Hyperpolarisation of rat mesenteric endothelial cells by ATP-sensitive K+ channel openers

White, Richard M.

doi:10.1016/s0014-2999(00)00271-5

Cited by 29 publications

(33 citation statements)

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“…31,32 Following technique validation, the role of MEGJs in EDHF dilation was probed. Agonist activation of endothelial cells in the mesenteric artery increases [Ca 2ϩ ] i 22,33 and stimulates hyperpolarization, 3,15,34,35 followed by hyperpolarization and relaxation in the adjacent smooth muscle. 36,37 The smooth muscle effects are suggested to reflect the action of a diffusible EDHF, possibly K ϩ , and the spread of hyperpolarization from the endothelium through MEGJs.…”

Section: Discussionmentioning

confidence: 99%

“…Endothelial cell hyperpolarization reflects the opening of Ca 2ϩ -activated K ϩ channels 22,34,35 amplified by K ϩ efflux through the inwardly rectifying K ϩ channels focused within the endothelium of the mesenteric artery. 40,41 Consequent extracellular K ϩ accumulation then stimulates smooth muscle hyperpolarization and relaxation by activating Na ϩ /K ϩ -ATPase.…”

Section: Discussionmentioning

confidence: 99%

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Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Mather

Dora

Sandow

et al. 2005

Circulation Research

163

208

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Abstract-In resistance arteries, spread of hyperpolarization from the endothelium to the adjacent smooth muscle is suggested to be a crucial component of dilation resulting from endothelium-derived hyperpolarizing factor (EDHF). To probe the role of endothelial gap junctions in EDHF-mediated dilation, we developed a method, which was originally used to load membrane impermeant molecules into cells in culture, to load connexin (Cx)-specific inhibitory molecules rapidly (Ϸ15 minutes) into endothelial cells within isolated, pressurized mesenteric arteries of the rat. Validation was achieved by luminally loading cell-impermeant fluorescent dyes selectively into virtually all the arterial endothelial cells, without affecting either tissue morphology or function. The endothelial monolayer served as an effective barrier, preventing macromolecules from entering the underlying smooth muscle cells. Using this technique, endothelial cell loading either with antibodies to the intracellular carboxyl-terminal region of Cx40 (residues 340 to 358) or mimetic peptide for the cytoplasmic loop (Cx40; residues 130 to 140) each markedly depressed EDHF-mediated dilation. In contrast, multiple antibodies directed against different intracellular regions of Cx37 and Cx43, and mimetic peptide for the intracellular loop region of Cx37, were each without effect. Furthermore, simultaneous intra-and extraluminal incubation of pressurized arteries with inhibitory peptides targeted against extracellular regions of endothelial cell Cxs ( 43 Gap 26, 40 Gap 27, and 37,43 Gap 27; 300 mol/L each) for 2 hours also failed to modify the EDHF response. High-resolution immunohistochemistry localized Cx40 to the end of endothelial cell projections at myoendothelial gap junctions. These data directly demonstrate a critical role for Cx40 in EDHF-mediated dilation of rat mesenteric arteries. Key Words: endothelium-derived hyperpolarizing factor Ⅲ myoendothelial gap junctions Ⅲ endothelium-dependent dilation Ⅲ acetylcholine Ⅲ connexin 40 I n arterioles and some arteries, gap junctions between endothelial and smooth muscle cells (myoendothelial gap junctions [MEGJs]) enable changes in membrane potential to spread over considerable distances and, as a consequence, regulate blood flow by coordinating diameter change through the microcirculation. 1-3 For example, injection of hyperpolarizing current into a single endothelial cell can evoke extensive relaxation involving many smooth muscle cells throughout an isolated arteriole. 4,5 An important aspect of this response is that MEGJs may provide a crucial route for endothelial cell hyperpolarization to spread radially to the adjacent smooth muscle and evoke the dilation attributed to endothelium-derived hyperpolarizing factor (EDHF). 6 -8 In many arteries, there is more than 1 underlying mechanism for endothelium-dependent hyperpolarization of smooth muscle cells. In the rat mesenteric artery, during submaximal contraction to phenylephrine (PE), EDHF dilation appears to reflect hyperpolarizing current spread thro...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Mather

Dora

Sandow

et al. 2005

Circulation Research

163

208

View full text Add to dashboard Cite

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“…That block of endothelial cell SK Ca channels, associated with U46619 stimulation, is selective is also supported by unaltered hyperpolarization to the BK Ca channel activator NS1619 and the K ATP channel activator levcromakalim after exposure to U46619. In the mesenteric artery, BK Ca and K ATP channels are restricted to the smooth muscle cells (Mistry & Garland, 1998a;White & Hiley, 2000), whereas the IK Ca channels are on the endothelial not the smooth muscle cells (Walker et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Thromboxane receptor stimulation associated with loss of SK_Ca activity and reduced EDHF responses in the rat isolated mesenteric artery

Crane

Garland

2004

British J Pharmacology

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1 The possibility that thromboxane (TXA 2 ) receptor stimulation causes differential block of the SK Ca and IK Ca channels which underlie EDHF-mediated vascular smooth muscle hyperpolarization and relaxation was investigated in the rat isolated mesenteric artery. 2 Acetylcholine (30 nM-3 mM ACh) or cyclopiazonic acid (10 mM CPA, SERCA inhibitor) were used to stimulate EDHF-evoked smooth muscle hyperpolarization. In each case, this led to maximal hyperpolarization of around 20 mV, which was sensitive to block with 50 nM apamin and abolished by repeated stimulation of mesenteric arteries with the thromboxane mimetic, U46619 (30 nM-0.1 mM), but not the a 1 -adrenoceptor agonist phenylephrine (PE). 3 The ability of U46619 to abolish EDHF-evoked smooth muscle hyperpolarization was prevented by prior exposure of mesenteric arteries to the TXA 2 receptor antagonist 1 mM SQ29548. 4 Similar-sized smooth muscle hyperpolarization evoked with the SK Ca activator 100 mM riluzole was also abolished by prior stimulation with U46619, while direct muscle hyperpolarization in response to either levcromakalim (1 mM, K ATP activator) or NS1619 (40 mM, BK Ca activator) was unaffected. 5 During smooth muscle contraction and depolarization to either PE or U46619, ACh evoked concentration-dependent hyperpolarization (to À67 mV) and complete relaxation. These responses were well maintained during repeated stimulation with PE, but with U46619 there was a progressive decline, so that during a third exposure to U46619 maximum hyperpolarization only reached -52 mV and relaxation was reduced by 20%. This relaxation could now be blocked with charybdotoxin alone. The latter responses could be mimicked with 300 mM 1-EBIO (IK Ca activator), an action not modified by exposure to U46619. 6 An early consequence of TXA 2 receptor stimulation is a reduction in the arterial hyperpolarization and relaxation attributed to EDHF. This effect appears to reflect a loss of SK Ca activity.

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“…By activating ATP-sensitive K + (KATP) channels, which are restricted to the smooth muscle in rat mesenteric arteries, 62,64 it has been demonstrated that the SMCs are not coupled sufficiently to allow spreading dilatation over long distances, 62 emphasizing the importance of the endothelium as the conduit for electrical coupling. 28,51,65,66 This research suggests that the mechanism leading to hyperpolarization is not crucial in determining spread, only in initiating cell-cell coupling.…”

Section: Conducted Hyperpolarizationmentioning

confidence: 99%

Coordination of Vasomotor Responses by the Endothelium

Dora

2010

Circ J

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Hyperpolarisation of rat mesenteric endothelial cells by ATP-sensitive K+ channel openers

Cited by 29 publications

References 28 publications

Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Thromboxane receptor stimulation associated with loss of SK_Ca activity and reduced EDHF responses in the rat isolated mesenteric artery

Coordination of Vasomotor Responses by the Endothelium

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Hyperpolarisation of rat mesenteric endothelial cells by ATP-sensitive K+ channel openers

Cited by 29 publications

References 28 publications

Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Rapid Endothelial Cell–Selective Loading of Connexin 40 Antibody Blocks Endothelium-Derived Hyperpolarizing Factor Dilation in Rat Small Mesenteric Arteries

Thromboxane receptor stimulation associated with loss of SKCa activity and reduced EDHF responses in the rat isolated mesenteric artery

Coordination of Vasomotor Responses by the Endothelium

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Thromboxane receptor stimulation associated with loss of SK_Ca activity and reduced EDHF responses in the rat isolated mesenteric artery