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Cseplo P, Vamos Z, Ivic I, Torok O, Toth A, Koller A. The Beta-1-Receptor Blocker Nebivolol Elicits Dilation of Cerebral Arteries by Reducing Smooth Muscle [Ca2+]i. PLoS One 2016; 11:e0164010. [PMID: 27716772 PMCID: PMC5055296 DOI: 10.1371/journal.pone.0164010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 09/19/2016] [Indexed: 01/22/2023] Open
Abstract
Rationale Nebivolol is known to have beta-1 blocker activity, but it was also suggested that it elicits relaxation of the peripheral arteries in part via release of nitric oxide (NO). However, the effect of nebivolol on the vasomotor tone of cerebral arteries is still unclear. Objective To assess the effects of nebivolol on the diameter of isolated rat basilar arteries (BA) in control, in the presence of inhibitors of vasomotor signaling pathways of know action and hemolysed blood. Methods and Results Vasomotor responses were measured by videomicroscopy and the intracellular Ca2+ by the Fura-2 AM ratiometric method. Under control conditions, nebivolol elicited a substantial dilation of the BA (from 216±22 to 394±20 μm; p<0.05) in a concentration-dependent manner (10−7 to 10−4 M). The dilatation was significantly reduced by endothelium denudation or by L-NAME (inhibitor of NO synthase) or by SQ22536 (adenylyl cyclase blocker). Dilatation of BA was also affected by beta-2 receptor blockade with butoxamine, but not by the guanylate cyclase blocker ODQ. Interestingly, beta-1 blockade by atenolol inhibited nebivolol-induced dilation. Also, the BKCa channel blocker iberiotoxin and KCa channel inhibitor TEA significantly reduced nebivolol-induced dilation. Nebivolol significantly reduced smooth muscle Ca2+ level, which correlated with the increases in diameters and moreover it reversed the hemolysed blood-induced constriction of BA. Conclusions Nebivolol seems to have an important dilator effect in cerebral arteries, which is mediated via several vasomotor mechanisms, converging on the reduction of smooth muscle Ca2+ levels. As such, nebivolol may be effective to improve cerebral circulation in various diseased conditions, such as hemorrhage.
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Affiliation(s)
- Peter Cseplo
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Central Anesthesiology and Intensive Therapy, Petz Aladar County Teaching Hospital, Gyor, Hungary
| | - Zoltan Vamos
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Pecs, Medical School, Pecs, Hungary
| | - Ivan Ivic
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anatomy, University of Pecs, Medical School, Pecs, Hungary
| | - Orsolya Torok
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary
| | - Attila Toth
- Institute of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Akos Koller
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Neurosurgery, University of Pecs, Medical School, Pecs, Hungary.,Department of Physiology, New York Medical College, Valhalla, New York, United States of America.,Institute of Natural Sciences, University of Physical Education, Budapest, Hungary
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Ella SR, Yang Y, Clifford PS, Gulia J, Dora KA, Meininger GA, Davis MJ, Hill MA. Development of an image-based system for measurement of membrane potential, intracellular Ca(2+) and contraction in arteriolar smooth muscle cells. Microcirculation 2011; 17:629-40. [PMID: 21044217 DOI: 10.1111/j.1549-8719.2010.00059.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Changes in smooth muscle cell (SMC) membrane potential (Em) are critical to vasomotor responses. As a fluorescent indicator approach would lessen limitations of glass electrodes in contracting preparations, we aimed to develop a Forster (or fluorescence) resonance energy transfer (FRET)-based measurement for Em. METHODS The FRET pair used in this study (donor CC2-DMPE [excitation 405 nm] and acceptor DisBAC(4) (3)) provide rapid measurements at a sensitivity not achievable with many ratiometric indicators. The method also combined measurement of changes in Ca(2+) (i) using fluo-4 and excitation at 490 nm. RESULTS After establishing loading conditions, a linear relationship was demonstrated between Em and fluorescence signal in FRET dye-loaded HEK cells held under voltage clamp. Over the voltage range from -70 to +30 mV, slope (of FRET signal vs. voltage, m) = 0.49 ± 0.07, r(2) = 0.96 ± 0.025. Similar data were obtained in cerebral artery SMCs, slope (m) = 0.30 ± 0.02, r(2) = 0.98 ± 0.02. Change in FRET emission ratio over the holding potential of -70 to +30 mV was 41.7 ± 4.9% for HEK cells and 30.0 ± 2.3% for arterial SMCs. The FRET signal was also shown to be modulated by KCl-induced depolarization in a concentration-dependent manner. Further, in isolated arterial SMCs, KCl-induced depolarization (60 mM) measurements occurred with increased fluo-4 fluorescence emission (62 ± 9%) and contraction (-27 ± 4.2%). CONCLUSIONS The data support the FRET-based approach for measuring changes in Em in arterial SMCs. Further, image-based measurements of Em can be combined with analysis of temporal changes in Ca(2+) (i) and contraction.
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Affiliation(s)
- Srikanth R Ella
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
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Eichler I, Wibawa J, Grgic I, Knorr A, Brakemeier S, Pries AR, Hoyer J, Köhler R. Selective blockade of endothelial Ca2+-activated small- and intermediate-conductance K+-channels suppresses EDHF-mediated vasodilation. Br J Pharmacol 2003; 138:594-601. [PMID: 12598413 PMCID: PMC1573692 DOI: 10.1038/sj.bjp.0705075] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Activation of Ca(2+)-activated K(+)-channels (K(Ca)) has been suggested to play a key role in endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilation. However, due to the low selectivity of commonly used K(Ca)-channel blockers it is still elusive which endothelial K(Ca)-subtypes mediate hyperpolarization and thus initiate EDHF-mediated vasodilation. 2. Using the non-cytochrome P450 blocking clotrimazole-derivatives, 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) and 2-(2-chlorophenyl)-2,2-diphenylacetonitrile (TRAM-39) as highly selective IK1-inhibitors, we investigated the role of the intermediate-conductance K(Ca) (rIK1) in endothelial hyperpolarization and EDHF-mediated vasodilation. 3. Expression and function of rIK1 and small-conductance K(Ca) (rSK3) were demonstrated in situ in single endothelial cells of rat carotid arteries (CA). rIK1-currents were blocked by TRAM-34 or TRAM-39, while rSK3 was blocked by apamin. In current-clamp experiments, endothelial hyperpolarization in response to acetylcholine was abolished by the combination of apamin and TRAM-34. 4. In phenylephrine-preconstricted CA, acetylcholine-induced NO and prostacyclin-independent vasodilation was almost completely blocked by ChTX, CLT, TRAM-34, or TRAM-39 in combination with the SK3-blocker apamin. Apamin, TRAM-34, and CLT alone or sulphaphenzole, a blocker of the cytochrome P450 isoform 2C9, were ineffective in blocking the EDHF-response. 5. In experiments without blocking NO and prostacyclin synthesis, the combined blockade of SK3 and IK1 reduced endothelium-dependent vasodilation. 6. In conclusion, the use of selective IK1-inhibitors together with the SK3-blocker apamin revealed that activation of both K(Ca), rIK1 and rSK3 is crucial in mediating endothelial hyperpolarization and generation of the EDHF-signal while the cytochrome P450 pathway seems to play a minor or no role in rat CA.
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Affiliation(s)
- Ines Eichler
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Judith Wibawa
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Ivica Grgic
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Andrea Knorr
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Susanne Brakemeier
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Axel R Pries
- Institute of Physiology, Freie Universität, Berlin, Germany
| | - Joachim Hoyer
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
| | - Ralf Köhler
- Department of Nephrology, Benjamin Franklin Medical Center, Berlin, Germany
- Author for correspondence:
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