was to evaluate the effects of P. edulis fruit peel extracts in a type 1 diabetes model and the potential vasorelaxant effect. The aqueous and hydroethanolic extracts were obtained from P. edulis fruit peels and orientin and isorientin flavonoids were identified in both extracts through ultra-high performance liquid chromatography. Pectin was only identified in the aqueous extract by high-performance steric exclusion chromatography and nuclear magnetic resonance. Regarding the vascular system, the hydroethanolic extract showed better vasorelaxant effects in the mesenteric artery rings when compared to the aqueous extract. These effects mainly occur by opening the potassium channels. In the type 1 diabetes model, extracts at doses of 400 and 600 mg/kg were able to restore the effect of insulin in diabetic rats which were not responding to its action. The antidiabetic effect was more significant for the aqueous extract. Thus, the results suggest that the hydroethanolic and aqueous extracts have greater potential to be used to treat cardiovascular diseases such as hypertension and as a hypoglycemic agent, respectively. Taken together, P. edulis fruit peel extracts proved to be a source of valuable bioactive raw material to produce nutraceuticals or pharmaceutical products.
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Affiliation(s)
- Bárbara Cabral
- PNBIO, Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande Do Norte (UFRN), Natal, RN, Brazil
| | - Raul Hernandes Bortolin
- Department of Clinical and Toxicological Analyses, Federal University of Rio Grande Do Norte, Avenue Gen. Gustavo Cordeiro de Faria, Natal, RN, Brazil
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Science, University of Sao Paulo, Sao Paulo, SP, Brazil
| | | | | | - Alinne Villar de Arruda
- Department of Pharmaceutical Sciences, Federal University of Paraíba, João Pessoa, PB, Brazil
| | | | - Kahlile Youssef Abboud
- Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, PR, Brazil
| | - Jovelina Samara Ferreira Alves
- PNBIO, Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande Do Norte (UFRN), Natal, RN, Brazil
| | - Lucimara M C Cordeiro
- Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, PR, Brazil
| | | | - Adriana Augusto de Rezende
- Department of Clinical and Toxicological Analyses, Federal University of Rio Grande Do Norte, Avenue Gen. Gustavo Cordeiro de Faria, Natal, RN, Brazil
| | - Silvana Maria Zucolotto
- PNBIO, Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande Do Norte (UFRN), Natal, RN, Brazil.
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Pinilla E, Sánchez A, Martínez MP, Muñoz M, García‐Sacristán A, Köhler R, Prieto D, Rivera L. Endothelial K Ca 1.1 and K Ca 3.1 channels mediate rat intrarenal artery endothelium-derived hyperpolarization response. Acta Physiol (Oxf) 2021; 231:e13598. [PMID: 33314681 DOI: 10.1111/apha.13598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/30/2022]
Abstract
AIM Endothelium-derived hyperpolarization (EDH)-mediated response plays an essential role in the control of kidney preglomerular circulation, but the identity of the K+ channels involved in this response is still controversial. We hypothesized that large- (KCa 1.1), intermediate- (KCa 3.1) and small (KCa 2.3) -conductance Ca2+ -activated K+ (KCa ) channels are expressed in the endothelium of the preglomerular circulation and participate in the EDH-mediated response. METHODS We study the functional expression of different K+ channels in non-cultured, freshly isolated native endothelial cells (ECs) of rat intrarenal arteries using immunofluorescence and the patch-clamp technique. We correlate this with vasorelaxant responses ex vivo using wire myography. RESULTS Immunofluorescence revealed the expression of KCa 1.1, KCa 3.1 and KCa 2.3 channels in ECs. Under voltage-clamp conditions, acetylcholine induced a marked increase in the outward currents in these cells, sensitive to the blockade of KCa 1.1, KCa 3.1 and KCa 2.3 channels respectively. Isometric myography experiments, under conditions of endothelial nitric oxide synthase and cyclooxygenase inhibition, showed that blockade either of KCa 1.1 or KCa 3.1 channels was able to reduce the endothelium-derived vasorelaxation of isolated interlobar arteries, while their combined blockade completely abolished it. In contrast, blockade of KCa 2.3 channels did not reduce this vasorelaxant response, despite being functionally expressed in the endothelial cells. CONCLUSION This study shows that KCa 1.1 and KCa 3.1 channels are functionally expressed at the renal vascular endothelium and play a central role in the EDH-mediated relaxation of kidney preglomerular arteries, which is important in the control of renal blood flow and glomerular filtration rate.
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Affiliation(s)
- Estéfano Pinilla
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology Aarhus University Aarhus Denmark
| | - Ana Sánchez
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
| | - María P. Martínez
- Department of Compared Anatomy and Pathological Anatomy, Faculty of Veterinary Complutense University of Madrid Madrid Spain
| | - Mercedes Muñoz
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
| | - Albino García‐Sacristán
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
| | - Ralf Köhler
- Aragonese Agency for Investigation and Development & IACS/IIS Translational ResearchMiguel Servet Hospital Zaragoza Spain
| | - Dolores Prieto
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
| | - Luis Rivera
- Departament of Physiology, Faculty of Pharmacy Complutense University of Madrid Madrid Spain
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4
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Nakade UP, Sharma A, Kumari P, Bhatiya S, Nair SV, Karikaran KN, Sharma V, Choudhury S, Garg SK. Functional and molecular characterization of endothelium-dependent and endothelium-independent relaxant pathways in uterine artery of non-pregnant buffaloes. Naunyn Schmiedebergs Arch Pharmacol 2019; 393:225-241. [PMID: 31494705 DOI: 10.1007/s00210-019-01726-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 09/02/2019] [Indexed: 02/05/2023]
Abstract
Present study was undertaken to unravel the endothelium-dependent and endothelium-independent relaxant pathways in uterine artery of non-pregnant buffaloes. Isometric tension of arterial rings was recorded using data acquisition system based polyphysiograph. Acetylcholine (ACh) produced endothelium-dependent vasorelaxation by releasing nitric oxide (NO), and inhibition of nitric oxide synthase (NOS) by L-NAME (300 μM) significantly (P < 0.05) reduced the NO release and thereby the vasorelaxant effect of ACh. However, L-NMMA, another NOS inhibitor, and PTIO, a NO scavenger, did not have any additional inhibitory effect on NO and ACh-induced vasorelaxation. Cyclooxygenase (COX) inhibitor (indomethacin) alone did not have any inhibitory action on vasorelaxant response to ACh; however, simultaneous inhibition of COX and NOS enzymes significantly (P < 0.05) attenuated the relaxant response indicating the concurrent release of these two mediators in regulating ACh-induced relaxation. Besides NOS and COX-derived metabolites (EDRF), small (SKCa) and intermediate (IKCa) conductance K+ channels being the members of EDHF play predominant role in mediating ACh-induced vasorelaxation. Using different molecular tools, existence of eNOS, COX-1, and,IKCa in the endothelium, BKCa in vascular smooth muscle, and SKCa in both endothelium and vascular smooth muscle was demonstrated in buffalo uterine artery. Gene sequencing of COX-1 and SKCa genes in uterine artery of buffaloes showed more than 97% structural similarity with ovine (Ovis aries), caprine (Capra hircus), and Indian cow (Bos indicus). Endothelium-independent nitrovasodilator, sodium nitroprusside (SNP), produced vasorelaxation which was sensitive to blockade by soluble guanylate cyclase (sGC) inhibitor (ODQ), thus suggesting the important role of cGMP/PKG pathways in uterine vasorelaxation in buffaloes. Taken together, it is concluded that both endothelium-dependent (EDHF and EDRF) and endothelium-independent (sGC-cGMP) relaxant pathways are present in uterine arteries of non-pregnant buffaloes, and they differently contribute to vasorelaxation during non-pregnant state.
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Affiliation(s)
- Udayraj P Nakade
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Abhishek Sharma
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Priyambada Kumari
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Shirish Bhatiya
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Sooraj V Nair
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - K N Karikaran
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Vipin Sharma
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Soumen Choudhury
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Satish Kumar Garg
- Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India.
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5
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Ronn J, Jensen EP, Wewer Albrechtsen NJ, Holst JJ, Sorensen CM. Glucagon-like peptide-1 acutely affects renal blood flow and urinary flow rate in spontaneously hypertensive rats despite significantly reduced renal expression of GLP-1 receptors. Physiol Rep 2018; 5. [PMID: 29233907 PMCID: PMC5727271 DOI: 10.14814/phy2.13503] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/17/2017] [Accepted: 10/19/2017] [Indexed: 02/06/2023] Open
Abstract
Glucagon‐like peptide‐1 (GLP‐1) is an incretin hormone increasing postprandial insulin release. GLP‐1 also induces diuresis and natriuresis in humans and rodents. The GLP‐1 receptor is extensively expressed in the renal vascular tree in normotensive rats where acute GLP‐1 treatment leads to increased mean arterial pressure (MAP) and increased renal blood flow (RBF). In hypertensive animal models, GLP‐1 has been reported both to increase and decrease MAP. The aim of this study was to examine expression of renal GLP‐1 receptors in spontaneously hypertensive rats (SHR) and to assess the effect of acute intrarenal infusion of GLP‐1. We hypothesized that GLP‐1 would increase diuresis and natriuresis and reduce MAP in SHR. Immunohistochemical staining and in situ hybridization for the GLP‐1 receptor were used to localize GLP‐1 receptors in the kidney. Sevoflurane‐anesthetized normotensive Sprague–Dawley rats and SHR received a 20 min intrarenal infusion of GLP‐1 and changes in MAP, RBF, heart rate, dieresis, and natriuresis were measured. The vasodilatory effect of GLP‐1 was assessed in isolated interlobar arteries from normo‐ and hypertensive rats. We found no expression of GLP‐1 receptors in the kidney from SHR. However, acute intrarenal infusion of GLP‐1 increased MAP, RBF, dieresis, and natriuresis without affecting heart rate in both rat strains. These results suggest that the acute renal effects of GLP‐1 in SHR are caused either by extrarenal GLP‐1 receptors activating other mechanisms (e.g., insulin) to induce the renal changes observed or possibly by an alternative renal GLP‐1 receptor.
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Affiliation(s)
- Jonas Ronn
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elisa P Jensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M Sorensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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6
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Salomonsson M, Brasen JC, Sorensen CM. Role of renal vascular potassium channels in physiology and pathophysiology. Acta Physiol (Oxf) 2017; 221:14-31. [PMID: 28371470 DOI: 10.1111/apha.12882] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/10/2016] [Accepted: 03/22/2017] [Indexed: 12/31/2022]
Abstract
The control of renal vascular tone is important for the regulation of salt and water balance, blood pressure and the protection against damaging elevated glomerular pressure. The K+ conductance is a major factor in the regulation of the membrane potential (Vm ) in vascular smooth muscle (VSMC) and endothelial cells (EC). The vascular tone is controlled by Vm via its effect on the opening probability of voltage-operated Ca2+ channels (VOCC) in VSMC. When K+ conductance increases Vm becomes more negative and vasodilation follows, while deactivation of K+ channels leads to depolarization and vasoconstriction. K+ channels in EC indirectly participate in the control of vascular tone by endothelium-derived vasodilation. Therefore, by regulating the tone of renal resistance vessels, K+ channels have a potential role in the control of fluid homoeostasis and blood pressure as well as in the protection of the renal parenchyma. The main classes of K+ channels (calcium activated (KCa ), inward rectifier (Kir ), voltage activated (Kv ) and ATP sensitive (KATP )) have been found in the renal vessels. In this review, we summarize results available in the literature and our own studies in the field. We compare the ambiguous in vitro and in vivo results. We discuss the role of single types of K+ channels and the integrated function of several classes. We also deal with the possible role of renal vascular K+ channels in the pathophysiology of hypertension, diabetes mellitus and sepsis.
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Affiliation(s)
| | - J. C. Brasen
- Department of Electrical Engineering; Technical University of Denmark; Kgs. Lyngby Denmark
| | - C. M. Sorensen
- Department of Biomedical Sciences; Division of Renal and Vascular Physiology; University of Copenhagen; Copenhagen Denmark
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7
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Savignano FA, Crajoinas RO, Pacheco BPM, Campos LCG, Shimizu MHM, Seguro AC, Girardi ACC. Attenuated diuresis and natriuresis in response to glucagon-like peptide-1 in hypertensive rats are associated with lower expression of the glucagon-like peptide-1 receptor in the renal vasculature. Eur J Pharmacol 2017; 811:38-47. [PMID: 28576404 DOI: 10.1016/j.ejphar.2017.05.054] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 05/25/2017] [Accepted: 05/29/2017] [Indexed: 12/26/2022]
Abstract
Accumulating evidence from clinical and experimental studies indicates that the incretin glucagon-like peptide-1 (GLP-1) elicits blood-pressure lowering effects via its diuretic, natriuretic and vasodilatory properties. The present study investigated whether acute infusion of GLP-1 induces diuresis and natriuresis in spontaneously hypertensive rats (SHRs). Additionally, we examined whether GLP-1 influences the vascular reactivity of the renal arteries of normotensive and hypertensive rats and elucidated the underlying mechanisms. We found that the increase in urinary output and urinary sodium excretion in response to systemic infusion of GLP-1 for 30min in SHRs was much less pronounced than in normotensive rats. The diuretic and natriuretic actions of GLP-1 in normotensive rats were accompanied by increases in GFR and RBF and a reduction in RVR through activation of the cAMP signaling pathway. However, no changes in renal hemodynamics were observed in SHRs. Similarly, GLP-1 induced an endothelium-independent relaxation effect in the renal arteries of normotensive rats, whereas the renal vasculature of SHRs was unresponsive to this vasodilator. The absence of a GLP-1-induced renal artery vasodilator effect in SHRs was associated with lower expression of the GLP-1 receptor, blunted GLP-1-induced increases in cAMP production and higher activity and expression of the GLP-1 inactivating enzyme dipeptidyl peptidase IV relative to the renal arteries of normotensive rats. Collectively, these results demonstrate that the renal acute responses to GLP-1 are attenuated in SHRs. Thus, chronic treatment with incretin-based agents may rely upon the upregulation of GLP-1/GLP-1 receptor signaling in the kidneys of hypertensive patients and experimental models.
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Affiliation(s)
- Fernanda A Savignano
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Renato O Crajoinas
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Bruna P M Pacheco
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Luciene C G Campos
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Maria Heloisa M Shimizu
- Department of Nephrology (LIM-12), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Antonio Carlos Seguro
- Department of Nephrology (LIM-12), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Adriana C C Girardi
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil.
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8
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Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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9
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Jensen LJ, Nielsen MS, Salomonsson M, Sørensen CM. T-type Ca 2+ channels and autoregulation of local blood flow. Channels (Austin) 2017; 11:183-195. [PMID: 28055302 DOI: 10.1080/19336950.2016.1273997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
L-type voltage gated Ca2+ channels are considered to be the primary source of calcium influx during the myogenic response. However, many vascular beds also express T-type voltage gated Ca2+ channels. Recent studies suggest that these channels may also play a role in autoregulation. At low pressures (40-80 mmHg) T-type channels affect myogenic responses in cerebral and mesenteric vascular beds. T-type channels also seem to be involved in skeletal muscle autoregulation. This review discusses the expression and role of T-type voltage gated Ca2+ channels in the autoregulation of several different vascular beds. Lack of specific pharmacological inhibitors has been a huge challenge in the field. Now the research has been strengthened by genetically modified models such as mice lacking expression of T-type voltage gated Ca2+ channels (CaV3.1 and CaV3.2). Hopefully, these new tools will help further elucidate the role of voltage gated T-type Ca2+ channels in autoregulation and vascular function.
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Affiliation(s)
- Lars Jørn Jensen
- a Departments of Veterinary Clinical and Animal Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Morten Schak Nielsen
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Max Salomonsson
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Charlotte Mehlin Sørensen
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
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10
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Sympathetic denervation facilitates L-type Ca2+ channel activation in renal but not in mesenteric resistance arteries. J Hypertens 2016; 34:692-703. [PMID: 26841239 DOI: 10.1097/hjh.0000000000000856] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Sympathetic denervation enhances agonist-induced vasoconstriction. This effect may involve altered function of signaling mechanisms such as Rho kinase (Rock) and L-type Ca channels downstream from vasoconstrictor receptors. We tested if enhanced Rock and L-type calcium channel activation contribute to exaggerated norepinephrine-induced vasoconstrictions in renal and mesenteric resistance arteries after sympathectomy. METHODS Rats underwent neonatal sympathectomy or sham sympathectomy. Resistance arteries were investigated by small vessel myography. Vascular Rock and L-type Ca channel expression as well as Rock activation were investigated by quantitative real-time PCR and Western blot. Vascular smooth muscle cell (VSMC) membrane potential was recorded with microelectrodes. RESULTS Sympathetic denervation enhanced norepinephrine sensitivity in renal and mesenteric arteries. Both, Rock inhibition or L-type Ca inhibition shifted the norepinephrine concentration-response curve to the right. This effect was more pronounced in renal than in mesenteric arteries from sympathectomized vs. sham-sympathectomized animals. The L-type Ca channel activator S-(-)-BayK8644 elicited strong vasoconstrictions only in renal arteries from sympathectomized rats. Rock activity and L-type Ca channel α-subunit expression were similar in renal arteries from sympathectomized and sham-sympathectomized animals. VSMC membrane potential was -57.5 ± 2.0 and -64.3 ± 0.3 mV (P < 0.01), respectively, in renal arteries from sympathectomized and from sham-sympathectomized rats. Depolarization enhanced and KATP channel activation abolished S-(-)-BayK8644-induced contractions in renal arteries from sympathectomized rats. CONCLUSION Sympathetic denervation enhances L-type Ca channel-dependent signaling in renal but not in mesenteric arteries. This effect may be partly explained by the decreased VSMC membrane potential in denervated renal arteries.
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No apparent role for T-type Ca²⁺ channels in renal autoregulation. Pflugers Arch 2015; 468:541-50. [PMID: 26658945 DOI: 10.1007/s00424-015-1770-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/03/2015] [Indexed: 10/22/2022]
Abstract
Renal autoregulation protects glomerular capillaries against increases in renal perfusion pressure (RPP). In the mesentery, both L- and T-type calcium channels are involved in autoregulation. L-type calcium channels participate in renal autoregulation, but the role of T-type channels is not fully elucidated due to lack of selective pharmacological inhibitors. The role of T- and L-type calcium channels in the response to acute increases in RPP in T-type channel knockout mice (CaV3.1) and normo- and hypertensive rats was examined. Changes in afferent arteriolar diameter in the kidneys from wild-type and CaV3.1 knockout mice were assessed. Autoregulation of renal blood flow was examined during acute increases in RPP in normo- and hypertensive rats under pharmacological blockade of T- and L-type calcium channels using mibefradil (0.1 μM) and nifedipine (1 μM). In contrast to the results from previous pharmacological studies, genetic deletion of T-type channels CaV3.1 did not affect renal autoregulation. Pharmacological blockade of T-type channels using concentrations of mibefradil which specifically blocks T-type channels also had no effect in wild-type or knockout mice. Blockade of L-type channels significantly attenuated renal autoregulation in both strains. These findings are supported by in vivo studies where blockade of T-type channels had no effect on changes in the renal vascular resistance after acute increases in RPP in normo- and hypertensive rats. These findings show that genetic deletion of T-type channels CaV3.1 or treatment with low concentrations of mibefradil does not affect renal autoregulation. Thus, T-type calcium channels are not involved in renal autoregulation in response to acute increases in RPP.
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Salomonsson M, Brasen JC, Braunstein TH, Hagelqvist P, Holstein-Rathlou NH, Sorensen CM. K(V)7.4 channels participate in the control of rodent renal vascular resting tone. Acta Physiol (Oxf) 2015; 214:402-14. [PMID: 25965962 DOI: 10.1111/apha.12525] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/19/2015] [Accepted: 05/06/2015] [Indexed: 01/07/2023]
Abstract
AIM We tested the hypothesis that K(V)7 channels contribute to basal renal vascular tone and that they participate in agonist-induced renal vasoconstriction or vasodilation. METHODS KV 7 channel subtypes in renal arterioles were characterized by immunofluorescence. Renal blood flow (RBF) was measured using an ultrasonic flow probe. The isometric tension of rat interlobar arteries was examined in a wire myograph. Mice afferent arteriolar diameter was assessed utilizing the perfused juxtamedullary nephron technique. RESULTS Immunofluorescence revealed that K(V)7.4 channels were expressed in rat afferent arterioles. The K(V)7 blocker XE991 dose-dependently increased the isometric tension of rat interlobar arteries and caused a small (approx. 4.5%) RBF reduction in vivo. Nifedipine abolished these effects. Likewise, XE991 reduced mouse afferent arteriolar diameter by approx. 5%. The K(V)7.2-5 stimulator flupirtine dose-dependently relaxed isolated rat interlobar arteries and increased (approx. 5%) RBF in vivo. The RBF responses to NE or Ang II administration were not affected by pre-treatment with XE991 or flupirtine. XE991 pre-treatment caused a minor augmentation of the acetylcholine-induced increase in RBF, while flupirtine pre-treatment did not affect this response. CONCLUSION It is concluded that K(V)7 channels, via nifedipine sensitive channels, have a role in the regulation of basal renal vascular tone. There is no indication that K(V)7 channels have an effect on agonist-induced renal vasoconstriction while there is a small effect on acetylcholine-induced vasodilation.
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Affiliation(s)
- M. Salomonsson
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - J. C. Brasen
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Biomedical Engineering; Department of Electrical Engineering; Technical University of Denmark; Lyngby Denmark
| | - T. H. Braunstein
- Danish National Research Foundation Center for Cardiac Arrhythmia; University of Copenhagen; Copenhagen Denmark
| | - P. Hagelqvist
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - N.-H. Holstein-Rathlou
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Danish National Research Foundation Center for Cardiac Arrhythmia; University of Copenhagen; Copenhagen Denmark
| | - C. M. Sorensen
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
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13
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Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Jensen EP, Poulsen SS, Kissow H, Holstein-Rathlou NH, Deacon CF, Jensen BL, Holst JJ, Sorensen CM. Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow. Am J Physiol Renal Physiol 2015; 308:F867-77. [PMID: 25656368 DOI: 10.1152/ajprenal.00527.2014] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/03/2015] [Indexed: 01/04/2023] Open
Abstract
Glucagon-like peptide (GLP)-1 has a range of extrapancreatic effects, including renal effects. The mechanisms are poorly understood, but GLP-1 receptors have been identified in the kidney. However, the exact cellular localization of the renal receptors is poorly described. The aim of the present study was to localize renal GLP-1 receptors and describe GLP-1-mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and that activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using (125)I-labeled GLP-1, (125)I-labeled exendin-4 (GLP-1 analog), and (125)I-labeled exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1-mediated effects on blood pressure, renal blood flow (RBF), heart rate, renin secretion, urinary flow rate, and Na(+) and K(+) excretion were investigated in anesthetized rats. Effects of GLP-1 on afferent arterioles were investigated in isolated mouse kidneys. Specific binding of (125)I-labeled GLP-1, (125)I-labeled exendin-4, and (125)I-labeled exendin 9-39 was observed in the renal vasculature, including afferent arterioles. Infusion of GLP-1 increased blood pressure, RBF, and urinary flow rate significantly in rats. Heart rate and plasma renin concentrations were unchanged. Exendin 9-39 inhibited the increase in RBF. In isolated murine kidneys, GLP-1 and exendin-4 significantly reduced the autoregulatory response of afferent arterioles in response to stepwise increases in pressure. We conclude that GLP-1 receptors are located in the renal vasculature, including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases RBF in normotensive rats.
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Affiliation(s)
- Elisa P Jensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Steen S Poulsen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | | | - Carolyn F Deacon
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Boye L Jensen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Charlotte M Sorensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark;
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Zhang Z, Li M, Lu R, Alioua A, Stefani E, Toro L. The angiotensin II type 1 receptor (AT1R) closely interacts with large conductance voltage- and Ca2+-activated K+ (BK) channels and inhibits their activity independent of G-protein activation. J Biol Chem 2014; 289:25678-89. [PMID: 25070892 DOI: 10.1074/jbc.m114.595603] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Angiotensin II (ANG-II) and BK channels play important roles in the regulation of blood pressure. In arterial smooth muscle, ANG-II inhibits BK channels, but the underlying molecular mechanisms are unknown. Here, we first investigated whether ANG-II utilizes its type 1 receptor (AT1R) to modulate BK activity. Pharmacological, biochemical, and molecular evidence supports a role for AT1R. In renal arterial myocytes, the AT1R antagonist losartan (10 μM) abolished the ANG-II (1 μM)-induced reduction of whole cell BK currents, and BK channels and ANG-II receptors were found to co-localize at the cell periphery. We also found that BK inhibition via ANG-II-activated AT1R was independent of G-protein activation (assessed with 500 μM GDPβS). In BK-expressing HEK293T cells, ANG-II (1 μM) also induced a reduction of BK currents, which was contingent on AT1R expression. The molecular mechanisms of AT1R and BK channel coupling were investigated in co-transfected cells. Co-immunoprecipitation showed formation of a macromolecular complex, and live immunolabeling demonstrated that both proteins co-localized at the plasma membrane with high proximity indexes as in arterial myocytes. Consistent with a close association, we discovered that the sole AT1R expression could decrease BK channel voltage sensitivity. Truncated BK proteins revealed that the voltage-sensing conduction cassette is sufficient for BK-AT1R association. Finally, C-terminal yellow and cyan fluorescent fusion proteins, AT1R-YFP and BK-CFP, displayed robust co-localized Förster resonance energy transfer, demonstrating intermolecular interactions at their C termini. Overall, our results strongly suggest that AT1R regulates BK channels through a close protein-protein interaction involving multiple BK regions and independent of G-protein activation.
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Affiliation(s)
- Zhu Zhang
- From the Departments of Anesthesiology
| | - Min Li
- From the Departments of Anesthesiology
| | - Rong Lu
- From the Departments of Anesthesiology
| | | | - Enrico Stefani
- From the Departments of Anesthesiology, Physiology, the Brain Research Institute, and the Cardiovascular Research Laboratory, University of California, Los Angeles, California 90095
| | - Ligia Toro
- From the Departments of Anesthesiology, the Brain Research Institute, and the Cardiovascular Research Laboratory, University of California, Los Angeles, California 90095 Molecular and Medical Pharmacology, and
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Sachse G, Faulhaber J, Seniuk A, Ehmke H, Pongs O. Smooth muscle BK channel activity influences blood pressure independent of vascular tone in mice. J Physiol 2014; 592:2563-74. [PMID: 24687584 DOI: 10.1113/jphysiol.2014.272880] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The large conductance voltage- and Ca(2+)-activated K(+) (BK) channel is an important determinant of vascular tone and contributes to blood pressure regulation. Both activities depend on the ancillary BKβ1 subunit. To determine the significance of smooth muscle BK channel activity for blood pressure regulation, we investigated the potential link between changes in arterial tone and altered blood pressure in BKβ1 knockout (BKβ1(-/-)) mice from three different genetically defined strains. While vascular tone was consistently increased in all BKβ1(-/-) mice independent of genetic background, BKβ1(-/-) strains exhibited increased (strain A), unaltered (strain B) or decreased (strain C) mean arterial blood pressures compared to their corresponding BKβ1(+/+) controls. In agreement with previous data on aldosterone regulation by renal/adrenal BK channel function, BKβ1(-/-) strain A mice have increased plasma aldosterone and increased blood pressure. Consistently, blockade of mineralocorticoid receptors by spironolactone treatment reversibly restored the elevated blood pressure to the BKβ1(+/+) strain A level. In contrast, loss of BKβ1 did not affect plasma aldosterone in strain C mice. Smooth muscle-restricted restoration of BKβ1 expression increased blood pressure in BKβ1(-/-) strain C mice, implying that impaired smooth muscle BK channel activity lowers blood pressure in these animals. We conclude that BK channel activity directly affects vascular tone but influences blood pressure independent of this effect via different pathways.
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Affiliation(s)
- Gregor Sachse
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie, Falkenried 94, D-20251, Hamburg, Germany Department of Physiology, Anatomy and Genetics, South Parks Road, Oxford, OX1 3QX, UK
| | - Jörg Faulhaber
- Institut für Zelluläre und Integrative Physiologie, UKE, Martinistr. 52, D-20246, Hamburg, Germany
| | - Anika Seniuk
- Institut für Zelluläre und Integrative Physiologie, UKE, Martinistr. 52, D-20246, Hamburg, Germany
| | - Heimo Ehmke
- Institut für Zelluläre und Integrative Physiologie, UKE, Martinistr. 52, D-20246, Hamburg, Germany
| | - Olaf Pongs
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie, Falkenried 94, D-20251, Hamburg, Germany Institut für Physiologie (Geb 56), Universität des Saarlandes, 66421, Homburg/Saar, Germany
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17
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Shimizu S, Saito M, Oiwa H, Ohmasa F, Tsounapi P, Oikawa R, Dimitriadis F, Martin DT, Satoh I, Kinoshita Y, Tomita S. Olmesartan ameliorates urinary dysfunction in the spontaneously hypertensive rat via recovering bladder blood flow and decreasing oxidative stress. Neurourol Urodyn 2013; 33:350-7. [DOI: 10.1002/nau.22405] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/08/2013] [Indexed: 12/25/2022]
Affiliation(s)
- Shogo Shimizu
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Motoaki Saito
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Harunori Oiwa
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Fumiya Ohmasa
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Panagiota Tsounapi
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Ryo Oikawa
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Fotios Dimitriadis
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Darryl T. Martin
- Department of Urology; Yale University School of Medicine; New Haven, Connecticut
| | - Itaru Satoh
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Yukako Kinoshita
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
| | - Shuhei Tomita
- Division of Molecular Pharmacology; Tottori University School of Medicine; Yonago Japan
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Zhu R, Hu XQ, Xiao D, Yang S, Wilson SM, Longo LD, Zhang L. Chronic hypoxia inhibits pregnancy-induced upregulation of SKCa channel expression and function in uterine arteries. Hypertension 2013; 62:367-74. [PMID: 23716582 DOI: 10.1161/hypertensionaha.113.01236] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small-conductance Ca(2+)-activated K(+) (SKCa) channels are crucial in regulating vascular tone and blood pressure. The present study tested the hypothesis that SKCa channels play an important role in uterine vascular adaptation in pregnancy, which is inhibited by chronic hypoxia during gestation. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep maintained at sea level (≈300 m) or exposed to high-altitude (3801 m) hypoxia for 110 days. Immunohistochemistry revealed the presence of SKCa channels type 2 (SK2) and type 3 (SK3) in both smooth muscles and endothelium of uterine arteries. The expression of SK2 and SK3 channels was significantly increased during pregnancy, which was inhibited by chronic hypoxia. In normoxic animals, both SKCa channel opener NS309 and a large-conductance (BKCa) channel opener NS1619 relaxed norepinephrine-contracted uterine arteries in pregnant but not nonpregnant sheep. These relaxations were inhibited by selective SKCa and BKCa channel blockers, respectively. NS309-induced relaxation was largely endothelium-independent. In high-altitude hypoxic animals, neither NS1691 nor NS309 produced significant relaxation of uterine arteries in either nonpregnant or pregnant sheep. Similarly, the role of SKCa channels in regulating the myogenic reactivity of uterine arteries in pregnant animals was abrogated by chronic hypoxia. Accordingly, the enhanced SKCa channel activity in uterine arterial myocytes of pregnant animals was ablated by chronic hypoxia. The findings suggest a novel mechanism of SKCa channels in regulating myogenic adaptation of uterine arteries in pregnancy and in the maladaptation of uteroplacental circulation caused by chronic hypoxia during gestation.
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Affiliation(s)
- Ronghui Zhu
- Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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Sorensen CM, Braunstein TH, Holstein-Rathlou NH, Salomonsson M. Role of vascular potassium channels in the regulation of renal hemodynamics. Am J Physiol Renal Physiol 2012; 302:F505-18. [DOI: 10.1152/ajprenal.00052.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
K+ conductance is a major determinant of membrane potential ( Vm) in vascular smooth muscle (VSMC) and endothelial cells (EC). The vascular tone is controlled by Vm through the action of voltage-operated Ca2+ channels (VOCC) in VSMC. Increased K+ conductance leads to hyperpolarization and vasodilation, while inactivation of K+ channels causes depolarization and vasoconstriction. K+ channels in EC indirectly participate in the control of vascular tone by several mechanisms, e.g., release of nitric oxide and endothelium-derived hyperpolarizing factor. In the kidney, a change in the activity of one or more classes of K+ channels will lead to a change in hemodynamic resistance and therefore of renal blood flow and glomerular filtration pressure. Through these effects, the activity of renal vascular K+ channels influences renal salt and water excretion, fluid homeostasis, and ultimately blood pressure. Four main classes of K+ channels [calcium activated (KCa), inward rectifier (Kir), voltage activated (KV), and ATP sensitive (KATP)] are found in the renal vasculature. Several in vitro experiments have suggested a role for individual classes of K+ channels in the regulation of renal vascular function. Results from in vivo experiments are sparse. We discuss the role of the different classes of renal vascular K+ channels and their possible role in the integrated function of the renal microvasculature. Since several pathological conditions, among them hypertension, are associated with alterations in K+ channel function, the role of renal vascular K+ channels in the control of salt and water excretion deserves attention.
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Affiliation(s)
- Charlotte Mehlin Sorensen
- Institute of Biomedical Sciences, Division of Renal and Vascuar Physiology, The Panum Institute, and
| | - Thomas Hartig Braunstein
- Danish National Research Foundation Center for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | | | - Max Salomonsson
- Institute of Biomedical Sciences, Division of Renal and Vascuar Physiology, The Panum Institute, and
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