1
|
Flenner F, Friedrich FW, Ungeheuer N, Christ T, Geertz B, Reischmann S, Wagner S, Stathopoulou K, Söhren KD, Weinberger F, Schwedhelm E, Cuello F, Maier LS, Eschenhagen T, Carrier L. Ranolazine antagonizes catecholamine-induced dysfunction in isolated cardiomyocytes, but lacks long-term therapeutic effects in vivo in a mouse model of hypertrophic cardiomyopathy. Cardiovasc Res 2015; 109:90-102. [PMID: 26531128 DOI: 10.1093/cvr/cvv247] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 10/27/2015] [Indexed: 12/19/2022] Open
Abstract
AIMS Hypertrophic cardiomyopathy (HCM) is often accompanied by increased myofilament Ca(2+) sensitivity and diastolic dysfunction. Recent findings indicate increased late Na(+) current density in human HCM cardiomyocytes. Since ranolazine has the potential to decrease myofilament Ca(2+) sensitivity and late Na(+) current, we investigated its effects in an Mybpc3-targeted knock-in (KI) mouse model of HCM. METHODS AND RESULTS Unloaded sarcomere shortening and Ca(2+) transients were measured in KI and wild-type (WT) cardiomyocytes. Measurements were performed at baseline (1 Hz) and under increased workload (30 nM isoprenaline (ISO), 5 Hz) in the absence or presence of 10 µM ranolazine. KI myocytes showed shorter diastolic sarcomere length at baseline, stronger inotropic response to ISO, and drastic drop of diastolic sarcomere length under increased workload. Ranolazine attenuated ISO responses in WT and KI cells and prevented workload-induced diastolic failure in KI. Late Na(+) current density was diminished and insensitive to ranolazine in KI cardiomyocytes. Ca(2+) sensitivity of skinned KI trabeculae was slightly decreased by ranolazine. Phosphorylation analysis of cAMP-dependent protein kinase A-target proteins and ISO concentration-response measurements on muscle strips indicated antagonism at β-adrenoceptors with 10 µM ranolazine shifting the ISO response by 0.6 log units. Six-month treatment with ranolazine (plasma level >20 µM) demonstrated a β-blocking effect, but did not reverse cardiac hypertrophy or dysfunction in KI mice. CONCLUSION Ranolazine improved tolerance to high workload in mouse HCM cardiomyocytes, not by blocking late Na(+) current, but by antagonizing β-adrenergic stimulation and slightly desensitizing myofilaments to Ca(2+). This effect did not translate in therapeutic efficacy in vivo.
Collapse
Affiliation(s)
- Frederik Flenner
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Felix W Friedrich
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Nele Ungeheuer
- Clinic for Cardiology and Pneumology, Georg-August-University Göttingen, Göttingen, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Birgit Geertz
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Silke Reischmann
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Stefan Wagner
- Clinic for Cardiology and Pneumology, Georg-August-University Göttingen, Göttingen, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany Department for Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - Konstantina Stathopoulou
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Klaus-Dieter Söhren
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany
| | - Florian Weinberger
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Edzard Schwedhelm
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Friederike Cuello
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Lars S Maier
- Clinic for Cardiology and Pneumology, Georg-August-University Göttingen, Göttingen, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany Department for Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Lucie Carrier
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20246 Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| |
Collapse
|
2
|
Uhl S, Mathar I, Vennekens R, Freichel M. Adenylyl cyclase-mediated effects contribute to increased Isoprenaline-induced cardiac contractility in TRPM4-deficient mice. J Mol Cell Cardiol 2014; 74:307-17. [PMID: 24972051 DOI: 10.1016/j.yjmcc.2014.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 05/30/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
TRPM4 and TRPM5 proteins belong to the Transient Receptor Potential (TRP) ion channel family and form Ca(2+)-activated nonselective cation channels. Recently we showed a significant increase of Isoprenaline-induced inotropy in TRPM4-deficient (Trpm4(-/-)) mice. This is caused by increased Ca(2+) entry via L-type calcium channels due to faster action potential repolarization in Trpm4(-/-) ventricular myocytes [Mathar et al., 2013]. Here, we investigated the contribution of various steps of the β-adrenergic signalling cascade to the augmented positive inotropic response in the absence of TRPM4, and whether the closely related TRPM5 additively contributes to this process using TRPM4/TRPM5-double deficient (Trpm4/Trpm5((-/-)2)) mice. We performed contractility measurements on isolated papillary muscles from wild type, Trpm4(-/-) and Trpm4/Trpm5((-/-)2) mice. As shown in Trpm4(-/-) mice, Isoprenaline-induced inotropy in Trpm4/Trpm5((-/-)2) papillary muscles was significantly increased compared to wild type, whereas basal, frequency- and Ca(2+)-dependent contractility was unaltered. Equivalent to Isoprenaline, activation of adenylyl cyclase using Forskolin led to a significantly increased twitch force in Trpm4(-/-) heart preparations whereas the Isoprenaline-mediated increase in cAMP level was comparable to wild type mice. Notably, the positive inotropic response evoked by phosphodiesterase inhibition with 3-isobutyl-1-methylxanthine (IBMX) was unchanged between both genotypes. Furthermore, experiments performed with increasing concentrations of IBMX after prestimulation with Forskolin and vice versa did not provide evidence that the increased β-adrenergic positive inotropic response in TRPM4-deficient papillary muscles is due to differences in accumulation of cAMP. Compared to inhibition of phosphodiesterase, the rise of intracellular cAMP by activating adenylyl cyclase is accompanied by ATP breakdown. To test the relevance of TRPM4 during forced ATP consumption we measured contractility under ischemic conditions. Here, Trpm4(-/-) papillary muscles showed improved contractile function in comparison to wild type. Our results are consistent with the hypothesis that TRPM4 has a limiting effect on cardiac contractility specifically in ATP depleting conditions. The increased positive inotropic response in Trpm4(-/-) papillary muscles evoked by stimulation of adenylyl cyclase activity is not observed without active enhancement of ATP hydrolysis. Furthermore, the contractility of Trpm4(-/-) papillary muscles was also increased during ischemic simulation. These data underscore the potential of TRPM4 inactivation as an approach to increase inotropy in specific conditions associated with increased catecholamine levels, such as heart failure and ischemia.
Collapse
Affiliation(s)
- Sebastian Uhl
- Pharmakologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany
| | - Ilka Mathar
- Pharmakologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany; Laboratory of Ion Channel Research, Department of Molecular and Cellular Biology, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium
| | - Rudi Vennekens
- Laboratory of Ion Channel Research, Department of Molecular and Cellular Biology, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium
| | - Marc Freichel
- Pharmakologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany; Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
| |
Collapse
|