Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BK<sub>Ca</sub> channels



Al-Brakati, AY, Kamishima, T, Dart, C ORCID: 0000-0002-3509-8349 and Quayle, JM ORCID: 0000-0003-2762-5011
(2015) Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BK<sub>Ca</sub> channels. PEERJ, 3 (5). e966-.

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Abstract

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 Ca(2+)-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.

Item Type: Article
Uncontrolled Keywords: Endothelium, Vascular biology, Caveolae, Smooth muscle, Membrane potential, BKCa channel, Femoral
Depositing User: Symplectic Admin
Date Deposited: 28 Jul 2017 15:10
Last Modified: 05 Oct 2023 09:26
DOI: 10.7717/peerj.966
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3008694