Experimental paperSoluble epoxide hydrolase gene deletion reduces survival after cardiac arrest and cardiopulmonary resuscitation☆
Introduction
The P450 epoxygenase pathway metabolizes arachidonic acid (AA) into biologically active eicosanoids referred to as epoxyeicosatrienoic acids (EETs).1 In the systemic circulation, EETs are primarily produced by vascular endothelium, where they serve as an endothelium-derived hyperpolarizing factor (EDHF).2 As such, EETs play an important role in regulating tissue perfusion in several organs, including heart, brain and kidney. However, EETs are short-lived, mainly due to metabolic conversion by soluble epoxide hydrolase (sEH) into dihydroxyeicosatrienoic acids (DHETs).3 Recent reports suggest that sEH inhibition is protective against cardiovascular disease, including hypertension-related end-organ damage.4, 5 In agreement with these reports, we have also shown that sEH inhibition is protective against stroke-related ischemic brain damage.6 Furthermore, sEH gene deletion in sEH knockout (sEHKO) mice renders these mice resistant to angiotensin II-induced hypertension.7 More recently, using an isolated perfused heart, Seubert et al. demonstrated that sEHKO mice exhibit improved ventricular function after myocardial ischemia.8 However, the impact of sEH gene deletion on survival and end-organ tissue damage in an in vivo model of whole-body ischemia remains unknown. Furthermore, vasodilation, while beneficial in focal ischemia, could be detrimental during cardiac resuscitation as it would lower the coronary perfusion pressure and critically compromise myocardial blood flow. Therefore, in the current study, we used an in vivo mouse model of cardiac arrest (CA) followed by cardiopulmonary resuscitation (CPR) to test the hypothesis that sEHKO mice demonstrate improved survival, renal functional recovery and attenuated pathologic ischemic renal damage. We here report the very significant, yet surprising, finding that sEH gene deletion, which protects against ischemic damage in an isolated heart preparation, impedes CPR and worsens survival after CA in vivo. This is a novel finding, with important clinical implications related to understanding mechanisms and developing new therapeutic agents for the prevention of and the facilitation of recovery from cardiac arrest.
Section snippets
Materials and methods
The study was conducted in accordance with the National Institute of Health guidelines for the care and use of animals in research and protocols were approved by the institutional animal care and use committee. The sEHKO strain was obtained from Dr. Frank Gonzalez at the National Institutes of Health, where it was originated. Gene disruption strategy and phenotype are described elsewhere.7 The strain has been backcrossed to C57Bl/6 for at least six generations; and therefore, homozygous sEHKO
Results
There were no significant differences between WT and sEHKO mice with regard to pre-arrest body weight, baseline or mean intra-arrest rectal temperature (Table 1, n = 15 per group). Both strains of mice were subjected to identical protocol of 10-min normothermic cardiac arrest, followed by cardiopulmonary resuscitation (CPR) under isoflurane anesthesia. In WT mice, restoration of spontaneous circulation (ROSC) was observed in all mice (15/15, 100%), which required 12.0 ± 0.5 mcg of epinephrine and
Discussion
The main finding of our study is that sEH gene deletion renders mice refractory to cardiopulmonary resuscitation (CPR) after cardiac arrest (CA). The sEHKO mice required significantly higher doses of epinephrine and longer CPR time, demonstrated delayed blood pressure recovery after CPR and suffered significantly higher mortality compared to wild-type control mice. Our findings suggest that sEH plays an important role in recovery from cardiac arrest, likely due to its EETs-metabolizing function.
Conflict of interest statement
None.
References (27)
Epoxygenase pathways of arachidonic acid metabolism
J Biol Chem
(2001)- et al.
Targeted disruption of soluble epoxide hydrolase reveals a role in blood pressure regulation
J Biol Chem
(2000) - et al.
Histopathological and behavioral characterization of a novel model of cardiac arrest and cardiopulmonary resuscitation in mice
J Neurosci Methods
(2004) - et al.
Compensatory mechanism for homeostatic blood pressure regulation in Ephx2 gene-disrupted mice
J Biol Chem
(2007) - et al.
Cytochrome P450 in neurological disease
Curr Drug Metab
(2004) - et al.
Identification of epoxyeicosatrienoic acids as endothelium-derived hyperpolarizing factors
Circ Res
(1996) - et al.
Soluble epoxide hydrolase inhibition protects the kidney from hypertension-induced damage
J Am Soc Nephrol
(2004) - et al.
An epoxide hydrolase inhibitor, 12-(3-adamantan-1-yl-ureido)dodecanoic acid (AUDA), reduces ischemic cerebral infarct size in stroke-prone spontaneously hypertensive rats
J Cardiovasc Pharmacol
(2005) - Zhang W, Koerner IP, Noppens R, et al. Soluble epoxide hydrolase: a novel therapeutic target in stroke. J Cereb Blood...
- et al.
Role of soluble epoxide hydrolase in postischemic recovery of heart contractile function
Circ Res
(2006)
Trends in the incidence of myocardial infarction and in mortality due to coronary heart disease, 1987–1994
N Engl J Med
Acute renal failure after whole body ischemia is characterized by inflammation and T cell-mediated injury
Am J Physiol Renal Physiol
Animal models of focal and global cerebral ischemia
ILAR J
Cited by (54)
Prospective for cytochrome P450 epoxygenase cardiovascular and renal therapeutics
2018, Pharmacology and TherapeuticsCitation Excerpt :Vascular actions on the pulmonary circulation to cause hypoxic vasoconstriction could lead to adverse events (Keserü et al., 2010; Pokreisz et al., 2006). Recovery from cardiopulmonary resuscitation is delayed in mice by sEH inhibitors or EPHX2 gene deletion (Hutchens et al., 2008). Increased generation of EETs is associated with pulmonary hypertension and epoxygenase inhibition reduces hypoxic pulmonary vasoconstriction (Keserü et al., 2010; Pokreisz et al., 2006).
Soluble epoxide hydrolase as a therapeutic target for pain, inflammatory and neurodegenerative diseases
2017, Pharmacology and TherapeuticsCitation Excerpt :Yet, there is some evidence PUFA diols are chemoattractant for monocytes (Kundu et al., 2013) and that linoleic diols specifically act as lipokines in the regulation of brown adipose tissue and thermogenesis (Lynes et al., 2017). There is no overt phenotype with the whole body knockout animals not subjected to physiologic stress (Spector & Kim, 2015), however, knockout mice had lower survival following ischemic events (Hutchens et al., 2008). In general, the biology of the knockout animals is mimicked by treatment with sEHI.
Pravastatin But Not Simvastatin Improves Survival and Neurofunctional Outcome After Cardiac Arrest and Cardiopulmonary Resuscitation
2017, JACC: Basic to Translational ScienceCitation Excerpt :Assessment was performed by an unbiased observer. Using the RotaRod test, mice were subjected to balancing on a rotating cylinder (12.5 revolutions/min) for 3 attempts of 300 s (900 s total), and the time until mice fell off the rod was recorded (19,20). Both the NeuroScore and RotaRod tests were applied on the day of CA/CPR (day 0, 1 h prior to CA/CPR) and on each of the following days until day 5 and then on days 7, 14, and 28 after CA/CPR.
Drug and Fatty Acid Cytochrome P450 Metabolism in Critical Care
2017, Drug Metabolism in DiseasesEpoxyeicosatrienoic acids and cardioprotection: The road to translation
2014, Journal of Molecular and Cellular CardiologyCitation Excerpt :For instance, as mentioned earlier, EETs have potent vasodilatory effects. Although this could be beneficial in hypertensive patients, delayed restoration of blood pressure may have played a role in the increased mortality of Ephx2−/− mice observed in a model of cardiac arrest-induced hypotension followed by cardiopulmonary resuscitation (CPR) [96]. The precise cause of death, including the direct role of EETs, remains unknown, but these data may have important clinical implications since cardiac arrest and hypotensive shock are complications of AMI.
- ☆
A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2007.06.031.