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Tompkins E, Mimic B, Penn RB, Pera T. The biased M3 mAChR ligand PD 102807 mediates qualitatively distinct signaling to regulate airway smooth muscle phenotype. J Biol Chem 2023; 299:105209. [PMID: 37660916 PMCID: PMC10520882 DOI: 10.1016/j.jbc.2023.105209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 08/14/2023] [Accepted: 08/22/2023] [Indexed: 09/05/2023] Open
Abstract
Airway smooth muscle (ASM) cells attain a hypercontractile phenotype during obstructive airway diseases. We recently identified a biased M3 muscarinic acetylcholine receptor (mAChR) ligand, PD 102807, that induces GRK-/arrestin-dependent AMP-activated protein kinase (AMPK) activation to inhibit transforming growth factor-β-induced hypercontractile ASM phenotype. Conversely, the balanced mAChR agonist, methacholine (MCh), activates AMPK yet does not regulate ASM phenotype. In the current study, we demonstrate that PD 102807- and MCh-induced AMPK activation both depend on Ca2+/calmodulin-dependent kinase kinases (CaMKKs). However, MCh-induced AMPK activation is calcium-dependent and mediated by CaMKK1 and CaMKK2 isoforms. In contrast, PD 102807-induced signaling is calcium-independent and mediated by the atypical subtype protein kinase C-iota and the CaMKK1 (but not CaMKK2) isoform. Both MCh- and PD 102807-induced AMPK activation involve the AMPK α1 isoform. PD 102807-induced AMPK α1 (but not AMPK α2) isoform activation mediates inhibition of the mammalian target of rapamycin complex 1 (mTORC1) in ASM cells, as demonstrated by increased Raptor (regulatory-associated protein of mTOR) phosphorylation as well as inhibition of phospho-S6 protein and serum response element-luciferase activity. The mTORC1 inhibitor rapamycin and the AMPK activator metformin both mimic the ability of PD 102807 to attenuate transforming growth factor-β-induced α-smooth muscle actin expression (a marker of hypercontractile ASM). These data indicate that PD 102807 transduces a signaling pathway (AMPK-mediated mTORC1 inhibition) qualitatively distinct from canonical M3 mAChR signaling to prevent pathogenic remodeling of ASM, thus demonstrating PD 102807 is a biased M3 mAChR ligand with therapeutic potential for the management of obstructive airway disease.
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Affiliation(s)
- Eric Tompkins
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Bogdana Mimic
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Raymond B Penn
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Tonio Pera
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA.
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7,8-Dihydroxyflavone Enhanced Colonic Cholinergic Contraction and Relieved Loperamide-Induced Constipation in Rats. Dig Dis Sci 2021; 66:4251-4262. [PMID: 33528684 DOI: 10.1007/s10620-020-06817-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 12/29/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Whether 7,8-dihydroxyflavone (7,8-DHF), a tyrosine kinase receptor B (TrkB) agonist, modulates colonic smooth muscle motility and/or alleviates constipation has not yet been studied. AIMS Here, we aimed to determine how 7,8-DHF influences carbachol (CCh)-stimulated contraction of colonic strips and the in vivo effect of 7,8-DHF on constipation. METHODS Muscle strips were isolated from rat colons for recording contractile tension and performing western blotting. Constipation was induced in rats with loperamide. RESULTS Although it specifically activated TrkB, 7,8-DHF applied alone neither activated PLCγ1 in the colonic strips nor induced colonic strip contraction. However, 7,8-DHF enhanced CCh-stimulated PLCγ1 activation and strip contraction. The PLCγ1 antagonist U73122 suppressed both CCh-stimulated and 7,8-DHF-enhanced/CCh-stimulated contraction. While clarifying the underlying mechanism, we revealed that 7,8-DHF augmented muscarinic M3 receptor expression in the colonic strips. The M3-selective antagonist tarafenacin specifically inhibited the 7,8-DHF-enhanced/CCh-stimulated contraction of the colonic strips. Since 7,8-DHF increased Akt phosphorylation, and LY294002 (an antagonist of PI3K upstream of Akt) dramatically inhibited both 7,8-DHF-augmented M3 expression and 7,8-DHF-enhanced/CCh-stimulated contractions, we assumed that 7,8-DHF/TrkB/Akt was associated with the modulation of M3 expression in the colonic strips. ANA-12, a specific TrkB antagonist, not only inhibited TrkB activation by 7,8-DHF but also suppressed 7,8-DHF-enhanced cholinergic contraction, 7,8-DHF/CCh-mediated activation of PLCγ1/Akt, and M3 overexpression in colonic strips. In vivo 7,8-DHF, also by promoting intestinal motility and M3 expression, significantly alleviated loperamide-induced functional constipation in rats. CONCLUSIONS Our results suggest that 7,8-DHF regulates colonic motility possibly via a TrkB/Akt/M3 pathway and may be applicable for alleviating constipation.
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Singh K, Randhwa G, Salloum FN, Grider JR, Murthy KS. Decreased smooth muscle function, peristaltic activity, and gastrointestinal transit in dystrophic (mdx) mice. Neurogastroenterol Motil 2021; 33:e13968. [PMID: 32789934 DOI: 10.1111/nmo.13968] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/21/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD) is characterized by the lack of dystrophin in skeletal, cardiac, and smooth muscle. Slow colonic transit and constipation are common in DMD patients and animal models of DMD. However, the cause of this hypocontractility and the expression of contractile proteins in smooth muscle are unknown. The aim of the study was to investigate the expression of contractile proteins in the colonic smooth muscle and the function of the colon in control and mdx mice. METHODS Muscle contraction was measured in muscle strips and isolated muscle cells. Peristaltic activity was measured in ex vivo preparations by spatiotemporal mapping, and gastrointestinal (GI) transit in vivo was measured by the distribution of fluorescent marker along the intestine and colon. mRNA expression of contractile proteins smoothelin, caldesmon, calponin, and tropomyosin was measured by qRT-PCR. RESULTS Expression of mRNA for contractile proteins was decreased in colonic smooth muscle of mdx mice compared with control. Contraction in response to acetylcholine and KCl was decreased in colonic muscle strips and in isolated muscle cells of mdx mice. Distension of ex vivo colons with Krebs buffer induced peristalsis in both control and mdx mice; however, significantly fewer full peristaltic waves were recorded in the colons of mdx mice. GI transit was also inhibited in mdx mice. CONCLUSION AND INFERENCES The data indicate that the lack of dystrophin causes decrease in colonic smooth muscle contractility, peristalsis, and GI transit and provides the basis for analysis of mechanisms involved in smooth muscle dysfunction in DMD.
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Affiliation(s)
- Kulpreet Singh
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Gurpreet Randhwa
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Fadi N Salloum
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - John R Grider
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Karnam S Murthy
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
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Berndt‐Paetz M, Herbst L, Weimann A, Gonsior A, Stolzenburg J, Neuhaus J. IC/BPS‐associated alterations of M2 and M3 muscarinic acetylcholine receptor trafficking in human detrusor. Neurourol Urodyn 2019; 38:1818-1827. [DOI: 10.1002/nau.24087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/10/2019] [Indexed: 12/26/2022]
Affiliation(s)
- Mandy Berndt‐Paetz
- Department of Urology, Research LaboratoriesUniversity of Leipzig Leipzig Germany
| | - Luise Herbst
- Department of Urology, Research LaboratoriesUniversity of Leipzig Leipzig Germany
| | - Annett Weimann
- Department of Urology, Research LaboratoriesUniversity of Leipzig Leipzig Germany
| | - Andreas Gonsior
- Department of UrologyUniversity Hospital Leipzig AöR Leipzig Germany
| | | | - Jochen Neuhaus
- Department of Urology, Research LaboratoriesUniversity of Leipzig Leipzig Germany
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Mahavadi S, Grider JR, Murthy KS. Muscarinic m2 receptor-mediated actin polymerization via PI3 kinase γ and integrin-linked kinase in gastric smooth muscle. Neurogastroenterol Motil 2019; 31:e13495. [PMID: 30393912 PMCID: PMC6347515 DOI: 10.1111/nmo.13495] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/07/2018] [Accepted: 09/25/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Actin polymerization plays an important role in smooth muscle contraction. Integrin-linked kinase (ILK) was shown to mediate actin polymerization in airway smooth muscle. The role of ILK in actin polymerization in response to m2 receptor activation was not in gastric smooth muscle. METHODS Phosphorylation of paxillin, neuronal Wiskott-Aldrich syndrome protein (N-WASp), and association of paxillin with GEF proteins (Cool2/αPix [Cool2/PAK-interacting exchange factor alpha], Cool1/βPix [Cool1/PAK-interacting exchange factor beta], and DOCK 180 [Dedicator of cytokinesis]) and N-WASp with Arp2/3 complex were measured by western blot. Activation of Cdc42 was determined using an antibody for activated Cdc42. Actin polymerization was measured as an increase in F-actin/G-actin ratio. RESULTS Phosphorylation of paxillin, an association of paxillin with GEF proteins, Cdc42 activity, and actin polymerization were increased in response to m2 receptor activation in gastric smooth muscle cells. The increases in paxillin phosphorylation, Cdc42 activity, and actin polymerization were inhibited by a PI3Kγ inhibitor (AS-605240), ILK siRNA, and ILK dominant negative mutant (ILK [R211]). Increase in actin polymerization was also inhibited by Cdc42 dominant negative mutant (Cdc42 [T17N]). Increases in the association of paxillin with GEF proteins, phosphorylation of N-WASp and its association with Arp2/3 complex were inhibited by ILK (R211). CONCLUSION In gastric smooth muscle cells, activation of PI3Kγ by muscarinic m2 receptors causes ILK-dependent phosphorylation of paxillin, an association of paxillin with Cdc42 GEF proteins and activation of Cdc42, which, in turn, causes phosphorylation of N-WASp and its association with Arp2/3 complex leading to actin polymerization.
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Affiliation(s)
- Sunila Mahavadi
- Department of Physiology and Biophysics VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond Virginia
| | - John R. Grider
- Department of Physiology and Biophysics VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond Virginia
| | - Karnam S. Murthy
- Department of Physiology and Biophysics VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond Virginia
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He B, Qu Z, Tian Z, Zhao K, Wei L, Ma L. 7,8-dihydroxyflavone enhanced cholinergic contraction of rat gastric smooth muscle via augmenting muscarinic M3 receptor expression. Clin Exp Pharmacol Physiol 2018; 45:1170-1180. [PMID: 29927500 DOI: 10.1111/1440-1681.12999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Baoguo He
- Department of Gastroenterology, Affiliated Hospital; Qingdao University; Qingdao China
| | - Zhiqiang Qu
- Center for Medical Research, Affiliated Hospital; Qingdao University; Qingdao China
| | - Zibin Tian
- Department of Gastroenterology, Affiliated Hospital; Qingdao University; Qingdao China
| | - Kun Zhao
- Department of Gastroenterology, Affiliated Hospital; Qingdao University; Qingdao China
| | - Liangzhou Wei
- Department of Gastroenterology, Affiliated Hospital; Qingdao University; Qingdao China
| | - Li Ma
- Department of Clinical Nutrition, Affiliated Hospital; Qingdao University; Qingdao China
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Ferreira CHF, Shifrin Y, Pan J, Ivanovska J, McNamara PJ, Belik J. The newborn rat gastric emptying rate is volume and not developmentally dependent. Neurogastroenterol Motil 2018; 30:e13233. [PMID: 29024213 DOI: 10.1111/nmo.13233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/19/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Gastric residuals are a common finding in enterally fed preterm neonates and traditionally thought to reflect immaturity-related delayed gastric emptying. Adult human data suggest that the meal volume regulate the gastric emptying rate, but early in life, this has not been adequately evaluated. The goal of this study was to study the rat postnatal changes in gastric emptying rate and the strain-induced effect on muscle contraction. We hypothesized that the stomach content volume and not developmental factors determines the newborn gastric emptying rate, via the Rho-kinase 2 (ROCK-2) pathway. METHODS Gastric volume and emptying rate measurements were obtained by ultrasound at different postprandial times and the wall strain-dependent changes in muscle contraction were evaluated ex vivo. KEY RESULTS The newborn rat gastric emptying rate was unrelated to postnatal age, maximal 30 min postprandial, and directly proportional to content volume. In vitro measurements showed that the agonist-induced gastric muscle contraction was directly proportional to the stomach wall strain. These changes were mediated via upregulation of ROCK-2 activity. CONCLUSIONS & INFERENCES The newborn rat gastric emptying rate is not developmentally regulated, but dependent on the content volume via wall strain-induced ROCK-2 activation. Further clinical studies addressing the content volume effect on the rate of gastric emptying are warranted, to enhance feeding tolerance in preterm neonates.
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Affiliation(s)
- C H F Ferreira
- Hospital das Clinicas, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Y Shifrin
- Departments of Paediatrics and Physiology, Translational Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON, Canada
| | - J Pan
- Departments of Paediatrics and Physiology, Translational Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON, Canada
| | - J Ivanovska
- Departments of Paediatrics and Physiology, Translational Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON, Canada
| | - P J McNamara
- Departments of Paediatrics and Physiology, Translational Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON, Canada
| | - J Belik
- Departments of Paediatrics and Physiology, Translational Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON, Canada
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Zenko D, Hislop JN. Regulation and trafficking of muscarinic acetylcholine receptors. Neuropharmacology 2017; 136:374-382. [PMID: 29138081 DOI: 10.1016/j.neuropharm.2017.11.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/02/2017] [Accepted: 11/10/2017] [Indexed: 12/31/2022]
Abstract
Fidelity of signal transduction relies on cells expressing the appropriate number of functional receptors. Fluctuation in the total number of muscarinic acetylcholine receptors has been implicated in a range of physiological and pathophysiological processes, and the mechanisms responsible for this regulation represent potential molecular targets for therapeutic intervention. This article will review the current literature on the endocytic trafficking of muscarinic receptors and how knowledge of the trafficking of related receptors might influence future studies. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Dmitry Zenko
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
| | - James N Hislop
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
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Mahavadi S, Sriwai W, Manion O, Grider JR, Murthy KS. Diabetes-induced oxidative stress mediates upregulation of RhoA/Rho kinase pathway and hypercontractility of gastric smooth muscle. PLoS One 2017; 12:e0178574. [PMID: 28678840 PMCID: PMC5497948 DOI: 10.1371/journal.pone.0178574] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/15/2017] [Indexed: 02/07/2023] Open
Abstract
The pathogenesis of diabetes-associated motility disorders are multifactorial and attributed to abnormalities in extrinsic and intrinsic innervation, and a decrease in the number of interstitial cells of Cajal, and nNOS expression and activity. Here we studied the effect of hyperglycemia on smooth muscle function. Using smooth muscles from the fundus of ob/ob mice and of wild type (WT) mice treated with 30 mM glucose (HG), we identified the molecular mechanism by which hyperglycemia upregulates RhoA/Rho kinase pathway and muscle contraction. RhoA expression, Rho kinase activity and muscle contraction were increased, while miR-133a expression was decreased in smooth muscle of ob/ob mice and in smooth muscle treated with HG. Intraperitoneal injections of pre-miR-133a decreased RhoA expression in WT mice and reversed the increase in RhoA expression in ob/ob mice. Intraperitoneal injections of antagomiR-133a increased RhoA expression in WT mice and augmented the increase in RhoA expression in ob/ob mice. The effect of pre-miR-133a or antagomiR-133a in vitro in smooth muscle treated with HG was similar to that obtained in vivo, suggesting that the expression of RhoA is negatively regulated by miR-133a and a decrease in miR-133a expression in diabetes causes an increase in RhoA expression. Oxidative stress (levels of reactive oxygen species and hydrogen peroxide, and expression of superoxide dismutase 1 and NADPH oxidase 4) was increased in smooth muscle of ob/ob mice and in HG-treated smooth muscle. Treatment of ob/ob mice with N-acetylcysteine (NAC) in vivo or addition of NAC in vitro to HG-treated smooth muscle reversed the effect of glucose on the expression of miR-133a and RhoA, Rho kinase activity and muscle contraction. NAC treatment also reversed the decrease in gastric emptying in ob/ob mice. We conclude that oxidative stress in diabetes causes a decrease in miR-133a expression leading to an increase in RhoA/Rho kinase pathway and muscle contraction.
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Affiliation(s)
- Sunila Mahavadi
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Wimolpak Sriwai
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Olivia Manion
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - John R. Grider
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Karnam S. Murthy
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Bader S, Lottig L, Diener M. Stimulation of Na + -K + -pump currents by epithelial nicotinic receptors in rat colon. Br J Pharmacol 2017; 174:880-892. [PMID: 28239845 DOI: 10.1111/bph.13761] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Acetylcholine-induced epithelial Cl- secretion is generally thought to be mediated by epithelial muscarinic receptors and nicotinic receptors on secretomotor neurons. However, recent data have shown expression of nicotinic receptors by intestinal epithelium and the stimulation of Cl- secretion by nicotine, in the presence of the neurotoxin, tetrodotoxin. Here, we aimed to identify the transporters activated by epithelial nicotinic receptors and to clarify their role in cholinergic regulation of intestinal ion transport. EXPERIMENTAL APPROACH Ussing chamber experiments were performed, using rat distal colon with intact epithelia. Epithelia were basolaterally depolarized to measure currents across the apical membrane. Apically permeabilized tissue was also used to measure currents across the basolateral membrane in the presence of tetrodotoxin. KEY RESULTS Nicotine had no effect on currents through Cl- channels in the apical membrane or on currents through K+ channels in the apical or the basolateral membrane. Instead, nicotine stimulated the Na+ -K+ -pump as indicated by Na+ -dependency and sensitivity of the nicotine-induced current across the basolateral membrane to cardiac steroids. Effects of nicotine were inhibited by nicotinic receptor antagonists such as hexamethonium and mimicked by dimethyl-4-phenylpiperazinium, a chemically different nicotinic agonist. Simultaneous stimulation of epithelial muscarinic and nicotinic receptors led to a strong potentiation of transepithelial Cl- secretion. CONCLUSIONS AND IMPLICATIONS These results suggest a novel concept for the cholinergic regulation of transepithelial ion transport by costimulation of muscarinic and nicotinic epithelial receptors and a unique role of nicotinic receptors controlling the activity of the Na+ -K+ -ATPase.
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Affiliation(s)
- Sandra Bader
- Institute of Veterinary Physiology and Biochemistry, Justus-Liebig-University Giessen, Gießen, Germany
| | - Lena Lottig
- Institute of Veterinary Physiology and Biochemistry, Justus-Liebig-University Giessen, Gießen, Germany
| | - Martin Diener
- Institute of Veterinary Physiology and Biochemistry, Justus-Liebig-University Giessen, Gießen, Germany
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11
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Feng D, Nan H, Wang W, Yan L, Du P, Zuo L, Zhang K, Zhao M, Cui G. Expression and alteration of BK Ca channels in the sphincter of Oddi's from rabbits with hypercholesterolemia. Channels (Austin) 2017; 11:236-244. [PMID: 28102743 DOI: 10.1080/19336950.2017.1279369] [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] [Indexed: 12/15/2022] Open
Abstract
This study aimed to investigate the expression and function of BKCa channels in the Sphincter of Oddi (SO) in a rabbit model of hypercholesterolemia (HC). New Zealand white rabbits were randomly divided into 2 groups: the control group was fed standard chow (n = 18) whereas the high-cholesterol group was fed cholesterol-enriched chow containing 1.5% cholesterol (n = 18). The serum cholesterol level was significantly greater in the HC groups than in the control group, but there was no significant difference in body weight between the control and HC groups. Although the total protein expression of BKCa α- and β1-subunit was not significantly different between the control and HC groups, the Tyr-phosphorylation of BKCa α-subunit was significantly decreased in the HC group than in the control group. In addition, hypercholesterolemia significantly increased Acetylcholine (ACh)-induced contraction of the SO rings. Pretreatment with 30 μM NS1619, a BKCa channel agonist, significantly reduced ACh-induced contraction of the SO rings in HC rabbits. Moreover, pretreatment with 100 μM Na3OV4, a protein tyrosine phosphatase inhibitor, significantly reduced ACh-induced contraction of the SO rings in HC rabbits, whereas it significantly increased upon pretreating with 10 μM Genistein, a tyrosine kinase inhibitor. Whole-cell patch clamp recordings showed that BKCa current density was significantly lower in SOSMCs from HC group than that from control group. Our findings suggest that hypercholesterolemia-induced downregulation of BKCa channel, and Tyr-phosphorylation of BKCa α-subunit may contribute to the hyperresponsiveness of the SO ring in HC rabbits.
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Affiliation(s)
- Dan Feng
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Haiyan Nan
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Wen Wang
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Linfeng Yan
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Pang Du
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Lin Zuo
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
| | - Kun Zhang
- b Department of Pharmacology, School of Pharmacy , Fourth Military Medical University , Xi'an , China
| | - Minggao Zhao
- b Department of Pharmacology, School of Pharmacy , Fourth Military Medical University , Xi'an , China
| | - Guangbin Cui
- a Department of Radiology , Tangdu Hospital, Fourth Military Medical University , Xi'an , China
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12
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Bhattacharya S, McElhanon KE, Gushchina LV, Weisleder N. Role of phosphatidylinositol-4,5-bisphosphate 3-kinase signaling in vesicular trafficking. Life Sci 2016; 167:39-45. [PMID: 27760304 DOI: 10.1016/j.lfs.2016.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/13/2016] [Accepted: 10/14/2016] [Indexed: 02/07/2023]
Abstract
Phosphatidylinositol-4,5-bisphosphate 3-kinases (PI3Ks) are regulatory enzymes involved in the generation of lipid species that modulate cellular signaling pathways through downstream effectors to influence a variety of cellular functions. Years of intensive study of PI3Ks have produced a significant body of literature in many areas, including that PI3K can mediate intracellular vesicular trafficking and through these actions contribute to a number of important physiological functions. This review focuses on the crucial roles that PI3K and AKT, a major downstream partner of PI3K, play in the regulation of vesicle trafficking during various forms of vesicular endocytosis and exocytosis.
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Affiliation(s)
- Sayak Bhattacharya
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W. 12th Ave., Columbus, OH 43210-1252, United States
| | - Kevin E McElhanon
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W. 12th Ave., Columbus, OH 43210-1252, United States
| | - Liubov V Gushchina
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W. 12th Ave., Columbus, OH 43210-1252, United States
| | - Noah Weisleder
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W. 12th Ave., Columbus, OH 43210-1252, United States.
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Sobchak C, Fajardo AF, Shifrin Y, Pan J, Belik J. Gastric and pyloric sphincter muscle function and the developmental-dependent regulation of gastric content emptying in the rat. Am J Physiol Gastrointest Liver Physiol 2016; 310:G1169-75. [PMID: 27125274 DOI: 10.1152/ajpgi.00046.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/23/2016] [Indexed: 01/31/2023]
Abstract
Feeding intolerance is a common issue in the care of preterm neonates. The condition manifests as delayed emptying of gastric contents and represents a therapeutic challenge, since the factors accounting for its manifestations are unknown. The main goal of this study was to comparatively investigate the age-related function of rat gastric and pyloric smooth muscle and their putative regulators. We hypothesized that a reduced gastric muscle contraction potential early in life contributes to the delayed gastric emptying of the newborn. Newborn and adult rat gastric (fundus) and pyloric sphincter tissues were comparatively studied in vitro. Shortening of the tissue-specific dissociated smooth muscle cell was evaluated, and expression of the key regulatory proteins Rho-associated kinase 2 and myosin light chain kinase was determined. Gastric and pyloric smooth muscle cell shortening was significantly greater in the adult than the respective newborn counterpart. Expression of myosin light chain kinase and Rho-associated kinase 2 was developmentally regulated and increased with age. Pyloric sphincter muscle expresses a higher neuronal nitric oxide synthase and phosphorylated vasodilator-stimulated phosphoprotein content in newborn than adult tissue. Compared with later in life, the newborn rat gastropyloric muscle has a Ca(2+)-related reduced potential for contraction and the pyloric sphincter relaxation-dependent modulators are overexpressed. To the extent that these rodent data can be extrapolated to humans, the delayed gastric emptying in the newborn reflects reduced stomach muscle contraction potential, as opposed to increased pyloric sphincter tone.
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Affiliation(s)
- Curtis Sobchak
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada; and
| | - A Felipe Fajardo
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada; and
| | - Yulia Shifrin
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada; and
| | - Jingyi Pan
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada; and
| | - Jaques Belik
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada; and Department of Paediatrics and Physiology, University of Toronto, Toronto, Ontario, Canada
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14
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Prendergast C, Quayle J, Burdyga T, Wray S. Atherosclerosis differentially affects calcium signalling in endothelial cells from aortic arch and thoracic aorta in Apolipoprotein E knockout mice. Physiol Rep 2014; 2:2/10/e12171. [PMID: 25344475 PMCID: PMC4254096 DOI: 10.14814/phy2.12171] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Apolipoprotein‐E knockout (ApoE−/−) mice develop hypercholesterolemia and are a useful model of atherosclerosis. Hypercholesterolemia alters intracellular Ca2+ signalling in vascular endothelial cells but our understanding of these changes, especially in the early stages of the disease process, is limited. We therefore determined whether carbachol‐mediated endothelial Ca2+ signals differ in plaque‐prone aortic arch compared to plaque‐resistant thoracic aorta, of wild‐type and ApoE−/− mice, and how this is affected by age and the presence of hypercholesterolemia. The extent of plaque development was determined using en‐face staining with Sudan IV. Tissues were obtained from wild‐type and ApoE−/− mice at 10 weeks (pre‐plaques) and 24 weeks (established plaques). We found that even before development of plaques, significantly increased Ca2+ responses were observed in arch endothelial cells. Even with aging and plaque formation, ApoE−/− thoracic responses were little changed, however a significantly enhanced Ca2+ response was observed in arch, both adjacent to and away from lesions. In wild‐type mice of any age, 1–2% of cells had oscillatory Ca2+ responses. In young ApoE−/− and plaque‐free regions of older ApoE−/−, this is unchanged. However a significant increase in oscillations (~13–15%) occurred in thoracic and arch cells adjacent to lesions in older mice. Our data suggest that Ca2+ signals in endothelial cells show specific changes both before and with plaque formation, that these changes are greatest in plaque‐prone aortic arch cells, and that these changes will contribute to the reported deterioration of endothelium in atherosclerosis. We have investigated aortic endothelial cell calcium signalling changes in the Apolipoprotein E knockout mouse model of atherosclerosis. Our data show that calcium signals in endothelial cells undergo specific changes both before and with plaque formation, that these changes are greater in plaque‐prone aortic arch than in plaque‐resistant thoracic aorta, and that these changes will contribute to the reported deterioration of endothelium in atherosclerosis.
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Affiliation(s)
- Clodagh Prendergast
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - John Quayle
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Theodor Burdyga
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Susan Wray
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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15
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Al-Shboul O, Nalli AD, Kumar DP, Zhou R, Mahavadi S, Kuemmerle JF, Grider JR, Murthy KS. Jun kinase-induced overexpression of leukemia-associated Rho GEF (LARG) mediates sustained hypercontraction of longitudinal smooth muscle in inflammation. Am J Physiol Cell Physiol 2014; 306:C1129-41. [PMID: 24740538 DOI: 10.1152/ajpcell.00021.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The signaling pathways mediating sustained contraction of mouse colonic longitudinal smooth muscle and the mechanisms involved in hypercontractility of this muscle layer in response to cytokines and TNBS-induced colitis have not been fully explored. In control longitudinal smooth muscle cells, ACh acting via m3 receptors activated sequentially Gα12, RhoGEF (LARG), and the RhoA/Rho kinase pathway. There was abundant expression of MYPT1, minimal expression of CPI-17, and a notable absence of a PKC/CPI-17 pathway. LARG expression was increased in longitudinal muscle cells isolated from muscle strips cultured for 24 h with IL-1β or TNF-α or obtained from the colon of TNBS-treated mice. The increase in LARG expression was accompanied by a significant increase in ACh-stimulated Rho kinase and ZIP kinase activities, and sustained muscle contraction. The increase in LARG expression, Rho kinase and ZIP kinase activities, and sustained muscle contraction was abolished in cells pretreated with the Jun kinase inhibitor, SP600125. Expression of the MLCP activator, telokin, and MLCP activity were also decreased in longitudinal muscle cells from TNBS-treated mice or from strips treated with IL-1β or TNF-α. In contrast, previous studies had shown that sustained contraction in circular smooth muscle is mediated by sequential activation of Gα13, p115RhoGEF, and dual RhoA-dependent pathways involving phosphorylation of MYPT1 and CPI-17. In colonic circular smooth muscle cells isolated from TNBS-treated mice or from strips treated with IL-1β or TNF-α, CPI-17 expression and sustained muscle contraction were decreased. The disparate changes in the two muscle layers contribute to intestinal dysmotility during inflammation.
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Affiliation(s)
- Othman Al-Shboul
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - Ancy D Nalli
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - Divya P Kumar
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - Ruizhe Zhou
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - Sunila Mahavadi
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - John F Kuemmerle
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - John R Grider
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
| | - Karnam S Murthy
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, Virginia
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16
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Sánchez-Fernández G, Cabezudo S, García-Hoz C, Benincá C, Aragay AM, Mayor F, Ribas C. Gαq signalling: the new and the old. Cell Signal 2014; 26:833-48. [PMID: 24440667 DOI: 10.1016/j.cellsig.2014.01.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 01/09/2014] [Indexed: 01/25/2023]
Abstract
In the last few years the interactome of Gαq has expanded considerably, contributing to improve our understanding of the cellular and physiological events controlled by this G alpha subunit. The availability of high-resolution crystal structures has led the identification of an effector-binding region within the surface of Gαq that is able to recognise a variety of effector proteins. Consequently, it has been possible to ascribe different Gαq functions to specific cellular players and to identify important processes that are triggered independently of the canonical activation of phospholipase Cβ (PLCβ), the first identified Gαq effector. Novel effectors include p63RhoGEF, that provides a link between G protein-coupled receptors and RhoA activation, phosphatidylinositol 3-kinase (PI3K), implicated in the regulation of the Akt pathway, or the cold-activated TRPM8 channel, which is directly inhibited upon Gαq binding. Recently, the activation of ERK5 MAPK by Gq-coupled receptors has also been described as a novel PLCβ-independent signalling axis that relies upon the interaction between this G protein and two novel effectors (PKCζ and MEK5). Additionally, the association of Gαq with different regulatory proteins can modulate its effector coupling ability and, therefore, its signalling potential. Regulators include accessory proteins that facilitate effector activation or, alternatively, inhibitory proteins that downregulate effector binding or promote signal termination. Moreover, Gαq is known to interact with several components of the cytoskeleton as well as with important organisers of membrane microdomains, which suggests that efficient signalling complexes might be confined to specific subcellular environments. Overall, the complex interaction network of Gαq underlies an ever-expanding functional diversity that puts forward this G alpha subunit as a major player in the control of physiological functions and in the development of different pathological situations.
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Affiliation(s)
- Guzmán Sánchez-Fernández
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Sofía Cabezudo
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Carlota García-Hoz
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | | | - Anna M Aragay
- Department of Cell Biology, Molecular Biology Institute of Barcelona, Spain
| | - Federico Mayor
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain.
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17
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Mahavadi S, Bhattacharya S, Kumar DP, Clay C, Ross G, Akbarali HI, Grider JR, Murthy KS. Increased PDE5 activity and decreased Rho kinase and PKC activities in colonic muscle from caveolin-1-/- mice impair the peristaltic reflex and propulsion. Am J Physiol Gastrointest Liver Physiol 2013; 305:G964-74. [PMID: 24157969 PMCID: PMC3882438 DOI: 10.1152/ajpgi.00165.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Caveolae are specialized regions of the plasma membrane that concentrate receptors and associated signaling molecules critical in regulation of cellular response to transmitters and hormones. We have determined the effects of caveolin-1 (Cav-1) deletion, caveolin-1 siRNA, and caveolar disruption in mice on the signaling pathways that mediate contraction and relaxation in colonic smooth muscle and on the components of the peristaltic reflex in isolated tissue and propulsion in intact colonic segments. In Cav-1-/- mice, both relaxation and contraction were decreased in smooth muscle cells and muscle strips, as well as during both phases of the peristaltic reflex and colonic propulsion. The decrease in relaxation in response to the nitric oxide (NO) donor was accompanied by a decrease in cGMP levels and an increase in phosphodiesterase 5 (PDE5) activity. Relaxation by a PDE5-resistant cGMP analog was not affected in smooth muscle of Cav-1-/- mice, suggesting that inhibition of relaxation was due to augmentation of PDE5 activity. Similar effects on relaxation, PDE5 and cGMP were obtained in muscle cells upon disruption of caveolae by methyl-β-cyclodextrin or suppression of Cav-1. Sustained contraction mediated via inhibition of myosin light chain phosphatase (MLCP) activity is regulated by Rho kinase and PKC via phosphorylation of two endogenous inhibitors of MLCP: myosin phosphatase-targeting subunit (MYPT1) and 17-kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17), respectively. The activity of both enzymes and phosphorylation of MYPT1 and CPI-17 were decreased in smooth muscle from Cav-1-/- mice. We conclude that the integrity of caveolae is essential for contractile and relaxant activity in colonic smooth muscle and the maintenance of neuromuscular function at organ level.
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Affiliation(s)
- Sunila Mahavadi
- Box 980551, Dept. of Physiology, School of Medicine, Virginia Commonwealth Univ., Richmond, VA 23298-0551.
| | | | | | | | | | - Hamid I. Akbarali
- Departments of 1Physiology and Biophysics, ,2Pharmacology and Toxicology, and ,3Medicine, and VCU Program in Enteric Neuromuscular Science (VPENS), School of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - John R. Grider
- Departments of 1Physiology and Biophysics, ,3Medicine, and VCU Program in Enteric Neuromuscular Science (VPENS), School of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Karnam S. Murthy
- Departments of 1Physiology and Biophysics, ,3Medicine, and VCU Program in Enteric Neuromuscular Science (VPENS), School of Medicine, Virginia Commonwealth University, Richmond, Virginia
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