title: Sarcolemmal cholesterol and caveolin-3 dependence of cardiac function, ischemic tolerance, and opioidergic cardioprotection.
abstract: Cholesterol-rich caveolar microdomains and associated caveolins influence sarcolemmal ion channel and receptor function and protective stress signaling. However, the importance of membrane cholesterol content to cardiovascular function and myocardial responses to ischemia-reperfusion (I/R) and cardioprotective stimuli are unclear. We assessed the effects of graded cholesterol depletion with methyl-β-cyclodextrin (MβCD) and lifelong knockout (KO) or overexpression (OE) of caveolin-3 (Cav-3) on cardiac function, I/R tolerance, and opioid receptor (OR)-mediated protection. Langendorff-perfused hearts from young male C57Bl/6 mice were untreated or treated with 0.02-1.0 mM MβCD for 25 min to deplete membrane cholesterol and disrupt caveolae. Hearts were subjected to 25-min ischemia/45-min reperfusion, and the cardioprotective effects of morphine applied either acutely or chronically [sustained ligand-activated preconditioning (SLP)] were assessed. MβCD concentration dependently reduced normoxic contractile function and postischemic outcomes in association with graded (10-30%) reductions in sarcolemmal cholesterol. Cardioprotection with acute morphine was abolished with ≥20 μM MβCD, whereas SLP was more robust and only inhibited with ≥200 μM MβCD. Deletion of Cav-3 also reduced, whereas Cav-3 OE improved, myocardial I/R tolerance. Protection via SLP remained equally effective in Cav-3 KO mice and was additive with innate protection arising with Cav-3 OE. These data reveal the membrane cholesterol dependence of normoxic myocardial and coronary function, I/R tolerance, and OR-mediated cardioprotection in murine hearts (all declining with cholesterol depletion). In contrast, baseline function appears insensitive to Cav-3, whereas cardiac I/R tolerance parallels Cav-3 expression. Novel SLP appears unique, being less sensitive to cholesterol depletion than acute OR protection and arising independently of Cav-3 expression.
authors: Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia;
authors: Louise E
authors: LE
authors: See Hoe
authors: Veterans Affairs San Diego Healthcare System, San Diego, California;
authors: Jan M
authors: JM
authors: Schilling
authors: Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia;
authors: Emiri
authors: E
authors: Tarbit
authors: Faculty of Health Sciences and Medicine, Bond University, Robina, Queensland, Australia; and.
authors: Can J
authors: CJ
authors: Kiessling
authors: Veterans Affairs San Diego Healthcare System, San Diego, California;
authors: Anna R
authors: AR
authors: Busija
authors: Veterans Affairs San Diego Healthcare System, San Diego, California;
authors: Ingrid R
authors: IR
authors: Niesman
authors: Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia;
authors: Eugene
authors: E
authors: Du Toit
authors: Faculty of Health Sciences and Medicine, Bond University, Robina, Queensland, Australia; and.
authors: Kevin J
authors: KJ
authors: Ashton
authors: Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, California.
authors: David M
authors: DM
authors: Roth
authors: Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia;
authors: John P
authors: JP
authors: Headrick
authors: Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, California.
authors: Hemal H
authors: HH
authors: Patel
authors: Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia; j.peart@griffith.edu.au.
authors: Jason N
authors: JN
authors: Peart
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism; D051244:Caveolin 3 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000172:deficiency / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009020:Morphine / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D012508:Sarcolemma / Q000187:drug effects* / Q000378:metabolism; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D002316:Cardiotonic Agents; C495548:Cav3 protein, mouse; D051244:Caveolin 3; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D009020:Morphine; D002784:Cholesterol
keywords: cardioprotection; caveolae; caveolin-3; cholesterol; contractility; ischemia-reperfusion; membrane microdomains; opioid receptors