title: Endothelium-derived intermedin/adrenomedullin-2 protects human ventricular cardiomyocytes from ischaemia-reoxygenation injury predominantly via the AM₁ receptor.
abstract: Application of intermedin/adrenomedullin-2 (IMD/AM-2) protects cultured human cardiac vascular cells and fibroblasts from oxidative stress and simulated ischaemia-reoxygenation injury (I-R), predominantly via adrenomedullin AM1 receptor involvement; similar protection had not been investigated previously in human cardiomyocytes (HCM). Expression of IMD, AM and their receptor components was studied in HCM. Receptor subtype involvement in protection by exogenous IMD against injury by simulated I-R was investigated using receptor component-specific siRNAs. Direct protection by endogenous IMD against HCM injury, both as an autocrine factor produced in HCM themselves and as a paracrine factor released from HCMEC co-cultured with HCM, was investigated using peptide-specific siRNA for IMD. IMD, AM and their receptor components (CLR, RAMPs1-3) were expressed in HCM. IMD 1nmol L(-1), applied either throughout ischaemia (3h) and re-oxygenation (1h) or during re-oxygenation (1h) alone, attenuated HCM injury (P<0.05); cell viabilities were 59% and 61% respectively vs. 39% in absence of IMD. Cytoskeletal disruption, protein carbonyl formation and caspase activity followed similar patterns. Pre-treatment (4 days) of HCM with CLR and RAMP2 siRNAs attenuated (P<0.05) protection by exogenous IMD. Pre-treatment of HCMEC with IMD (and AM) siRNA augmented (P<0.05) I-R injury: cell viabilities were 22% (and 32%) vs. 39% untreated HCMEC. Pre-treatment of HCM with IMD (and AM) siRNA did not augment HCM injury: cell viabilities were 37% (and 39%) vs. 39% untreated HCM. Co-culture with HCMEC conferred protection from injury on HCM; such protection was attenuated when HCMEC were pre-treated with IMD (but not AM) siRNA before co-culture. Although IMD is present in HCM, IMD derived from HCMEC and acting in a paracrine manner, predominantly via AM1 receptors, makes a marked contribution to cardiomyocyte protection by the endogenous peptide against acute I-R injury.
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom. Electronic address: d.bell@qub.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Bell
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Campbell
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: McAleer
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Ferguson
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Liz
authors.initials: L
authors.lastname: Donaghy
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Harbinson
mesh_terms: D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000502:physiology*; D018384:Oxidative Stress; D019899:Paracrine Communication; D036361:Peptide Hormones / Q000502:physiology*; D065840:Protective Factors; D058265:Receptors, Adrenomedullin / Q000378:metabolism
chemical_list: C484330:ADM2 protein, human; D036361:Peptide Hormones; D058265:Receptors, Adrenomedullin
keywords: Adrenomedullin; Ischaemia; Oxidative stress; Peptide