title: Mechanisms of ischemic preconditioning effects on Ca(2+) paradox-induced changes in heart.
abstract: The effects of ischemic preconditioning (IP) on changes in cardiac performance and sarcoplasmic reticulum (SR) function due to Ca(2+) paradox were investigated. Isolated perfused hearts were subjected to IP (three cycles of 3-min ischemia and 3-min reperfusion) followed by Ca(2+)-free perfusion and reperfusion (Ca(2+) paradox). Perfusion of hearts with Ca(2+)-free medium for 5 min followed by reperfusion with Ca(2+)-containing medium for 30 min resulted in a dramatic decrease in the left ventricular (LV) developed pressure and a marked increase in LV end-diastolic pressure. Alterations in cardiac contractile activity due to Ca(2+) paradox were associated with depressed SR Ca(2+)-uptake, Ca(2+)-pump ATPase, and Ca(2+)-release activities as well as decreased SR protein contents for Ca(2+)-pump and Ca(2+) channels. All these changes due to Ca(2+) paradox were significantly prevented in hearts subjected to IP. The protective effects of IP on Ca(2+) paradox changes in cardiac contractile activity as well as SR Ca(2+)-pump and Ca(2+)-release activities were lost when the hearts were treated with 8-(p-sulfophenyl)-theophylline, an adenosine receptor antagonist; KN-93, a specific Ca(2+)/calmodulin-dependent protein kinase II (CaMK II) inhibitor; or chelerythrine chloride, a protein kinase C (PKC) inhibitor. These results indicate that IP rendered cardioprotection by preventing a depression in SR function in Ca(2+) paradox hearts. Furthermore, these beneficial effects of IP may partly be mediated by adenosine receptors, PKC, and CaMK II.
authors.affiliation: Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6.
authors.forename: K I
authors.initials: KI
authors.lastname: Kawabata
authors.forename: T
authors.initials: T
authors.lastname: Netticadan
authors.forename: M
authors.initials: M
authors.lastname: Osada
authors.forename: K
authors.initials: K
authors.lastname: Tamura
authors.forename: N S
authors.initials: NS
authors.lastname: Dhalla
mesh_terms: D000818:Animals; D002118:Calcium / Q000008:administration & dosage* / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D006321:Heart / Q000502:physiology*; D019194:Ischemic Preconditioning; D008297:Male; D009200:Myocardial Contraction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D016277:Ventricular Function, Left
chemical_list: D015220:Calcium Channels; D000252:Calcium-Transporting ATPases; D002118:Calcium