1
|
Davis MJ, Kim HJ, Zawieja SD, Castorena-Gonzalez JA, Gui P, Li M, Saunders BT, Zinselmeyer BH, Randolph GJ, Remedi MS, Nichols CG. Kir6.1-dependent K ATP channels in lymphatic smooth muscle and vessel dysfunction in mice with Kir6.1 gain-of-function. J Physiol 2020; 598:3107-3127. [PMID: 32372450 DOI: 10.1113/jp279612] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/01/2020] [Indexed: 02/06/2023] Open
Abstract
KEY POINTS Spontaneous contractions are essential for normal lymph transport and these contractions are exquisitely sensitive to the KATP channel activator pinacidil. KATP channel Kir6.1 and SUR2B subunits are expressed in mouse lymphatic smooth muscle (LSM) and form functional KATP channels as verified by electrophysiological techniques. Global deletion of Kir6.1 or SUR2 subunits results in severely impaired lymphatic contractile responses to pinacidil. Smooth muscle-specific expression of Kir6.1 gain-of-function mutant (GoF) subunits results in profound lymphatic contractile dysfunction and LSM hyperpolarization that is partially rescued by the KATP inhibitor glibenclamide. In contrast, lymphatic endothelial-specific expression of Kir6.1 GoF has essentially no effect on lymphatic contractile function. The high sensitivity of LSM to KATP channel GoF offers an explanation for the lymphoedema observed in patients with Cantú syndrome, a disorder caused by gain-of-function mutations in genes encoding Kir6.1 or SUR2, and suggests that glibenclamide may be an appropriate therapeutic agent. ABSTRACT This study aimed to understand the functional expression of KATP channel subunits in distinct lymphatic cell types, and assess the consequences of altered KATP channel activity on lymphatic pump function. KATP channel subunits Kir6.1 and SUR2B were expressed in mouse lymphatic muscle by PCR, but only Kir6.1 was expressed in lymphatic endothelium. Spontaneous contractions of popliteal lymphatics from wild-type (WT) (C57BL/6J) mice, assessed by pressure myography, were very sensitive to inhibition by the SUR2-specific KATP channel activator pinacidil, which hyperpolarized both mouse and human lymphatic smooth muscle (LSM). In vessels from mice with deletion of Kir6.1 (Kir6.1-/- ) or SUR2 (SUR2[STOP]) subunits, contractile parameters were not significantly different from those of WT vessels, suggesting that basal KATP channel activity in LSM is not an essential component of the lymphatic pacemaker, and does not exert a strong influence over contractile strength. However, these vessels were >100-fold less sensitive than WT vessels to pinacidil. Smooth muscle-specific expression of a Kir6.1 gain-of-function (GoF) subunit resulted in severely impaired lymphatic contractions and hyperpolarized LSM. Membrane potential and contractile activity was partially restored by the KATP channel inhibitor glibenclamide. In contrast, lymphatic endothelium-specific expression of Kir6.1 GoF subunits had negligible effects on lymphatic contraction frequency or amplitude. Our results demonstrate a high sensitivity of lymphatic contractility to KATP channel activators through activation of Kir6.1/SUR2-dependent channels in LSM. In addition, they offer an explanation for the lymphoedema observed in patients with Cantú syndrome, a disorder caused by gain-of-function mutations in genes encoding Kir6.1/SUR2.
Collapse
Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Hae Jin Kim
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Jorge A Castorena-Gonzalez
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Brian T Saunders
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Bernd H Zinselmeyer
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Gwendalyn J Randolph
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Maria S Remedi
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, 63110, USA
| |
Collapse
|
2
|
To KHT, Gui P, Li M, Zawieja SD, Castorena-Gonzalez JA, Davis MJ. T-type, but not L-type, voltage-gated calcium channels are dispensable for lymphatic pacemaking and spontaneous contractions. Sci Rep 2020; 10:70. [PMID: 31919478 PMCID: PMC6952455 DOI: 10.1038/s41598-019-56953-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 12/10/2019] [Indexed: 12/28/2022] Open
Abstract
The spontaneous contractions of collecting lymphatic vessels provide an essential propulsive force to return lymph centrally. These contractions are driven by an intrinsic electrical pacemaker, working through an unknown underlying ionic mechanism that becomes compromised in some forms of lymphedema. In previous studies, T-type voltage-gated Ca2+ channels (VGCCs) were implicated in this pacemaking mechanism, based on the effects of the reputedly selective T-type VGCC inhibitors mibefradil and Ni2+. Our goal was to test this idea in a more definitive way using genetic knock out mice. First, we demonstrated through both PCR and immunostaining that mouse lymphatic muscle cells expressed Cav3.1 and Cav3.2 and produced functional T-type VGCC currents when patch clamped. We then employed genetic deletion strategies to selectively test the roles of each T-type VGCC isoform in the regulation of lymphatic pacemaking. Surprisingly, global deletion of either, or both, isoform(s) was without significant effect on either the frequency, amplitude, or fractional pump flow of lymphatic collectors from two different regions of the mouse, studied ex vivo. Further, both WT and Cav3.1-/-; 3.2-/- double knock-out lymphatic vessels responded similarly to mibefradil and Ni2+, which substantially reduced contraction amplitudes and slightly increased frequencies at almost all pressures in both strains: a pattern consistent with inhibition of L-type rather than T-type VGCCs. Neither T-type VGCC isoform was required for ACh-induced inhibition of contraction, a mechanism by which those channels in smooth muscle are thought to be targets of endothelium-derived nitric oxide. Sharp intracellular electrode measurements in lymphatic smooth muscle revealed only subtle, but not significant, differences in the resting membrane potential and action potential characteristics between vessels from wild-type and Cav3.1-/-; 3.2-/- double knock-out mice. In contrast, smooth-muscle specific deletion of the L-type VGCC, Cav1.2, completely abolished all lymphatic spontaneous contractions. Collectively our results suggest that, although T-type VGCCs are expressed in mouse lymphatic smooth muscle, they do not play a significant role in modulating the frequency of the ionic pacemaker or the amplitude of spontaneous contractions. We conclude that the effects of mibefradil and Ni2+ in other lymphatic preparations are largely or completely explained by off-target effects on L-type VGCCs, which are essential for controlling both the frequency and strength of spontaneous contractions.
Collapse
MESH Headings
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/chemistry
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/deficiency
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Lymphatic Vessels/physiology
- Male
- Membrane Potentials/drug effects
- Mibefradil/pharmacology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/metabolism
- Nickel/pharmacology
- Pacemaker, Artificial
- Rats
- Rats, Wistar
Collapse
Affiliation(s)
- Kim H T To
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Jorge A Castorena-Gonzalez
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA.
| |
Collapse
|
3
|
Zawieja SD, Castorena JA, Gui P, Li M, Bulley SA, Jaggar JH, Rock JR, Davis MJ. Ano1 mediates pressure-sensitive contraction frequency changes in mouse lymphatic collecting vessels. J Gen Physiol 2019; 151:532-554. [PMID: 30862712 PMCID: PMC6445586 DOI: 10.1085/jgp.201812294] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/06/2019] [Indexed: 12/16/2022] Open
Abstract
Lymphatic collecting vessels exhibit spontaneous contractions with a pressure-dependent contraction frequency. The initiation of contraction has been proposed to be mediated by the activity of a Ca2+-activated Cl- channel (CaCC). Here, we show that the canonical CaCC Anoctamin 1 (Ano1, TMEM16a) plays an important role in lymphatic smooth muscle pacemaking. We find that isolated murine lymphatic muscle cells express Ano1, and demonstrate functional CaCC currents that can be inhibited by the Ano1 inhibitor benzbromarone. These currents are absent in lymphatic muscle cells from Cre transgenic mouse lines targeted for Ano1 genetic deletion in smooth muscle. We additionally show that loss of functional Ano1 in murine inguinal-axillary lymphatic vessels, whether through genetic manipulation or pharmacological inhibition, results in an impairment of the pressure-frequency relationship that is attributable to a hyperpolarized resting membrane potential and a significantly depressed diastolic depolarization rate preceding each action potential. These changes are accompanied by alterations in action potential shape and duration, and a reduced duration but increased amplitude of the action potential-induced global "Ca2+ flashes" that precede lymphatic contractions. These findings suggest that an excitatory Cl- current provided by Ano1 is critical for mediating the pressure-sensitive contractile response and is a major component of the murine lymphatic action potential.
Collapse
Affiliation(s)
- Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Jorge A Castorena
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Simon A Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN
| | - Jason R Rock
- Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| |
Collapse
|
4
|
Zawieja S, Castorena J, Gui P, Li M, Jaggar J, Chen SW, Valdivia H, Davis M. The Regulation of Lymphatic Muscle Cell Contractile Activity by Intracellular Calcium Signals. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.520.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Scott Zawieja
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMO
| | - Jorge Castorena
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMO
| | - Peichun Gui
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMO
| | - Min Li
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMO
| | | | - S.R. Wayne Chen
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | | | - Michael Davis
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMO
| |
Collapse
|
5
|
Hald BO, Castorena-Gonzalez JA, Zawieja SD, Gui P, Davis MJ. Electrical Communication in Lymphangions. Biophys J 2018; 115:936-949. [PMID: 30143234 DOI: 10.1016/j.bpj.2018.07.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/02/2018] [Accepted: 07/19/2018] [Indexed: 11/30/2022] Open
Abstract
Contractions of lymphangions, i.e., the segment between two one-way lymphatic valves, generate the pressure gradients that propel lymph back to the circulation. Each lymphangion is comprised of an inner sheet of lymphatic endothelial cells circumscribed by one or more layers of lymphatic muscle cells (LMCs). Each contraction is produced by an LMC action potential (AP) that propagates via gap junctions along the lymphangion. Yet, electrical coupling within and between cell layers and the impact on AP waves is poorly understood. Here, we combine studies in rat and mouse lymphatic vessels with mathematical modeling to show that initiation of AP waves depends on high input resistance (low current drain), whereas propagation depends on morphology and sufficient LMC:LMC coupling. Simulations show that 1) myoendothelial coupling is insignificant to facilitate AP generation and sustain an experimentally measured cross-junctional potential difference of 25 mV, i.e., AP waves propagate along the LMC layer only; 2) LMC:LMC resistance is estimated around 2-10 MΩ but depends on vessel structure and cell-cell coupling, e.g., some degree of LMC overlap protects AP waves against LMC decoupling; 3) the propensity of AP wave initiation is highest around the valves, where the density of LMCs is low; and 4) a single pacemaker cell embedded in the LMC layer must be able to generate very large currents to overcome the current drain from the layer. However, the required current generation to initiate an AP wave is reduced upon stimulation of multiple adjacent LMCs. With stimulation of all LMCs, AP waves can also arise from heterogeneity in the electrical activity of LMCs. The findings advance our understanding of the electrical constraints that underlie initiation of APs in the LMC layer and make testable predictions about how morphology, LMC excitability, and LMC:LMC electrical coupling interact to determine the ability to initiate and propagate AP waves in small lymphatic vessels.
Collapse
Affiliation(s)
- Bjørn Olav Hald
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Jorge Augusto Castorena-Gonzalez
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Scott David Zawieja
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Michael John Davis
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.
| |
Collapse
|
6
|
Gui P, Zawieja S, Li M, Castorena‐Gonzale J, Davis MJ. Improved methods for characterizing ion channel expression in smooth muscle, endothelial and adventitial cells from collecting lymphatic vessels. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.576.1] [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: 11/11/2022]
Affiliation(s)
- Peichun Gui
- University of Missouri‐Columbia School of MedicineColumbiaMO
| | - Scott Zawieja
- University of Missouri‐Columbia School of MedicineColumbiaMO
| | - Min Li
- University of Missouri‐Columbia School of MedicineColumbiaMO
| | | | | |
Collapse
|
7
|
Davis MJ, Castorena‐Gonzale J, Li M, Gui P, Domeier TL, Zawieja S. Are lymphatic contractions initiated and/or coordinated by ICC‐like cells in the lymphatic vessel wall? FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.576.4] [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: 11/11/2022]
Affiliation(s)
| | | | - Min Li
- University of Missouri‐Columbia School of MedicineColumbiaMO
| | - Peichun Gui
- University of Missouri‐Columbia School of MedicineColumbiaMO
| | | | - Scott Zawieja
- University of Missouri‐Columbia School of MedicineColumbiaMO
| |
Collapse
|
8
|
Gui P, Li M, Hill M, Davis M. KCNQ and ERG channels control the rate of diastolic depolarization and electrical pacemaking frequency in lymphatic muscle (666.3). FASEB J 2014. [DOI: 10.1096/fasebj.28.1_supplement.666.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Peichun Gui
- Medical Pharmacology & Physiology University of MissouriCOLUMBIAMOUnited States
| | - Min Li
- Dalton Cardiovascular Research Center University of MissouriCOLUMBIAMOUnited States
| | - Michael Hill
- Dalton Cardiovascular Research Center University of MissouriCOLUMBIAMOUnited States
| | - Michael Davis
- Medical Pharmacology & Physiology University of MissouriCOLUMBIAMOUnited States
| |
Collapse
|
9
|
Gulia J, Navedo MF, Gui P, Chao JT, Mercado JL, Santana LF, Davis MJ. Regulation of L-type calcium channel sparklet activity by c-Src and PKC-α. Am J Physiol Cell Physiol 2013; 305:C568-77. [PMID: 23804206 DOI: 10.1152/ajpcell.00381.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activity of persistent Ca²⁺ sparklets, which are characterized by longer and more frequent channel open events than low-activity sparklets, contributes substantially to steady-state Ca²⁺ entry under physiological conditions. Here, we addressed two questions related to the regulation of Ca²⁺ sparklets by PKC-α and c-Src, both of which increase whole cell Cav1.2 current: 1) Does c-Src activation enhance persistent Ca²⁺ sparklet activity? 2) Does PKC-α activate c-Src to produce persistent Ca²⁺ sparklets? With the use of total internal reflection fluorescence microscopy, Ca²⁺ sparklets were recorded from voltage-clamped tsA-201 cells coexpressing wild-type (WT) or mutant Cav1.2c (the neuronal isoform of Cav1.2) constructs ± active or inactive PKC-α/c-Src. Cells expressing Cav1.2c exhibited both low-activity and persistent Ca²⁺ sparklets. Persistent Ca²⁺ sparklet activity was significantly reduced by acute application of the c-Src inhibitor PP2 or coexpression of kinase-dead c-Src. Cav1.2c constructs mutated at one of two COOH-terminal residues (Y²¹²²F and Y²¹³⁹F) were used to test the effect of blocking putative phosphorylation sites for c-Src. Expression of Y²¹²²F but not Y²¹³⁹F Cav1.2c abrogated the potentiating effect of c-Src on Ca²⁺ sparklet activity. We could not detect a significant change in persistent Ca²⁺ sparklet activity or density in cells coexpressing Cav1.2c + PKC-α, regardless of whether WT or Y²¹²²F Cav1.2c was used, or after PP2 application, suggesting that PKC-α does not act upstream of c-Src to produce persistent Ca²⁺ sparklets. However, our results indicate that persistent Ca²⁺ sparklet activity is promoted by the action of c-Src on residue Y²¹²² of the Cav1.2c COOH terminus.
Collapse
Affiliation(s)
- Jyoti Gulia
- Department of Biological Engineering University of Missouri, Columbia, Missouri, USA
| | | | | | | | | | | | | |
Collapse
|
10
|
Gui P, Braun AP, Davis MJ. Integrin‐dependent and ‐independent potentiation of BKCa channel current by cell stretch. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.870.11] [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: 11/11/2022]
Affiliation(s)
- Peichun Gui
- Dept. of Medical Pharmcology & PhysiologyU of Missouri-ColumbiaColumbiaMO
| | | | - Michael J Davis
- Dept. of Medical Pharmcology & PhysiologyU of Missouri-ColumbiaColumbiaMO
| |
Collapse
|
11
|
Gui P, Zamponi GW, Davis GE, Davis MJ. Integrin‐dependent and ‐independent potentiation of L‐type Calcium Current (Cav1.2) by cell stretch. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1042.2] [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: 11/11/2022]
Affiliation(s)
- Peichun Gui
- Dept. of Medical Pharmaco. & Physiol.U of Missouri‐ColumbiaColumbiaMO
| | | | - George E Davis
- Dept. of Medical Pharmaco. & Physiol.U of Missouri‐ColumbiaColumbiaMO
| | - Michael J. Davis
- Dept. of Medical Pharmaco. & Physiol.U of Missouri‐ColumbiaColumbiaMO
| |
Collapse
|
12
|
Abstract
Engagement of α(5)β(1)-integrin by fibronectin (FN) acutely enhances Cav1.2 channel (Ca(L)) current in rat arteriolar smooth muscle and human embryonic kidney cells (HEK293-T) expressing Ca(L). Using coimmunoprecipitation strategies, we show that coassociation of Ca(L) with α(5)- or β(1)-integrin in HEK293-T cells is specific and depends on cell adhesion to FN. In rat arteriolar smooth muscle, coassociations between Ca(L) and α(5)β(1)-integrin and between Ca(L) and phosphorylated c-Src are also revealed and enhanced by FN treatment. Using site-directed mutagenesis of Ca(L) heterologously expressed in HEK293-T cells, we identified two regions of Ca(L) required for these interactions: 1) COOH-terminal residues Ser(1901) and Tyr(2122), known to be phosphorylated by protein kinase A (PKA) and c-Src, respectively; and 2) two proline-rich domains (PRDs) near the middle of the COOH terminus. Immunofluorescence confocal imaging revealed a moderate degree of wild-type Ca(L) colocalization with β(1)-integrin on the plasma membrane. Collectively, our results strongly suggest that 1) upon ligation by FN, Ca(L) associates with α(5)β(1)-integrin in a macromolecular complex including PKA, c-Src, and potentially other protein kinases; 2) phosphorylation of Ca(L) at Y(2122) and/or S(1901) is required for association of Ca(L) with α(5)β(1)-integrin; and 3) c-Src, via binding to PRDs that reside in the II-III linker region and/or the COOH terminus of Ca(L), mediates current potentiation following α(5)β(1)-integrin engagement. These findings provide new evidence for how interactions between α(5)β(1)-integrin and FN can modulate Ca(L) entry and consequently alter the physiological function of multiple types of excitable cells.
Collapse
Affiliation(s)
- Jun-Tzu Chao
- Dept. of Medical Pharmacology and Physiology, M451 Med. Sci. Bldg., Univ. of Missouri, Columbia, 1 Hospital Dr., Columbia, MO 65211, USA
| | | | | | | | | |
Collapse
|
13
|
Gui P, Zamponi GW, Davis GE, Davis MJ. Integrin-Dependent and -Independent Potentiation of L-type Calcium Current (Cav1.2) by Cell Stretch. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.1755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
|
14
|
Yang Y, Wu X, Gui P, Wu J, Sheng JZ, Ling S, Braun AP, Davis GE, Davis MJ. Alpha5beta1 integrin engagement increases large conductance, Ca2+-activated K+ channel current and Ca2+ sensitivity through c-src-mediated channel phosphorylation. J Biol Chem 2009; 285:131-41. [PMID: 19887442 DOI: 10.1074/jbc.m109.033506] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Large conductance, calcium-activated K(+) (BK) channels are important regulators of cell excitability and recognized targets of intracellular kinases. BK channel modulation by tyrosine kinases, including focal adhesion kinase and c-src, suggests their potential involvement in integrin signaling. Recently, we found that fibronectin, an endogenous alpha5beta1 integrin ligand, enhances BK channel current through both Ca(2+)- and phosphorylation-dependent mechanisms in vascular smooth muscle. Here, we show that macroscopic currents from HEK 293 cells expressing murine BK channel alpha-subunits (mSlo) are acutely potentiated following alpha5beta1 integrin activation. The effect occurs in a Ca(2+)-dependent manner, 1-3 min after integrin engagement. After integrin activation, normalized conductance-voltage relations for mSlo are left-shifted at free Ca(2+) concentrations >or=1 microm. Overexpression of human c-src with mSlo, in the absence of integrin activation, leads to similar shifts in mSlo Ca(2+) sensitivity, whereas overexpression of catalytically inactive c-src blocks integrin-induced potentiation. However, neither integrin activation nor c-src overexpression potentiates current in BK channels containing a point mutation at Tyr-766. Biochemical tests confirmed the critical importance of residue Tyr-766 in integrin-induced channel phosphorylation. Thus, BK channel activity is enhanced by alpha5beta1 integrin activation, likely through an intracellular signaling pathway involving c-src phosphorylation of the channel alpha-subunit at Tyr-766. The net result is increased current amplitude, enhanced Ca(2+) sensitivity, and rate of activation of the BK channel, which would collectively promote smooth muscle hyperpolarization in response to integrin-extracellular matrix interactions.
Collapse
Affiliation(s)
- Yan Yang
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Gui P, Zamponi GW, Davis GE, Davis MJ. Integrin‐dependent and ‐independent potentiation of L‐type Calcium Current (Cav1.2) by cell stretch. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.1000.18] [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: 11/11/2022]
Affiliation(s)
- Peichun Gui
- Department of Medical Pharmacology & PhysiologyUniversity of Missouri‐Columbia School of MedicineColumbiaMO
| | - Gerald W Zamponi
- Molecular Neuroscience Research GroupUniversity of CalgaryAlbertaCanada
| | - George E Davis
- Department of Medical Pharmacology & PhysiologyUniversity of Missouri‐Columbia School of MedicineColumbiaMO
| | - Michael J Davis
- Department of Medical Pharmacology & PhysiologyUniversity of Missouri‐Columbia School of MedicineColumbiaMO
| |
Collapse
|
16
|
Gulia J, Gui P, Chao J, Navedo MF, Santana LF, Davis MJ. Roles of c‐Src and PKC in production of persistent calcium sparklet activity. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.1000.19] [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: 11/11/2022]
Affiliation(s)
| | - Peichun Gui
- Medical Physiology and PharmacologyUniversity of MissouriColumbiaMO
| | - Jun‐Tzu Chao
- Medical Physiology and PharmacologyUniversity of MissouriColumbiaMO
| | | | - Luis F Santana
- Physiology and BiophysicsUniversity of WashingtonSeattleWA
| | - Michael J Davis
- Medical Physiology and PharmacologyUniversity of MissouriColumbiaMO
| |
Collapse
|
17
|
Chao JS, Gui P, Zamponi GW, Davis GE, Davis MJ. Spatial Interaction of the L‐type Calcium Channel with α
5
β
1
Integrin. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1143.1] [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: 11/11/2022]
Affiliation(s)
- J‐T. S. Chao
- Medical Pharmacology and PhysiologyUniversity of Missouri‐ColumbiaColumbiaMO
| | - P. Gui
- Medical Pharmacology and PhysiologyUniversity of Missouri‐ColumbiaColumbiaMO
| | - G. W. Zamponi
- Physiology and BiophysicsUniversity of CalgaryCalgaryCanada
| | - G. E. Davis
- Medical Pharmacology and PhysiologyUniversity of Missouri‐ColumbiaColumbiaMO
| | - M. J. Davis
- Medical Pharmacology and PhysiologyUniversity of Missouri‐ColumbiaColumbiaMO
| |
Collapse
|
18
|
Davis MJ, Yang Y, Wu X, Gui P, Sohma Y, Meininger GA, Davis GE, Braun AP. Potentiation of BK Channels by α5β1 Integrin Activation in Arteriolar Smooth Muscle. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1145.3] [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: 11/11/2022]
Affiliation(s)
| | - Yan Yang
- Med Pharmacology & PhysiologyUniversity of MissouriColumbiaMO
| | - Xin Wu
- Systems BiologyTexas A&M HSCCollege StationTX
| | - Peichun Gui
- Med Pharmacology & PhysiologyUniversity of MissouriColumbiaMO
| | | | | | - George E Davis
- Med Pharmacology & PhysiologyUniversity of MissouriColumbiaMO
| | | |
Collapse
|
19
|
Wu X, Yang Y, Gui P, Sohma Y, Meininger GA, Davis GE, Braun AP, Davis MJ. Potentiation of large conductance, Ca2+-activated K+ (BK) channels by alpha5beta1 integrin activation in arteriolar smooth muscle. J Physiol 2008; 586:1699-713. [PMID: 18218680 DOI: 10.1113/jphysiol.2007.149500] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Injury/degradation of the extracellular matrix (ECM) is associated with vascular wall remodelling and impaired reactivity, a process in which altered ECM-integrin interactions play key roles. Previously, we found that peptides containing the RGD integrin-binding sequence produce sustained vasodilatation of rat skeletal muscle arterioles. Here, we tested the hypothesis that RGD ligands work through alpha5beta1 integrin to modulate the activity of large conductance, Ca(2+)-activated K(+) (BK) channels in arteriolar smooth muscle. K(+) currents were recorded in single arteriolar myocytes using whole-cell and single-channel patch clamp methods. Activation of alpha5beta1 integrin by an appropriate, insoluble alpha5beta1 antibody resulted in a 30-50% increase in the amplitude of iberiotoxin (IBTX)-sensitive, whole-cell K(+) current. Current potentiation occurred 1-8 min after bead-antibody application to the cell surface. Similarly, the endogenous alpha5beta1 integrin ligand fibronectin (FN) potentiated IBTX-sensitive K(+) current by 26%. Current potentiation was blocked by the c-Src inhibitor PP2 but not by PP3 (0.1-1 mum). In cell-attached patches, number of open channels x open probability (NP(o)) of a 230-250 pS K(+) channel was significantly increased after FN application locally to the external surface of cell-attached patches through the recording pipette. In excised, inside-out patches, the same method of FN application led to large, significant increases in NP(o) and caused a leftward shift in the NP(o)-voltage relationship at constant [Ca(2+)]. PP2 (but not PP3) nearly abolished the effect of FN on channel activity, suggesting that signalling between the integrin and channel involved an increase in Ca(2+)sensitivity of the channel via a membrane-delimited pathway. The effects of alpha5beta1 integrin activation on both whole-cell and single-channel BK currents could be reproduced in HEK 293 cells expressing the BK channel alpha-subunit. This is the first demonstration at the single-channel level that integrin signalling can regulate an ion channel. Our results show that alpha5beta1 integrin activation potentiates BK channel activity in vascular smooth muscle through both Ca(2+)- and c-Src-dependent mechanisms. This mechanism is likely to play a role in the arteriolar dilatation and impaired vascular reactivity associated with ECM degradation.
Collapse
Affiliation(s)
- Xin Wu
- Department of Medical Pharmacology & Physiology, University of Missouri School of Medicine, 1 Hospital Dr, Rm M451, Columbia, MO 65212, USA.
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Gui P, Zamponi GW, Davis GE, Davis MJ. Potentiation of L‐Type Calcium Current (Cav1.2) by Intracellular Positive Pressure: Role of the Cav1.2 C‐terminus. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a538] [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: 11/11/2022]
Affiliation(s)
- Peichun Gui
- Medical Physiology & PharmacologyUniversity of Missouri‐Columbia School of MedicineM451 Medical SciencesColumbiaMO65201
| | - G W Zamponi
- Molecular Neuroscience Research GroupUniversity of CalgaryCalgaryAlbertaT2N 4N1Canada
| | - G E Davis
- Medical Physiology & PharmacologyUniversity of Missouri‐Columbia School of MedicineM451 Medical SciencesColumbiaMO65201
| | - M J Davis
- Medical Physiology & PharmacologyUniversity of Missouri‐Columbia School of MedicineM451 Medical SciencesColumbiaMO65201
| |
Collapse
|
21
|
Chao J, Gui P, Zamponi GW, Davis MJ. Spatial Association between L‐type Calcium Channels and Integrins. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a914-b] [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: 11/11/2022]
Affiliation(s)
- Jun‐Tzu Chao
- University of Missouri, ColumbiaDept. of Med. Pharmacology & PhysiologyColumbiaMO65212
| | - P Gui
- University of Missouri, ColumbiaDept. of Med. Pharmacology & PhysiologyColumbiaMO65212
| | - G W Zamponi
- University of CalgaryMolecular Neurobiology Research GroupCalgaryT2N4N1Canada
| | - M J Davis
- University of Missouri, ColumbiaDept. of Med. Pharmacology & PhysiologyColumbiaMO65212
| |
Collapse
|
22
|
Gui P, Inamori R, Matsumura M, Inamori Y. Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions. Water Sci Technol 2007; 56:49-55. [PMID: 17802837 DOI: 10.2166/wst.2007.517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.
Collapse
Affiliation(s)
- P Gui
- National Institute for Environmental Studies, 305-8506, Onogawa 16-2, Tsukuba, Japan.
| | | | | | | |
Collapse
|
23
|
Hill M, Murphy T, Gui P, Hwang Y, Howitt L, Davis M, Sun Z. Properties of the large conductance K+ channel (BKCa) in skeletal muscle arterioles. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a846] [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: 11/11/2022]
Affiliation(s)
- Michael Hill
- Dalton Cardiovascular Research CenterUniversity of Missouri134 Research Park DveColumbiaMO65211
| | - Timothy Murphy
- Physiology and PharmacologyUniversity of New South WalesHigh StSydneyAustralia
| | - Peichun Gui
- Medical Pharmacology and PhysiologyUniversity of MissouriHospital DveColumbiaMO65211
| | - Yun Hwang
- Physiology and PharmacologyUniversity of New South WalesHigh StSydneyAustralia
| | - Lauren Howitt
- Physiology and PharmacologyUniversity of New South WalesHigh StSydneyAustralia
| | - Michael Davis
- Medical Pharmacology and PhysiologyUniversity of MissouriHospital DveColumbiaMO65211
| | - Zhe Sun
- Dalton Cardiovascular Research CenterUniversity of Missouri134 Research Park DveColumbiaMO65211
| |
Collapse
|
24
|
Gui P, Wu X, Ling S, Stotz SC, Winkfein RJ, Wilson E, Davis GE, Braun AP, Zamponi GW, Davis MJ. Integrin Receptor Activation Triggers Converging Regulation of Cav1.2 Calcium Channels by c-Src and Protein Kinase A Pathways. J Biol Chem 2006; 281:14015-25. [PMID: 16554304 DOI: 10.1074/jbc.m600433200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
L-type, voltage-gated Ca2+ channels (CaL) play critical roles in brain and muscle cell excitability. Here we show that currents through heterologously expressed neuronal and smooth muscle CaL channel isoforms are acutely potentiated following alpha5beta1 integrin activation. Only the alpha1C pore-forming channel subunit is critical for this process. Truncation and site-directed mutagenesis strategies reveal that regulation of Cav1.2 by alpha5beta1 integrin requires phosphorylation of alpha1C C-terminal residues Ser1901 and Tyr2122. These sites are known to be phosphorylated by protein kinase A (PKA) and c-Src, respectively, and are conserved between rat neuronal (Cav1.2c) and smooth muscle (Cav1.2b) isoforms. Kinase assays are consistent with phosphorylation of these two residues by PKA and c-Src. Following alpha5beta1 integrin activation, native CaL channels in rat arteriolar smooth muscle exhibit potentiation that is completely blocked by combined PKA and Src inhibition. Our results demonstrate that integrin-ECM interactions are a common mechanism for the acute regulation of CaL channels in brain and muscle. These findings are consistent with the growing recognition of the importance of integrin-channel interactions in cellular responses to injury and the acute control of synaptic and blood vessel function.
Collapse
Affiliation(s)
- Peichun Gui
- Department of Medical Pharmacology & Physiology, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Ion channels are regulated by protein phosphorylation and dephosphorylation of serine, threonine, and tyrosine residues. Evidence for regulation of channels by tyrosine phosphorylation comes primarily from investigations of the effects of growth factors, which act through receptor tyrosine kinases. The purpose of the present work is to summarize evidence for the regulation of ion channels by integrins, through their downstream, nonreceptor tyrosine kinases. We review both direct and indirect evidence for this regulation, with particular emphasis on Ca2+-activated K+ and voltage-gated Ca2+ channels. We then discuss the critical roles that cytoskeletal, focal-adhesion, and channel-associated scaffolding proteins may play in localizing nonreceptor tyrosine kinases to the vicinity of ion channels. We conclude by speculating on the physiological significance of these regulatory pathways.
Collapse
Affiliation(s)
- Michael J Davis
- Department of Medical Physiology, Cardiovascular Research Institute, Texas A&M University System Health Science Center, College Station, USA.
| | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
Ion channels are regulated by protein phosphorylation and dephosphorylation of serine, threonine, and tyrosine residues. Evidence for the latter process, tyrosine phosphorylation, has increased substantially since this topic was last reviewed. In this review, we present a comprehensive summary and synthesis of the literature regarding the mechanism and function of ion channel regulation by protein tyrosine kinases and phosphatases. Coverage includes the majority of voltage-gated, ligand-gated, and second messenger-gated channels as well as several types of channels that have not yet been cloned, including store-operated Ca2+ channels, nonselective cation channels, and epithelial Na+ and Cl- channels. Additionally, we discuss the critical roles that channel-associated scaffolding proteins may play in localizing protein tyrosine kinases and phosphatases to the vicinity of ion channels.
Collapse
Affiliation(s)
- M J Davis
- Department of Medical Physiology, Cardiovascular Research Institute, Texas A&M University System Health Science Center, College Station, Texas 77845, USA.
| | | | | | | | | | | | | |
Collapse
|
27
|
Li C, Zhou J, Gui P, He X. Protective effect of rhubarb on endotoxin-induced acute lung injury. J TRADIT CHIN MED 2001; 21:54-8. [PMID: 11360543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
To approach the mechanism of lipopolysaccharide (LPS) in causing acute lung injury (ALI) and the protective effect of rhubarb and dexamethasone, lung specimens were examined with macroscopy, microscopy, electron microscopy and the biological markers of ALI including lung wet/dry weight, the rate of neutrophils and protein content in the pulmonary alveolar lavage fluid, pulmonary capillary permeability and pulmonary alveolar permeability index were observed. The mechanism of the ALI is mainly due to direct injury of alveolar epithelium and pulmonary vascular endothelium. Rhubarb and dexamethasone could significantly reduce the edema of the lung tissue, decrease the red blood cell exudation, neutrophil infiltration and plasma protein exudation in the alveoli and all the biological markers in comparison with the ALI model rats, indicating they have protective action on vascular endothelium and alveolar epithelium.
Collapse
Affiliation(s)
- C Li
- Emergency Department, Beijing Chaoyang Hospital, Beijing 100020
| | | | | | | |
Collapse
|
28
|
Li C, Gui P, He X, Yang H. Actions of NO and INOS on endotoxin induced rat acute lung injury and effect of rhubarb on them. J TRADIT CHIN MED 2000; 20:216-22. [PMID: 11038987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
This study is to explore the actions of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) on endotoxin (lipopolysaccharide, LPS) induced rat acute lung injury (ALI) and effect of Rhubarb on them. LPS was injected into the sublingual vein of male Wistar rats to prepare ALI animal models. The rats were divided into 4 groups: LPS, control, Rhubarb, and dexamethasone. Macroscopic and histopathological examinations of the lung specimens were performed and the biological indexes of lung, including wet weight/dry weight, the rate of neutrophils and protein content in the pulmonary alveolar lavage fluid, pulmonary vascular permeability and pulmonary alveolar permeability were observed. In the mean time, the contents of serum NO and the activities of lung tissue homogenate iNOS were measured. The results showed that in the LPS group, the injury and celluar infiltration in the pulmonary stroma and alveoli were more prominent than that in the control group. Lung wet weight/dry weight, the rate of neutrophils, protein content, pulmonary alveolar permeability, pulmonary vascular permeability were significantly increased (P < 0.01); NO and iNOS were also markedly elevated (P < 0.01). In the groups of dexamethasone and Rhubarb, the histopathological changes were significantly milder, and all the above biological indexes of lung injury and the contents of NO and the activities of iNOS were correspondingly decreased (P < 0.05). The above data demonstrate that NO and iNOS play an important role in the onset of ALI; dexamethasone and Rhubarb interfering treatment can ameliorate lung injury and decrease the concentrations of NO and the activities of iNOS, showing that through inhibiting the levels of NO and the activities of iNOS, these 2 agents exert protective effect on ALI induced LPS.
Collapse
Affiliation(s)
- C Li
- Beijing General Hospital of PLA
| | | | | | | |
Collapse
|