Anesthesiology 2009; 111:1052– 64 Copyright © 2009, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Age-associated Changes in Cardiac Gene Expression after Preconditioning Lixin Liu, M.D., Ph.D.,* Jiang Zhu, M.D.,† Peter S. A. Glass, M.B., Ch.B.,‡ Peter R. Brink, Ph.D.,§ Ira J. Rampil, M.D., M.S., Mario J. Rebecchi, Ph.D.# Background: Cardiac protection afforded by ischemic pre- conditioning (IPC) and anesthetic preconditioning (APC) are significantly reduced in the senescent myocardium. The au- thors hypothesized that age would differentially modulate gene expression induced by IPC and APC in vivo. Methods: Affymetrix RAT EXON ST 1.0 gene chips (Af- fymetrix, Santa Clara, CA) were used to explore the transcrip- tional response to IPC and APC in Fisher 344 male rats (young, 3–5 months, and old, 20 –24 months, respectively). Both co- horts, young and old, were divided into three groups: (1) sham control, (2) IPC, and (3) APC. After a total of 90 min, the heart was removed, and the total RNA and protein were extracted. Results: Thirty-one transcripts were increased in the young animals subjected to IPC, particularly transcriptional regulators (Atf3, Egr-1, Btg2, Egr2), cytokines (interleukin 6, CSF1, Myd88), chemokines (Cxcl10, Ccl2, Ccl7), regulators of growth and inflam- mation (Reg3g, Hamp), remodeling and cell adhesion migration (Cyr61, Tfpi2, Timp1), regulators of apoptosis/cell death (Birc3, Arntl, Hamp, Phlda1), and cell cycle control/DNA repairs (Rrad, Gadd45b, Gadd45g). In contrast, only one transcript increased (Atf3) in the old animals subjected to IPC. No changes in gene expression were found in the young or the old animals subjected to APC. Conclusions: Early-phase IPC and APC induced different genomic responses. The absence of detectable changes associ- ated with early-phase APC suggests a posttranscriptional or posttranslational mechanism. The absence of a genomic re- sponse in the senescent myocardium (except for IPC-induced Atf3) could underlie the failure of IPC to provide any cardiac protective benefit to older animals. DESPITE reduced mortality rates during the past decade, ischemic heart disease remains a leading cause of death and disability. It is well known that cardiovascular morbidity and mortality increase with age and that cardiovascular diseases are the major cause of death in the population older than 65 years. 1 Clearly, improving our knowledge of ischemic injury and cardioprotective therapies in the senes- cent myocardium is of paramount importance. Structural changes (thickening of the left ventricular wall decreases in the number of myocytes, and left ventricle cavity size) and diastolic dysfunction are the most prominent signs of cardiac aging. 2 Biochemical changes in aging hearts include decreased rates of cal- cium sequestration, accumulation of collagen, enhanced production of stress-related substances (e.g., atrial natri- uretic peptide and opioids), increased expression of angiotensin II receptors, and desensitization of cardiac -adrenergic receptors. 3 These structural and biochemi- cal changes could have major implications in the age-re- lated decrease in cardiac tolerance to ischemia. Old hearts have demonstrated worsening of myocardial stunning, have decreased recoveries in hemodynamic and high-en- ergy phosphates, and have greater overall tissue damage after ischemic insult. 4 However, the regulatory mecha- nisms underlying these changes are not fully understood. Ischemic preconditioning (IPC) and anesthetic precon- ditioning (APC) both represent powerful means of attain- ing myocardial protection against prolonged ischemia. 5,6 The preconditioning stimuli exhibit “memory” charac- terized by early and late windows of protection. The classic early memory of ischemic preconditioning lasts 1–2 h in anesthetized animals. 7,8 However, the precon- ditioning stimulus further initiates and triggers a second, longer-lasting genomic response involving increased de novo protein synthesis of the translated gene products. This late preconditioning, or second window, is ob- served 12–24 h after the initial transient ischemic event and lasts for up to 72 h. 9 In previous studies, we and others have shown that the cardiac protection afforded by IPC or APC is absent in the senescent rat myocardium. 10,11 Previous work has also shown that gene expression is altered in the senes- cent myocardium following myocardial ischemia–reper- fusion after 24 h. 12 Whether this is true of early-phase IPC or APC has not been examined. To our knowledge, no previous study has examined early-phase preconditioning in young and senescent myocardium and compared its effects on gene expression in vivo. We hypothesized that (1) early-phase IPC and APC would affect myocardial gene expression patterns differently in young compared with older animals, and (2) IPC and APC in animals of similar age would induce expression of a common set of precondition- ing genes. To test these ideas, microarrays analysis was used to measure genome-wide changes in myocardium messenger RNA (mRNA) levels after IPC and APC in young and old animals in vivo. Materials and Methods All experimental procedures and protocols used in this investigation were reviewed and approved by the Ani- * Clinical Assistant Professor, † Postdoctoral Fellow, ‡ Professor and Chairman, # Associate Professor, Department of Anesthesiology, § Professor and Chairman, Physiology and Biophysics,  Professor, Departments of Anesthesiology and Neurological Surgery, Stony Brook University School of Medicine. Received from the Department of Anesthesiology, Stony Brook University School of Medicine, Stony Brook, New York. Submitted for publication April 17, 2009. Accepted for publication August 4, 2009. Supported by Foundation for Anesthesia Education and Research grant–Research Starter Grant (RSG)-02/15/ 07, Rochester, Minnesota. Address correspondence to Dr. Liu: Department of Anesthesiology, Stony Brook University School of Medicine, HSC L4 060, Stony Brook, New York 11794. lixliu@notes.cc.sunysb.edu. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. ANESTHESIOLOGY’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue. Anesthesiology, V 111, No 5, Nov 2009 1052 Downloaded from anesthesiology.pubs.asahq.org by guest on 06/13/2020