Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels
Background and Purpose. Caveolae act as signalling hubs in endothelial and smooth muscle cells. Caveolar disruption by the membrane cholesterol depleting agent methyl-β-cyclodextrin (M-β-CD) has various functional effects on arteries including (i) impairment of endothelium-dependent relaxation, and...
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PeerJ Inc.
2015-05-01
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| Online Access: | https://peerj.com/articles/966.pdf |
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| author | AY Al-Brakati T Kamishima C Dart JM Quayle |
| author_facet | AY Al-Brakati T Kamishima C Dart JM Quayle |
| author_sort | AY Al-Brakati |
| collection | DOAJ |
| description | Background and Purpose. Caveolae act as signalling hubs in endothelial and smooth muscle cells. Caveolar disruption by the membrane cholesterol depleting agent methyl-β-cyclodextrin (M-β-CD) has various functional effects on arteries including (i) impairment of endothelium-dependent relaxation, and (ii) alteration of smooth muscle cell (SMC) contraction independently of the endothelium. The aim of this study was to explore the effects of M-β-CD on rat femoral arteries.Methods. Isometric force was measured in rat femoral arteries stimulated to contract with a solution containing 20 mM K+ and 200 nM Bay K 8644 (20 K/Bay K) or with one containing 80 mM K+(80 K).Results. Incubation of arteries with M-β-CD (5 mM, 60 min) increased force in response to 20 K/Bay K but not that induced by 80 K. Application of cholesterol saturated M-β-CD (Ch-MCD, 5 mM, 50 min) reversed the effects of M-β-CD. After mechanical removal of endothelial cells M-β-CD caused only a small enhancement of contractions to 20 K/Bay K. This result suggests M-β-CD acts via altering release of an endothelial-derived vasodilator or vasoconstrictor. When nitric oxide synthase was blocked by pre-incubation of arteries with L-NAME (250 µM) the contraction of arteries to 20 K/Bay K was enhanced, and this effect was abolished by pre-treatment with M-β-CD. This suggests M-β-CD is inhibiting endothelial NO release. Inhibition of large conductance voltage- and Ca2+-activated (BKCa) channels with 2 mM TEA+ or 100 nM Iberiotoxin (IbTX) enhanced 20 K/Bay K contractions. L-NAME attenuated the contractile effect of IbTX, as did endothelial removal.Conclusions. Our results suggest caveolar disruption results in decreased release of endothelial-derived nitric oxide in rat femoral artery, resulting in a reduced contribution of BKCa channels to the smooth muscle cell membrane potential, causing depolarisation and contraction. |
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| issn | 2167-8359 |
| language | English |
| last_indexed | 2024-03-09T07:03:44Z |
| publishDate | 2015-05-01 |
| publisher | PeerJ Inc. |
| record_format | Article |
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| spelling | doaj.art-fe0c2f3a9f3147b385d6f25da4619bf72023-12-03T09:46:15ZengPeerJ Inc.PeerJ2167-83592015-05-013e96610.7717/peerj.966966Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channelsAY Al-Brakati0T Kamishima1C Dart2JM Quayle3Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UKDepartment of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UKDepartment of Biochemistry and Cell Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, UKDepartment of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UKBackground and Purpose. Caveolae act as signalling hubs in endothelial and smooth muscle cells. Caveolar disruption by the membrane cholesterol depleting agent methyl-β-cyclodextrin (M-β-CD) has various functional effects on arteries including (i) impairment of endothelium-dependent relaxation, and (ii) alteration of smooth muscle cell (SMC) contraction independently of the endothelium. The aim of this study was to explore the effects of M-β-CD on rat femoral arteries.Methods. Isometric force was measured in rat femoral arteries stimulated to contract with a solution containing 20 mM K+ and 200 nM Bay K 8644 (20 K/Bay K) or with one containing 80 mM K+(80 K).Results. Incubation of arteries with M-β-CD (5 mM, 60 min) increased force in response to 20 K/Bay K but not that induced by 80 K. Application of cholesterol saturated M-β-CD (Ch-MCD, 5 mM, 50 min) reversed the effects of M-β-CD. After mechanical removal of endothelial cells M-β-CD caused only a small enhancement of contractions to 20 K/Bay K. This result suggests M-β-CD acts via altering release of an endothelial-derived vasodilator or vasoconstrictor. When nitric oxide synthase was blocked by pre-incubation of arteries with L-NAME (250 µM) the contraction of arteries to 20 K/Bay K was enhanced, and this effect was abolished by pre-treatment with M-β-CD. This suggests M-β-CD is inhibiting endothelial NO release. Inhibition of large conductance voltage- and Ca2+-activated (BKCa) channels with 2 mM TEA+ or 100 nM Iberiotoxin (IbTX) enhanced 20 K/Bay K contractions. L-NAME attenuated the contractile effect of IbTX, as did endothelial removal.Conclusions. Our results suggest caveolar disruption results in decreased release of endothelial-derived nitric oxide in rat femoral artery, resulting in a reduced contribution of BKCa channels to the smooth muscle cell membrane potential, causing depolarisation and contraction.https://peerj.com/articles/966.pdfEndotheliumVascular biologyCaveolaeSmooth muscleMembrane potentialBKCa channel |
| spellingShingle | AY Al-Brakati T Kamishima C Dart JM Quayle Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels PeerJ Endothelium Vascular biology Caveolae Smooth muscle Membrane potential BKCa channel |
| title | Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels |
| title_full | Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels |
| title_fullStr | Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels |
| title_full_unstemmed | Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels |
| title_short | Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels |
| title_sort | caveolar disruption causes contraction of rat femoral arteries via reduced basal no release and subsequent closure of bkca channels |
| topic | Endothelium Vascular biology Caveolae Smooth muscle Membrane potential BKCa channel |
| url | https://peerj.com/articles/966.pdf |
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