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A3273
October 13, 2014
1:00 PM - 3:00 PM
Room Hall B1-Area C
Effects of Epinephrine Exposure on Angiogenesis-Related Gene Expressions in Cultured Rat Cardiomyocytes
Henry Liu, M.D., Ming Chen, M.D., Ling Yu, M.D., Marcia B. Henry, Ph.D., Lisa Sangkum, M.D., Jiao Liu, M.D., Charles J. Fox, M.D., Alan D. Kaye, M.D., Ph.D., Frank A. Rosinia, M.D.
Tulane University Medical Center, New Orleans, Louisiana, United States
Introduction:

Epinephrine is often used in managing patients with low cardiac output syndrome. However, studies have shown epinephrine could lead to adverse clinical outcomes [1]. Angiogenesis is a process of neovascularization which may potentially revitalize some chronically ischemic myocardium. We hypothesized that epinephrine exposure may alter the angiogenesis-related gene expressions, which may contribute to the observed adverse clinical outcomes.

Methods:

Rat cardiomyocytes (H9C2) were inoculated at the concentration of 0.5M/ml and cultured at 37oC in DEME. The cells were allowed to settle down overnight and then exposed to epinephrine (1uM) for 48 hours. H9C2 cells without epinepherine served as controls. RNA was extracted from cultured cardiomyocytes for whole genome gene expression study. This array contains 41,000+ rat genes. cDNA was synthesized from RNA samples and used to synthesize fluorescent cRNA. Labeled cRNA samples were hybridized to the Whole Rat Genome Oligo Microarray slides. After hybridization, arrays were washed and scanned. These data were imported into GeneSpring software as 20 one-color arrays and normalized to the median per chip and the median value per gene across all arrays. Parameter data was added so that microarrays could be grouped by time and treatment. Guided workflow returned several gene lists. These were analyzed for significant Gene Ontology and pathway hits based on passed P value. Epinephrine-induced gene expressional changes (with P < 0.05) related to cardiac fibrosis were identified (Figure-1).

Results: Up-regulated genes included ANGPT2 (2.12 times) which encodes Angiopoietin-2, a natural antagonist for ANGPT1 and TIE, both are stimulants for angiogenesis. Down-regulated gene expressions included NRG1(-3.653 Times) which encodes Neuregulin1, a peptide essential for the development of heart [2]; SERPINE1 (-2.42 times) which encodes plasminogen activator inhibitor-1;and SMOC2 (-4.52 times) which encodes SPARC-related modular calcium-binding protein-2, a facilitator of angiogenesis [3].

Discussion: Our study indicated that exposure of cultured cardiomyocytes to epinephrine for 48 hours significantly alters angiogenesis-related gene expressions in cultured rat cardiomyocytes. These changes suggest epinephrine exposure may inhibit angiogenic process, which is harmful, especially in ischemic myocardium. Whether the epinephrine-induced gene expressions lead to the clinically observed long-term adverse outcomes in patients treated with epinephrine is not clear. Further studies are needed to illustrate the importance of these gene expressional changes.



References:

1. Mebazaa A, Parissis J, Porcher R, Gayat E, Nikolaou M, Boas FV, Delgado JF, Follath F.Short-term survival by treatment among patients hospitalized with acute heart failure: the global ALARM-HF registry using propensity scoring methods. Intensive Care Med. 2011 Feb; 37(2):290-301.

2. Hedhli N, Dobrucki LW, Kalinowski A, Zhuang ZW, Wu X, Russell RR 3rd, Sinusas AJ, Russell KS. Endothelial-derived neuregulin is an important mediator of ischaemia-induced angiogenesis and arteriogenesis. Cardiovasc Res. 2012 Mar 1;93(3):516-24.

3. Rocnik EF, Liu P, Sato K, Walsh K, Vaziri C. The Novel SPARC Family Member SMOC-2 Potentiates Angiogenic Growth Factor Activity. J Biol Chem. 2006 Aug 11; 281(32):22855-64.
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