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Guo Y, Wang B, Gao H, Gao L, Hua R, Xu JD. ACE2 in the Gut: The Center of the 2019-nCoV Infected Pathology. Front Mol Biosci 2021; 8:708336. [PMID: 34631794 PMCID: PMC8493804 DOI: 10.3389/fmolb.2021.708336] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 08/11/2021] [Indexed: 12/25/2022] Open
Abstract
The 2019-nCoV is a rapidly contagious pneumonia caused by the recently discovered coronavirus. Although generally the most noticeable symptoms are concentrated in the lungs, the disorders in the gastrointestinal tract are of great importance in the diagnosis of 2019-nCoV. The angiotensin-converting enzyme 2 (ACE2), an important regulator of many physiological functions, including blood pressure and nutrients absorption, is recently identified as a vital entry for 2019-nCoV to enter host cells. In this review, we summarize its functions both physiologically and pathologically. We also elaborate its conflicting roles from the clews of contemporary researches, which may provide significant indications for pharmacological investigations and clinical uses.
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Affiliation(s)
- Yuexin Guo
- Department of Oral Medicine "5+3" Program, Basic Medical College, Capital Medical University, Beijing, China
| | - Boya Wang
- Undergraduate Student of 2018 Eight Program of Clinical Medicine, Peking University Health Science Center, Beijing, China
| | - Han Gao
- Department of Physiology and Pathophysiology, Basic Medical College, Capital Medical University, Beijing, China
| | - Lei Gao
- Department of Bioinformatics, School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Rongxuan Hua
- Department of Clinical Medicine "5+3" Program, Basic Medical College, Capital Medical University, Beijing, China
| | - Jing-Dong Xu
- Department of Physiology and Pathophysiology, Basic Medical College, Capital Medical University, Beijing, China
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2
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Kumar A, Priyamvada S, Soni V, Anbazhagan AN, Gujral T, Gill RK, Alrefai WA, Dudeja PK, Saksena S. Angiotensin II inhibits P-glycoprotein in intestinal epithelial cells. Acta Physiol (Oxf) 2020; 228:e13332. [PMID: 31177627 PMCID: PMC6899205 DOI: 10.1111/apha.13332] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 05/24/2019] [Accepted: 06/04/2019] [Indexed: 01/15/2023]
Abstract
AIM P-glycoprotein (Pgp/MDR1) plays a major role in intestinal homeostasis. Decrease in Pgp function and expression has been implicated in the pathogenesis of IBD. However, inhibitory mechanisms involved in the decrease of Pgp in inflammation are not fully understood. Angiotensin II (Ang II), a peptide hormone predominantly expressed in the epithelial cells of the crypt-villus junction of the intestine, has been shown to exert pro-inflammatory effects in the gut. It is increased in IBD patients and animals with experimental colitis. Whether Ang II directly influences Pgp is not known. METHODS Pgp activity was measured as verapamil-sensitive 3 H-digoxin flux. Pgp surface expression and exocytosis were measured by cell surface biotinylation studies. Signalling pathways were elucidated by Western blot analysis and pharmacological approaches. RESULTS Ang II (10 nM) significantly inhibited Pgp activity at 60 minutes. Ang II-mediated effects on Pgp function were receptor-mediated as the Ang II receptor 1 (ATR1) antagonist, losartan, blocked Pgp inhibition. Ang II effects on Pgp activity appeared to be mediated via PI3 kinase, p38 MAPK and Akt signalling. Ang II-mediated inhibition of Pgp activity was associated with a decrease in the surface membrane expression of Pgp protein via decreased exocytosis and was found to be dependent on the Akt pathway. Short-term treatment of Ang II (2 mg/kg b.wt., 2 hours) to mice also decreased the membrane expression of Pgp protein levels in ileum and colon. CONCLUSION Our findings provide novel insights into the role of Ang II and ATR1 in decreasing Pgp expression in intestinal inflammation.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Angiotensin II/administration & dosage
- Angiotensin II/pharmacology
- Animals
- Caco-2 Cells
- Dose-Response Relationship, Drug
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Gene Expression Regulation/drug effects
- Humans
- Intestinal Mucosa/cytology
- Mice
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/metabolism
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- p38 Mitogen-Activated Protein Kinases/genetics
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- Anoop Kumar
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Shubha Priyamvada
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Vikas Soni
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Arivarasu N. Anbazhagan
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Tarunmeet Gujral
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Ravinder K Gill
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Waddah A. Alrefai
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
| | - Pradeep K. Dudeja
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
| | - Seema Saksena
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
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3
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Casselbrant A, Malinauskas M, Marschall HU, Wallenius V, Fändriks L. Angiotensin II exerts dual actions on sodium-glucose transporter 1-mediated transport in the human jejunal mucosa. Scand J Gastroenterol 2016; 50:1068-75. [PMID: 25861809 DOI: 10.3109/00365521.2015.1019557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVES Intestinal glucose absorption is mainly mediated via the sodium-glucose transporter 1 (SGLT1) at the apex of the enterocytes, whereas the glucose transporter 2 (GLUT2) provides a basolateral exit. It has been shown in rats that Angiotensin II (AngII), the principal mediator of renin-angiotensin system (RAS), inhibits jejunal SGLT1-mediated glucose absorption. The aim of the present study was to investigate if a similar mechanism exists also in the human jejunal mucosa. MATERIAL AND METHODS Enteroscopy with mucosal biopsy sampling was performed in 28 healthy volunteers. Functional assessments were performed in Ussing chambers using a pharmacological approach. Western blotting and immunohistochemistry were used to assess the presence of the AngII type 1 (AT1R) and type 2 receptor (AT2R), as well as the glucose transporters SGLT1 and GLUT2. RESULTS Exposure of the mucosa to 10 mM glucose elicited a ≈50% increase in the epithelium-generated current (Iep). This glucose-induced electrogenic response was sensitive to the competitive SGLT1 inhibitor phlorizin, but not to AngII when given alone. AngII combined with the AT2R blocker PD123319 markedly inhibited the response. AngII in combination with the AT1R antagonist losartan tended to increase the electrogenic response, whereas direct activation of AT2R using the agonist C21 significantly enhanced the mucosal response to glucose. The AT1R and AT2R as well as SGLT1 and GLUT2 were detected inside the human enterocytes. CONCLUSIONS The pharmacological analysis indicated that activation of AT1R inhibits, whereas activation of AT2R enhances SGLT1-mediated glucose transport in the human jejunal mucosa.
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Affiliation(s)
- Anna Casselbrant
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden
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4
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Malinauskas M, Wallenius V, Fändriks L, Casselbrant A. Local expression of AP/AngIV/IRAP and effect of AngIV on glucose-induced epithelial transport in human jejunal mucosa. J Renin Angiotensin Aldosterone Syst 2015; 16:1101-8. [PMID: 26311161 DOI: 10.1177/1470320315599514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 07/12/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Recently it was shown that the classic renin-angiotensin system (RAS) is locally expressed in small intestinal enterocytes and exerts autocrine control of glucose transport. The aim of this study was to investigate if key components for the Angiotensin III (AngIII) and IV (AngIV) formation enzymes and the AngIV receptor, insulin-regulated aminopeptidase (IRAP), are present in the healthy jejunal mucosa. A second aim was to investigate AngIV effects on glucose-induced mucosal transport in vitro. MATERIAL AND METHODS Enteroscopy with mucosal biopsy sampling was performed in healthy volunteers. ELISA, Western blotting and immunohistochemistry were used to assess the protein levels and localization. The functional effect of AngIV was examined in Ussing chambers. RESULTS The substrate Angiotensin II, the enzymes aminopeptidases-A, B, M as well as IRAP were detected in the jejunal mucosa. Immunohistochemistry localized the enzymes to the apical brush-border membrane whereas IRAP was localized in the subapical cytosolic compartment in the enterocyte. AngIV increased the glucose-induced electrogenic transport in vitro. CONCLUSION The present study indicates the presence of substrates and enzymes necessary for AngIV formation as well as the receptor IRAP in the jejunal mucosa. The functional data suggest that AngIV regulates glucose uptake in the healthy human small intestine.
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Affiliation(s)
- M Malinauskas
- Institute of Physiology and Pharmacology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - V Wallenius
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - L Fändriks
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - A Casselbrant
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
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5
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Casselbrant A, Kostic S, Lönroth H. The muscular expression of RAS in patients with achalasia. J Renin Angiotensin Aldosterone Syst 2014; 16:578-86. [PMID: 24468662 DOI: 10.1177/1470320313498294] [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: 02/04/2013] [Accepted: 02/28/2013] [Indexed: 12/18/2022] Open
Abstract
INTRODUCTION Angiotensin II (AngII) elicits smooth muscle contractions via activation of AngII type 1 receptor (AT1R) in the intestinal wall and in sphincter regions in several species. Achalasia is a rare swallowing disorder and is characterized by a loss of the wave-like contraction that forces food through the oesophagus and a failure of the lower oesophageal sphincter to relax during swallowing. AIMS AND METHODS The present study was undertaken to elucidate expression and distribution of a local renin-angiotensin system (RAS) in the muscular layer of distal normal human oesophagus as well as in patients with achalasia using western blot analysis, immunohistochemistry and polymerase chain reaction (PCR). RESULTS AT1R, together with enzyme renin and cathepsin D expression were decreased in patients with achalasia. In contrast, the mast cells chymase, cathepsin G, neprilysin and the receptor for angiotensin 1-7 peptides, the MAS receptor, were increased in patients with achalasia. CONCLUSION The results showed the existence of a local RAS in human oesophageal muscular layer. The enzymes responsible for AngII production are different and there has been a shift in receptor physiology from AT1R to MAS receptor in patients with achalasia. These changes in the RAS might play a significant role in the physiological motor control for patients with achalasia.
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Affiliation(s)
- A Casselbrant
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - S Kostic
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - H Lönroth
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
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6
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Abstract
The gastrointestinal (GI) tract is fundamental for the intake of fluid and electrolytes and accommodates a large proportion of bodily hemodynamics and host defence systems. Despite that the renin-angiotensin system (RAS) is a prominent regulatory system for fluid and electrolyte homeostasis its impact on GI physiology is only little explored. Recent data indicate that RAS is well expressed and active in the GI tract although exact physiological roles are to be settled. There are several reports showing influences by RAS and its key mediator angiotensin II (AngII) on intestinal epithelial fluid and electrolyte transport and data are accumulating, suggesting involvement in GI mucosal inflammation and carcinogenesis. Of particular interest is the increasing amount of experimental support for the involvement of AngII formation and actions via the AngII subtype 1 (AT1) receptor in the pathogenesis and treatment of inflammatory bowel disease. The picture of RAS in the GI tract is, however, far from complete. Because RAS is an important application area for reno-cardiovascular diseases, a number of pharmacological agents as well as research technologies already exist and can in the future be used for GI research. A marked expansion of knowledge concerning the role of RAS in GI physiology and pathophysiology is to be expected.
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Affiliation(s)
- L Fändriks
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, University of Gothenburg, Sweden.
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7
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The angiotensin II type 2 receptor and the gastrointestinal tract. J Renin Angiotensin Aldosterone Syst 2009; 11:43-8. [DOI: 10.1177/1470320309347788] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The renin-angiotensin system (RAS) is well known for its vital involvement in body fluid homeostasis and circulation. However, very little research has been devoted to the impact of this regulatory system on the gastrointestinal (GI) system. This is surprising because the GI tract is fundamental for the intake and excretion of fluid and electrolytes (and nutrients), and it accommodates a large proportion of bodily haemodynamics and host defence systems. The RAS is well expressed and active in the GI tract, although the exact roles for the key mediator angiotensin II (Ang II) and its receptors in general, and the type 2 (AT 2) receptor in particular, are not completely settled. There are several reports showing Ang II regulation of intestinal fluid and electrolyte transport. For example, mucosaprotective duodenal bicarbonate-rich secretion is inhibited by Ang II via type 1 (AT1) receptor-mediated facilitation of sympathoadrenergic activity, but this secretory process can also be stimulated by Ang II via AT2 receptors. Novel data from human oesophagus and jejunum suggest that the AT1 receptor mediates muscular contractions and that the AT2 receptor regulates epithelial functions. Data are accumulating suggesting involvement of AT1 and AT2 receptors in GI inflammation and carcinogenesis. The picture of the RAS and AT 2 receptor in the GI tract is, however, far from complete. Much more basic research is needed with regard to GI pathophysiology before concluding clinical significance and potential applicability of pharmacological interferences with the RAS.
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8
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Musch MW, Li YC, Chang EB. Angiotensin II directly regulates intestinal epithelial NHE3 in Caco2BBE cells. BMC PHYSIOLOGY 2009; 9:5. [PMID: 19338654 PMCID: PMC2669048 DOI: 10.1186/1472-6793-9-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 04/01/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Angiotensin II (AII) effects on intestinal Na+ transport may be multifactorial. To determine if AII might have a direct effect on intestinal epithelial Na+ transport, we investigated its actions on Na+ transport in human intestinal epithelial Caco2BBE cells. RESULTS AII increased apical (brush border) sodium-hydrogen exchanger (NHE)-3, but not NHE2, activity within one hour. Similarly, only apical membrane NHE3 abundance increased at 1-2 hours without any change in total NHE3 protein abundance. From 4-48 hours, AII stimulated progressively larger increases in apical NHE3 activity and surface abundance, which was associated with increases in NHE3 protein expression. At 4-24 hours, NHE3 mRNA increases over baseline expression, suggesting increased gene transcription. This was supported by AII induced increases in rat NHE3 gene promoter-reporter activity. AII induction of NHE3 was blocked by the AII type I receptor antagonist losartan. Acute changes in AII-induced increases in NHE3 exocytosis were blocked by a phospholipase C inhibitor, an arachidonic acid cytochrome P450 epoxygenase inhibitor, as well as phosphatidylinositol 3 kinase (PI3K) inhibitors and Akt inhibitor, partially blocked by a metalloproteinase inhibitor and an EGF (epidermal growth factor) receptor kinase inhibitor, but not affected by an inhibitor of MEK-1 (MAPKK-1, mitogen activated protein kinase kinase-1). CONCLUSION We conclude that angiotensin II has a direct role in regulating intestinal fluid and electrolyte absorption which may contribute to its overall effects in regulation systemic volume and blood pressure. AII activates several key signaling pathways that induce acute and chronic changes in NHE3 membrane trafficking and gene transcription.
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Affiliation(s)
- Mark W Musch
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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9
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Tani T, Ayuzawa R, Takagi T, Kanehira T, Maurya DK, Tamura M. Angiotensin II bi-directionally regulates cyclooxygenase-2 expression in intestinal epithelial cells. Mol Cell Biochem 2008; 315:185-93. [PMID: 18543083 DOI: 10.1007/s11010-008-9806-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Accepted: 05/23/2008] [Indexed: 12/19/2022]
Abstract
We previously demonstrated that angiotensin II (Ang II) receptor signaling is involved in azoxymethane-induced mouse colon tumorigenesis. In order to clarify the role of Ang II in COX-2 expression in the intestinal epithelium, the receptor subtype-specific effect on COX-2 expression in a rat intestinal epithelial cell line (RIE-1) has been investigated. Ang II dose- and time-dependently increased the expression of COX-2, but not COX-1 mRNA and protein. This stimulation was completely blocked by the AT(1) receptor antagonist but not the AT(2) receptor antagonist. Ang II and lipopolysaccharide (LPS) additively induced COX-2 protein in RIE-1 cells, whereas the LPS-induced COX-2 expression was significantly attenuated by low concentrations of Ang II or the AT(2) agonistic peptide CGP-42112A only in AT(2) over-expressed cells. These data indicate that Ang II bi-directionally regulates COX-2 expression via both AT(1) and AT(2) receptors. Control of COX-2 expression through Ang II signaling may have significance in cytokine-induced COX-2 induction and colon tumorigenesis.
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Affiliation(s)
- Tatsuo Tani
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA
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10
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Spak E, Casselbrant A, Olbers T, Lönroth H, Fändriks L. Angiotensin II-induced contractions in human jejunal wall musculature in vitro. Acta Physiol (Oxf) 2008; 193:181-90. [PMID: 18081740 DOI: 10.1111/j.1748-1716.2007.01826.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
AIM Angiotensin II is well known for its contractile effects on smooth muscle cells. This effect is also present in the gut previously shown in animal models. The aim of this study was to clarify expression and localization of angiotensin II receptors in the human small intestine and to explore the pharmacological profile of angiotensin II effects in vitro. METHODS Strips of jejunal muscle wall from 32 patients undergoing bariatric surgery were used to record isometric tension in vitro in response to angiotensin II (10(-10)-10(-5) M) alone and in the presence of PD123319 (10(-7) M), losartan (10(-7) M), PD123319 (10(-7) M) and losartan (10(-7) M) in combination, tetrodotoxin (TTX) (10(-6) M), atropine (10(-6) M) and guanethidine (3 x 10(-6) M). Western blot, immunohistochemistry and RT-PCR were performed on corresponding muscle samples to identify expression and localization of key components of the renin-angiotensin system. RESULTS Angiotensin II elicited concentration-dependent contraction in both longitudinal and circular jejunal muscle wall strips; neither TTX, atropine nor guanethidine affected this action. Losartan alone and in combination with PD123319 shifted the concentration-response curve to the right. Transcription of angiotensinogen, ACE and angiotensin II types 1 and 2 receptor RNA was detected in all patients. Immunohistochemistry detected angiotensin II type 1 receptors in the musculature; both angiotensin II types 1 and type 2 receptors were found in the myenteric plexus. CONCLUSION This pharmacological analysis indicates that the contractile action elicited by angiotensin II on jejunal wall musculature is primarily mediated through the angiotensin II type 1 receptor located on the musculature.
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MESH Headings
- Adult
- Aged
- Angiotensin II/pharmacology
- Blotting, Western
- Dose-Response Relationship, Drug
- Humans
- Jejunum/drug effects
- Jejunum/metabolism
- Jejunum/physiology
- Middle Aged
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Muscle, Smooth/physiology
- RNA, Messenger/genetics
- Receptor, Angiotensin, Type 1/biosynthesis
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 2/biosynthesis
- Receptor, Angiotensin, Type 2/genetics
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Tissue Culture Techniques
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Affiliation(s)
- E Spak
- Department of Gastrosurgical Research, Sahlgrenska Academy, University of Gothenburg, Sweden.
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11
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Casselbrant A, Edebo A, Wennerblom J, Lönroth H, Helander HF, Vieth M, Lundell L, Fändriks L. Actions by angiotensin II on esophageal contractility in humans. Gastroenterology 2007; 132:249-60. [PMID: 17241875 DOI: 10.1053/j.gastro.2006.11.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 10/12/2006] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Angiotensin II is a potent activator of smooth muscles but has not been much investigated with regard to gastrointestinal motor activity. This study explores expression of the renin-angiotensin system (RAS) in human esophageal musculature and actions by Angiotensin II both in vitro and in vivo. METHODS Muscular specimens of esophageal body and lower esophageal sphincter were obtained from patients undergoing resection as a result of mucosal neoplasm. Healthy volunteers participated in functional examinations of esophageal motility assessed by high-resolution manometry and multiple transmucosal potential-difference measurements. RESULTS Gene transcripts of key components of RAS were found in the esophageal musculature. Immunohistochemistry revealed a distinct staining for Angiotensin II type 1 (AT(1)) receptors in the muscular bundles and blood-vessel walls, whereas Angiotensin II type 2 receptors were confined to blood vessels only. Angiotensin II caused concentration-dependent contractions in vitro, which were inhibited by the AT(1) receptor antagonist losartan but not by the Angiotensin II type 2 receptor antagonist PD123319. Administration of the AT(1) receptor antagonist candesartan reduced the amplitude of swallow-induced peristaltic contractions and both the length and pressure amplitude of baseline high-pressure zone at the esophagogastric junction. Neither swallow-induced axial movements, nor the contraction after transient lower esophageal sphincter relaxations, were influenced by candesartan pretreatment. CONCLUSIONS The study demonstrates a local RAS in the musculature of the distal esophagus and that Angiotensin II is a potent stimulator of esophageal contractions via the AT(1) receptor. The results suggest that Angiotensin II participates in the physiological control of the human esophageal motor activity.
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MESH Headings
- Aged
- Aged, 80 and over
- Angiotensin II/pharmacology
- Angiotensin II Type 1 Receptor Blockers/administration & dosage
- Angiotensinogen/genetics
- Benzimidazoles/administration & dosage
- Biphenyl Compounds
- Esophageal Sphincter, Lower/physiology
- Esophagus/physiology
- Female
- Gene Expression
- Humans
- In Vitro Techniques
- Male
- Manometry
- Middle Aged
- Muscle Contraction/drug effects
- Peptidyl-Dipeptidase A/genetics
- Peristalsis/drug effects
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Renin/genetics
- Renin/metabolism
- Tetrazoles/administration & dosage
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Anna Casselbrant
- Department of Gastrosurgical Research, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
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12
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Ewert S, Spak E, Olbers T, Johnsson E, Edebo A, Fändriks L. Angiotensin II induced contraction of rat and human small intestinal wall musculature in vitro. Acta Physiol (Oxf) 2006; 188:33-40. [PMID: 16911251 DOI: 10.1111/j.1748-1716.2006.01600.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Angiotensin II (Ang II) is a well-known activator of smooth muscle in the vasculature but has been little explored with regard to intestinal wall muscular activity. This study investigates pharmacological properties of Ang II and expression of its receptors in small-intestinal smooth muscle from rats and humans. METHODS Isometric recordings were performed in vitro on small intestinal longitudinal muscle strips. Protein expressions of Ang II typ 1 (AT1R) and typ 2 (AT2R) receptors were assessed by Western blot. RESULTS Ang II elicited concentration-dependent contractions of rat jejunal and ileal muscle preparations. The concentration-response curve (rat ileum, EC(50): 1.5 +/- 0.9 x 10(-8) M) was shifted to the right by the AT1R receptor antagonist losartan (10(-7) M) but was unaffected by the AT2R antagonist PD123319 (10(-7) M) as well as by the adrenolytic guanethidine (3 x 10(-6) M) and the anticholinergic atropine (10(-6) M). Human duodenal, jejunal and ileal longitudinal muscle preparations all contracted concentration-dependently in response to Ang II. The concentration-response curve (human jejunum, EC(50): 1.5 +/- 0.8 x 10(-8) M) was shifted to the right by losartan (10(-7) M) but was unaffected by PD123319 (10(-7) M). Both AT1R and AT2R were detected in all segments of the rat small intestinal wall musculature, whereas only AT1R was readily detectable in the human samples. CONCLUSION Ang II elicits contractions of small-intestinal longitudinal muscle preparations from the small intestine of rats and man. The pharmacological pattern and protein expression analyses indicate mediation via the AT1R.
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MESH Headings
- Adrenergic Antagonists/pharmacology
- Adult
- Aged
- Angiotensin II/pharmacology
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Angiotensin II Type 2 Receptor Blockers
- Animals
- Atropine/pharmacology
- Blotting, Western/methods
- Cholinergic Antagonists/pharmacology
- Dose-Response Relationship, Drug
- Female
- Guanethidine/pharmacology
- Humans
- Imidazoles/pharmacology
- In Vitro Techniques
- Intestine, Small/drug effects
- Intestine, Small/physiology
- Losartan/pharmacology
- Male
- Middle Aged
- Muscle Contraction/drug effects
- Muscle, Smooth/chemistry
- Muscle, Smooth/drug effects
- Muscle, Smooth/physiology
- Pyridines/pharmacology
- Rats
- Receptor, Angiotensin, Type 1/analysis
- Receptor, Angiotensin, Type 2/analysis
- Species Specificity
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Affiliation(s)
- S Ewert
- Department of Gastrosurgical Research, Institute of Clinical Sciences, Sahlgrenska Academy, Goteborg University, Gothenburg, Sweden
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