title: AM₁-receptor-dependent protection by intermedin of human vascular and cardiac non-vascular cells from ischaemia-reperfusion injury.
abstract: Intermedin (IMD) protects rodent heart and vasculature from oxidative stress and ischaemia. Less is known about distribution of IMD and its receptors and the potential for similar protection in man. Expression of IMD and receptor components were studied in human aortic endothelium cells (HAECs), smooth muscle cells (HASMCs), cardiac microvascular endothelium cells (HMVECs) and fibroblasts (v-HCFs). Receptor subtype involvement in protection by IMD against injury by hydrogen peroxide (H₂O₂, 1 mmol l⁻¹) and simulated ischaemia and reperfusion were investigated using receptor component-specific siRNAs. IMD and CRLR, RAMP1, RAMP2 and RAMP3 were expressed in all cell types.When cells were treated with 1 nmol l⁻¹ IMD during exposure to 1 mmol l⁻¹ H₂O₂ for 4 h, viability was greater vs. H2O2 alone (P<0.05 for all cell types). Viabilities under 6 h simulated ischaemia differed (P<0.05) in the absence and presence of 1 nmol l⁻¹ IMD: HAECs 63% and 85%; HMVECs 51% and 68%; v-HCFs 42% and 96%. IMD 1 nmol l⁻¹ present throughout ischaemia (3 h) and reperfusion (1 h) attenuated injury (P<0.05): viabilities were 95%, 74% and 82% for HAECs, HMVECs and v-HCFs, respectively, relative to those in the absence of IMD (62%, 35%, 32%, respectively). When IMD 1 nmol l⁻¹ was present during reperfusion only, protection was still evident (P<0.05, 79%, 55%, 48%, respectively). Cytoskeletal disruption and protein carbonyl formation followed similar patterns. Pre-treatment (4 days) of HAECs with CRLR or RAMP2, but not RAMP1 or RAMP3, siRNAs abolished protection by IMD (1 nmol l⁻¹) against ischaemia-reperfusion injury. IMD protects human vascular and cardiac non-vascular cells from oxidative stress and ischaemia-reperfusion,predominantly via AM1 receptors.
authors.affiliation: Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, UK. d.bell@qub.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Bell
authors.forename: Malcolm
authors.initials: M
authors.lastname: Campbell
authors.forename: Matthew
authors.initials: M
authors.lastname: Ferguson
authors.forename: Leah
authors.initials: L
authors.lastname: Sayers
authors.forename: Liz
authors.initials: L
authors.lastname: Donaghy
authors.forename: Anna
authors.initials: A
authors.lastname: O'Regan
authors.forename: Victoria
authors.initials: V
authors.lastname: Jewhurst
authors.forename: Mark
authors.initials: M
authors.lastname: Harbinson
mesh_terms: D000328:Adult; D001011:Aorta / Q000166:cytology; D015740:Calcitonin Gene-Related Peptide / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology; D005347:Fibroblasts / Q000502:physiology; D006801:Humans; D009206:Myocardium / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000502:physiology; D036361:Peptide Hormones / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D058261:Receptor Activity-Modifying Proteins / Q000502:physiology; D058265:Receptors, Adrenomedullin / Q000502:physiology*; D015427:Reperfusion Injury / Q000503:physiopathology*; D014162:Transfection
chemical_list: C484330:ADM2 protein, human; D036361:Peptide Hormones; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D058261:Receptor Activity-Modifying Proteins; D058265:Receptors, Adrenomedullin; D015740:Calcitonin Gene-Related Peptide