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Stroethoff M, Behmenburg F, Meierkord S, Bunte S, Mayer F, Mathes A, Heinen A, Hollmann MW, Huhn R. Cardioprotective Properties of Omecamtiv Mecarbil against Ischemia and Reperfusion Injury. J Clin Med 2019; 8:jcm8030375. [PMID: 30889854 PMCID: PMC6463149 DOI: 10.3390/jcm8030375] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/09/2019] [Accepted: 03/13/2019] [Indexed: 01/14/2023] Open
Abstract
Omecamtiv mecarbil (OM) is a first-in-class myosin activator. It was developed as a new inotropic therapy option for heart failure and is currently the object of a phase 3 clinical trial program. OM activates ryanodine receptors, which were shown to be involved in cardioprotection induced by conditioning strategies. We hypothesize that OM exerts a concentration-dependent cardioprotective effect through pre- and postconditioning. Isolated male Wistar rat hearts underwent 33 min of global ischemia and 60 min of reperfusion. OM was administered in various concentrations (1, 3, 10, and 30 µM) over 10 min prior to ischemia. Based on these results, in subsequent experiments 3 and 10 µM OM were given over 10 min after ischemia. Infarct sizes were determined by TTC staining. In controls, the infarct size was 60% ± 10% and 59% ± 12%, respectively. Ten micromolar OM before ischemia reduced the infarct size to 33% ± 8%. The lower concentrations did not initiate cardioprotection, and the next highest concentration did not enhance the protective effect. Even if 10 μM OM was given in the early reperfusion phase, it significantly reduced the infarct size (31% ± 6%), whereas 3 μM OM did not trigger a protective effect (58% ± 15%). This study shows for the first time that OM induces cardioprotection by pre- and postconditioning with a binary phenomenon, which is either ineffective or has a maximal effect.
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Affiliation(s)
- Martin Stroethoff
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
| | - Friederike Behmenburg
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
| | - Simon Meierkord
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
| | - Sebastian Bunte
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
| | - Felix Mayer
- Department of Forensic Medicine, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
| | - Alexander Mathes
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Cologne, Kerpener Str. 62, 50937 Cologne, Germany.
| | - André Heinen
- Institute of Cardiovascular Physiology, Heinrich-Heine-University Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany.
| | - Markus W Hollmann
- Department of Anesthesiology, Amsterdam University Medical Center (AUMC), Location AMC, University of Amsterdam, Meiberdreef 9, 1100DD Amsterdam, The Netherlands.
| | - Ragnar Huhn
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
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Abstract
We studied the interactions between rods and L-cones in deuteranopic human observers by stimulating the photoreceptors independently. Thresholds were determined using a PEST procedure for different ratios of rod to L-cone modulation without modulating the S-cones. Modulation frequency was either 2 or 10 Hz and the retinal illuminance ranged from 4.7 to 470 td (10.9-1090 scot td). We measured at 2, 7.5 and 20 degrees retinal eccentricity. The threshold data could be described by a model based on a vector addition of responses originating in the rods and the L-cones. The relative strength of rod signals relative to the L-cone signals increased with increasing retinal eccentricity and decreasing retinal illuminance. At 20 degrees eccentricity, rod and cone signals were of about equal magnitude at retinal illuminances as high as 470 td. Temporal frequency did not have a large effect on the ratio of rod to L-cone signal strength.
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Affiliation(s)
- J Kremers
- Department of Experimental Ophthalmology, University Eye Hospital, Tübingen, Germany.
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Lang F, Busch GL, Zempel G, Ditlevsen J, Hoch M, Emerich U, Axel D, Fingerle J, Meierkord S, Apfel H. Ca2+ entry and vasoconstriction during osmotic swelling of vascular smooth muscle cells. Pflugers Arch 1995; 431:253-8. [PMID: 9026786 DOI: 10.1007/bf00410198] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Exposure of aortic strips from guinea-pigs to hypotonic extracellular fluid is followed by marked vasoconstriction, which is inhibited by D-600 (3 microM), a blocker of voltage-sensitive Ca2+ channels. Conventional electrophysiology, patch-clamp studies, pH determination with 2',7' bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF) and Ca2+ measurements with Fura-2 have been performed on smooth muscle cells cultured either from rat or human aorta to further elucidate the underlying mechanisms. Exposure of the cells to a 25% hypotonic extracellular fluid leads to a rapid and fully reversible depolarization, paralleled by an increase of the selectivity and conductance of the cell membrane to Cl-, an acidification of the cytoplasm and an increase of intracellular Ca2+ concentration ([Ca2+]i). The latter is inhibited by the Ca2+ channel blocker D-600 (1-3 microM). It is concluded that osmotic cell swelling leads to the activation of an anion channel. The subsequent depolarization of the cell membrane activates voltage-sensitive Ca2+ channels which increases [Ca2+]i, thus stimulating the contraction of vascular smooth muscle cells.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Calcium Channels/metabolism
- Cell Size/physiology
- Cells, Cultured
- Electrophysiology
- Fura-2
- Guinea Pigs
- Humans
- Hydrogen-Ion Concentration
- Hypotonic Solutions
- In Vitro Techniques
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Muscle Tonus/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Osmolar Concentration
- Patch-Clamp Techniques
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- F Lang
- Physiologisches Institut der Universität Tübingen, Germany
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