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Choi J, Cayabyab F, Perez H, Yoshihara E. Scaling Insulin-Producing Cells by Multiple Strategies. Endocrinol Metab (Seoul) 2024:EnM.2023.1910. [PMID: 38572534 DOI: 10.3803/enm.2023.1910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 01/30/2024] [Indexed: 04/05/2024] Open
Abstract
In the quest to combat insulin-dependent diabetes mellitus (IDDM), allogenic pancreatic islet cell therapy sourced from deceased donors represents a significant therapeutic advance. However, the applicability of this approach is hampered by donor scarcity and the demand for sustained immunosuppression. Human induced pluripotent stem cells are a game-changing resource for generating synthetic functional insulin-producing β cells. In addition, novel methodologies allow the direct expansion of pancreatic progenitors and mature β cells, thereby circumventing prolonged differentiation. Nevertheless, achieving practical reproducibility and scalability presents a substantial challenge for this technology. As these innovative approaches become more prominent, it is crucial to thoroughly evaluate existing expansion techniques with an emphasis on their optimization and scalability. This manuscript delineates these cutting-edge advancements, offers a critical analysis of the prevailing strategies, and underscores pivotal challenges, including cost-efficiency and logistical issues. Our insights provide a roadmap, elucidating both the promises and the imperatives in harnessing the potential of these cellular therapies for IDDM.
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Affiliation(s)
- Jinhyuk Choi
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Fritz Cayabyab
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Harvey Perez
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Eiji Yoshihara
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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Fu T, Huan T, Rahman G, Zhi H, Xu Z, Oh TG, Guo J, Coulter S, Tripathi A, Martino C, McCarville JL, Zhu Q, Cayabyab F, Low B, He M, Xing S, Vargas F, Yu RT, Atkins A, Liddle C, Ayres J, Raffatellu M, Dorrestein PC, Downes M, Knight R, Evans RM. Paired microbiome and metabolome analyses associate bile acid changes with colorectal cancer progression. Cell Rep 2023; 42:112997. [PMID: 37611587 PMCID: PMC10903535 DOI: 10.1016/j.celrep.2023.112997] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 05/08/2023] [Accepted: 08/01/2023] [Indexed: 08/25/2023] Open
Abstract
Colorectal cancer (CRC) is driven by genomic alterations in concert with dietary influences, with the gut microbiome implicated as an effector in disease development and progression. While meta-analyses have provided mechanistic insight into patients with CRC, study heterogeneity has limited causal associations. Using multi-omics studies on genetically controlled cohorts of mice, we identify diet as the major driver of microbial and metabolomic differences, with reductions in α diversity and widespread changes in cecal metabolites seen in high-fat diet (HFD)-fed mice. In addition, non-classic amino acid conjugation of the bile acid cholic acid (AA-CA) increased with HFD. We show that AA-CAs impact intestinal stem cell growth and demonstrate that Ileibacterium valens and Ruminococcus gnavus are able to synthesize these AA-CAs. This multi-omics dataset implicates diet-induced shifts in the microbiome and the metabolome in disease progression and has potential utility in future diagnostic and therapeutic developments.
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Affiliation(s)
- Ting Fu
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Tao Huan
- Department of Chemistry, UBC Faculty of Science, Vancouver Campus, Vancouver, BC V6T 1Z4, Canada
| | - Gibraan Rahman
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Hui Zhi
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zhenjiang Xu
- UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Tae Gyu Oh
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jian Guo
- Department of Chemistry, UBC Faculty of Science, Vancouver Campus, Vancouver, BC V6T 1Z4, Canada
| | - Sally Coulter
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead, NSW 2145, Australia
| | - Anupriya Tripathi
- UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Cameron Martino
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Justin L McCarville
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Qiyun Zhu
- UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fritz Cayabyab
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Brian Low
- Department of Chemistry, UBC Faculty of Science, Vancouver Campus, Vancouver, BC V6T 1Z4, Canada
| | - Mingxiao He
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Shipei Xing
- Department of Chemistry, UBC Faculty of Science, Vancouver Campus, Vancouver, BC V6T 1Z4, Canada
| | - Fernando Vargas
- UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ruth T Yu
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Annette Atkins
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Christopher Liddle
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead, NSW 2145, Australia
| | - Janelle Ayres
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Manuela Raffatellu
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA; Chiba University-UC San Diego Center for Mucosal Immunity, Allergy, and Vaccines (CU-UCSD cMAV), La Jolla, CA 92093, USA
| | - Pieter C Dorrestein
- UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA; Department of Engineering, University of California, San Diego, La Jolla, CA 92093, USA; Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael Downes
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Rob Knight
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA; Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; UCSD Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA; Department of Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Ronald M Evans
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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Choi J, Cayabyab F, Yoshihara E. A guide from the stomach to β cells. Nat Cell Biol 2023; 25:637-638. [PMID: 37106061 DOI: 10.1038/s41556-023-01140-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Jinhyuk Choi
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Fritz Cayabyab
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Eiji Yoshihara
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, CA, USA.
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.
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Yoshihara E, O'Connor C, Gasser E, Wei Z, Oh TG, Tseng TW, Wang D, Cayabyab F, Dai Y, Yu RT, Liddle C, Atkins AR, Downes M, Evans RM. Publisher Correction: Immune-evasive human islet-like organoids ameliorate diabetes. Nature 2021; 590:E27. [PMID: 33469222 DOI: 10.1038/s41586-020-03109-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Eiji Yoshihara
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.,The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, CA, USA.,David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Carolyn O'Connor
- Flow Cytometry Core Facility, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Emanuel Gasser
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Zong Wei
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Scottsdale, AZ, USA
| | - Tae Gyu Oh
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tiffany W Tseng
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Dan Wang
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Fritz Cayabyab
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Yang Dai
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ruth T Yu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Christopher Liddle
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead, New South Wales, Australia
| | - Annette R Atkins
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Michael Downes
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ronald M Evans
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA. .,Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA.
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Abstract
Diabetes is a complex disease that affects over 400 million people worldwide. The life-long insulin injections and continuous blood glucose monitoring required in type 1 diabetes (T1D) represent a tremendous clinical and economic burdens that urges the need for a medical solution. Pancreatic islet transplantation holds great promise in the treatment of T1D; however, the difficulty in regulating post-transplantation immune reactions to avoid both allogenic and autoimmune graft rejection represent a bottleneck in the field of islet transplantation. Cell replacement strategies have been performed in hepatic, intramuscular, omentum, and subcutaneous sites, and have been performed in both animal models and human patients. However more optimal transplantation sites and methods of improving islet graft survival are needed to successfully translate these studies to a clinical relevant therapy. In this review, we summarize the current progress in the field as well as methods and sites of islet transplantation, including stem cell-derived functional human islets. We also discuss the contribution of immune cells, vessel formation, extracellular matrix, and nutritional supply on islet graft survival. Developing new transplantation sites with emerging technologies to improve islet graft survival and simplify immune regulation will greatly benefit the future success of islet cell therapy in the treatment of diabetes.
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Affiliation(s)
- Fritz Cayabyab
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Lina R. Nih
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
- David Geffen School of Medicine at University of California, Los Angeles, CA, United States
| | - Eiji Yoshihara
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
- David Geffen School of Medicine at University of California, Los Angeles, CA, United States
- *Correspondence: Eiji Yoshihara,
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Yoshihara E, O'Connor C, Gasser E, Wei Z, Oh TG, Tseng TW, Wang D, Cayabyab F, Dai Y, Yu RT, Liddle C, Atkins AR, Downes M, Evans RM. Immune-evasive human islet-like organoids ameliorate diabetes. Nature 2020; 586:606-611. [PMID: 32814902 PMCID: PMC7872080 DOI: 10.1038/s41586-020-2631-z] [Citation(s) in RCA: 161] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 05/18/2020] [Indexed: 01/06/2023]
Abstract
While stem cell-derived islets hold promise as a therapy for insulin-dependent diabetes, challenges remain in achieving this goal1–6. Here we generate human islet-like organoids (HILOs) from induced pluripotent stem cells (iPSCs) and show that non-canonical WNT4 signaling drives the metabolic maturation necessary for robust ex vivo glucose-stimulated insulin secretion. These functionally mature HILOs contain endocrine-like cell types that, upon transplantation, rapidly re-establish glucose homeostasis in diabetic NOD-SCID mice. Overexpression of the immune checkpoint protein PD-L1 protected HILO xenografts such that they were able to restore glucose homeostasis in immune-competent diabetic mice for 50 days. Furthermore, ex vivo interferon gamma stimulation induced endogenous PD-L1 expression and restricted T cell activation and graft rejection. The generation of glucose-responsive islet-like organoids able to avoid immune detection provides a promising alternative to cadaveric and device-dependent therapies in the treatment of diabetes.
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Affiliation(s)
- Eiji Yoshihara
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.,The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, CA, USA.,David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Carolyn O'Connor
- Flow Cytometry Core Facility, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Emanuel Gasser
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Zong Wei
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Scottsdale, AZ, USA
| | - Tae Gyu Oh
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tiffany W Tseng
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Dan Wang
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Fritz Cayabyab
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Yang Dai
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ruth T Yu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Christopher Liddle
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead, New South Wales, Australia
| | - Annette R Atkins
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Michael Downes
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ronald M Evans
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA. .,Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA.
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Fu T, Coulter S, Yoshihara E, Oh TG, Fang S, Cayabyab F, Zhu Q, Zhang T, Leblanc M, Liu S, He M, Waizenegger W, Gasser E, Schnabl B, Atkins AR, Yu RT, Knight R, Liddle C, Downes M, Evans RM. FXR Regulates Intestinal Cancer Stem Cell Proliferation. Cell 2019; 176:1098-1112.e18. [PMID: 30794774 PMCID: PMC6701863 DOI: 10.1016/j.cell.2019.01.036] [Citation(s) in RCA: 257] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/28/2018] [Accepted: 01/23/2019] [Indexed: 02/06/2023]
Abstract
Increased levels of intestinal bile acids (BAs) are a risk factor for colorectal cancer (CRC). Here, we show that the convergence of dietary factors (high-fat diet) and dysregulated WNT signaling (APC mutation) alters BA profiles to drive malignant transformations in Lgr5-expressing (Lgr5+) cancer stem cells and promote an adenoma-to-adenocarcinoma progression. Mechanistically, we show that BAs that antagonize intestinal farnesoid X receptor (FXR) function, including tauro-β-muricholic acid (T-βMCA) and deoxycholic acid (DCA), induce proliferation and DNA damage in Lgr5+ cells. Conversely, selective activation of intestinal FXR can restrict abnormal Lgr5+ cell growth and curtail CRC progression. This unexpected role for FXR in coordinating intestinal self-renewal with BA levels implicates FXR as a potential therapeutic target for CRC.
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Affiliation(s)
- Ting Fu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sally Coulter
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead NSW 2145, Australia
| | - Eiji Yoshihara
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Tae Gyu Oh
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sungsoon Fang
- Severance Biomedical Science Institute, BK21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, South Korea
| | - Fritz Cayabyab
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Qiyun Zhu
- Department of Medicine, University of California San Diego, La Jolla, CA 92037, USA
| | - Tong Zhang
- Waitt Biophotonics Core, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mathias Leblanc
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sihao Liu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mingxiao He
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Wanda Waizenegger
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Emanuel Gasser
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Bernd Schnabl
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92037, USA
| | - Annette R Atkins
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Ruth T Yu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Rob Knight
- Department of Medicine, University of California San Diego, La Jolla, CA 92037, USA; Department of Computer Science and Engineering, University of California San Diego, La Jolla, CA 92037, USA
| | - Christopher Liddle
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney Medical School, University of Sydney, Westmead NSW 2145, Australia
| | - Michael Downes
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
| | - Ronald M Evans
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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Daniel EE, Jury J, Christinck F, Cayabyab F. Chloride-mediated inhibitory junction potentials in opossum esophageal circular smooth muscle. Am J Physiol 1992; 263:G135-8. [PMID: 1636710 DOI: 10.1152/ajpgi.1992.263.1.g135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Christinck F, Jury J, Cayabyab F, Daniel EE. Nitric oxide may be the final mediator of nonadrenergic, noncholinergic inhibitory junction potentials in the gut. Can J Physiol Pharmacol 1991; 69:1448-58. [PMID: 1777844 DOI: 10.1139/y91-217] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This study tested the hypothesis that the final mediator of nonadrenergic, noncholinergic (NANC) inhibitory junction potentials (ijps) and associated relaxation responses was nitric oxide (NO) or a related substance and not vasoactive intestinal polypeptide (VIP). We used opossum esophagus body circular muscle and canine intestine circular muscle. In both these tissues, ijps had reversal potentials near the potassium equilibrium potential, (EK); in esophagus the ijps were apamin insensitive, but in the intestine they were partially apamin sensitive. N omega-Nitro-L-arginine methyl ester (NAME) (10(-5) to 5 x 10(-4) M) abolished ijps in both tissues, an effect overcome by 10(-3) M L-arginine but not D-arginine. NAME increased input resistance of esophagus tissues in the double sucrose gap but caused no significant depolarization in the sucrose gap or in studies with microelectrodes. Contractions and basal tension were increased in both tissues by NAME. The apamin sensitive and insensitive ijp components in canine muscle were both abolished by NAME, but the time course of this abolition was different for the two components. Methylene blue (10-50 microM) with variable rapidity and extent inhibited ijps in both tissues, but L-arginine could not overcome this effect. Methylene blue, like NAME, did not depolarize detectably but enhanced the contractile activity. VIP (10(-6) M) had very small effects in both tissues, little or no hyperpolarization and increased input resistance in esophagus, these effects were not changed by NAME, and VIP did not affect ijps. We conclude that NO may be the final mediator of NANC-initiated inhibitory junction potentials in gastrointestinal circular smooth muscle.
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Affiliation(s)
- F Christinck
- McMaster University, Department of Biomedical Sciences, Hamilton, Ont., Canada
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