Cardiovascular Research Advance Access [Accepted Manuscript] published online on January 24, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn016
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Cardiac remodeling hinders activation of cyclooxygenase-2, diminishing protection by delayed pharmacologic preconditioning: Role of HIF1
and CREB
1 Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland and Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
2 Institute of Laboratory Animal Sciences, University of Zurich, Zurich, Switzerland
3 Department of Radiation Oncology, University Hospital Zurich, Switzerland, Switzerland
4 Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
Correspondence to: Privatdozent Dr. Michael Zaugg, Cardiovascular Anesthesia Research Laboratory, Center of Clinical Research, Institute of Anesthesiology, E-HOF, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland, Phone: +41 44 255 46 00, Fax: +41 44 255 44 09, E-mail: michael.zaugg{at}usz.ch
Aims: We tested whether delayed pharmacologic preconditioning elicited by isoflurane is protective in infarct-remodeled hearts.
Methods: Male Wistar rats were treated with the preconditioning drug isoflurane 6 wks after permanent ligation of the left anterior descending coronary artery. Twenty-four and 48 h later, hearts were perfused on the Langendorff system and treated with cyclooxygenase-2 or 12-lipoxygenase inhibitors before exposure to 40 min of ischemia followed by 90 min of reperfusion. Infarct size was determined by triphenyltetrazolium chloride staining and lactate dehydrogenase release. Cyclooxygenase-2 expression and activity were measured by Western blotting and colorimetric assay. Nuclear translocation of cyclooxygenase-2-inducing transcription factors HIF1
, CREB, STAT3, and NF
B was determined.
Results: Post-infarct, remodeled hearts exhibit alterations in cellular signaling, time course and extent of isoflurane-induced late protection. While remodeled, preconditioned hearts exhibited protection exclusively at 24 h, healthy hearts showed sustained protection for up to 48 h, which correlated with cyclooxygenase-2 protein expression and enzymatic activity. The cyclooxygenase-2 inhibitors celecoxib and NS-398, but not the 12-lipoxygenase inhibitor cinnamyl-3,4-dihydroxycyanocinnamate, abolished delayed protection in both healthy and remodeled hearts, identifying cyclooxygenase-2 as a key mediator of late protection in both models. Isoflurane induced nuclear translocation of HIF1 in all hearts, but CREB was exclusively activated in healthy but not remodeled myocardium, which expressed higher levels of the CREB antagonist ICER. Delayed protection by isoflurane in remodeled hearts was more vulnerable to inhibition by celecoxib.
Conclusions: Isoflurane failed to mobilize cyclooxygenase-2-inducing CREB in ICER-overexpressing, remodeled hearts, which was associated with a shortening of the second window of protection.
KEYWORDS Remodeling; Preconditioning; Ischemia/Reperfusion; Cyclooxygenase; NSAIDs
Time for primary review: 20
* Both authors equally contributed to this work
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