title: Doxorubicin induced myocardial injury is exacerbated following ischaemic stress via opening of the mitochondrial permeability transition pore.
abstract: Chemotherapeutic agents such as doxorubicin are known to cause or exacerbate cardiovascular cell death when an underlying heart condition is present. However, the mechanism of doxorubicin-induced cardiotoxicity is unclear. Here we assess the cardiotoxic effects of doxorubicin in conditions of myocardial ischaemia reperfusion and the mechanistic basis of protection, in particular the role of the mitochondrial permeability transition pore (mPTP) in such protection. The effects of doxorubicin (1μM)±cyclosporine A (CsA, 0.2μM; inhibits mPTP) were investigated in isolated male Sprague-Dawley rats using Langendorff heart and papillary muscle contraction models subjected to simulated ischaemia and reperfusion injury. Isolated rat cardiac myocytes were used in an oxidative stress model to study the effects of drug treatment on mPTP by confocal microscopy. Western blot analysis evaluated the effects of drug treatment on p-Akt and p-Erk 1/2 levels. Langendorff and the isometric contraction models showed a detrimental effect of doxorubicin throughout reperfusion/reoxygenation as well as increased p-Akt and p-Erk levels. Interestingly, CsA not only reversed the detrimental effects of doxorubicin, but also reduced p-Akt and p-Erk levels. In the sustained oxidative stress assay to study mPTP opening, doxorubicin decreased the time taken to depolarization and hypercontracture, but these effects were delayed in the presence of CsA. Collectively, our data suggest for the first that doxorubicin exacerbates myocardial injury in an ischaemia reperfusion model. If the inhibition of mPTP ameliorates the cardiotoxic effects of doxorubicin, then more selective inhibitors of mPTP should be further investigated for their utility in patients receiving doxorubicin.
authors.affiliation: Department of Biomolecular and Sport Sciences, Coventry University, Cox Street, Coventry, CV1 5FB, UK.
authors.forename: M
authors.initials: M
authors.lastname: Gharanei
authors.forename: A
authors.initials: A
authors.lastname: Hussain
authors.forename: O
authors.initials: O
authors.lastname: Janneh
authors.forename: H L
authors.initials: HL
authors.lastname: Maddock
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D004317:Doxorubicin / Q000633:toxicity*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects*; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000150:complications*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000903:Antibiotics, Antineoplastic; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D004317:Doxorubicin; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases