Reactive Oxygen Species and Mitochondrial Adenosine Triphosphate-Regulated Potassium Channels Mediate Helium-Induced Preconditioning Against Myocardial Infarction In Vivo

Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
Journal of cardiothoracic and vascular anesthesia (Impact Factor: 1.46). 09/2008; 22(4):554-9. DOI: 10.1053/j.jvca.2008.04.005
Source: PubMed


Helium produces preconditioning by activating prosurvival kinases, but the roles of reactive oxygen species (ROS) or mitochondrial adenosine triphosphate-regulated potassium (K(ATP)) channels in this process are unknown. The authors tested the hypothesis that ROS and mitochondrial K(ATP) channels mediate helium-induced preconditioning in vivo.
A randomized, prospective study.
A university research laboratory.
Male New Zealand white rabbits.
Rabbits (n = 64) were instrumented for the measurement of systemic hemodynamics and subjected to a 30-minute left anterior descending coronary artery (LAD) occlusion and 3 hours of reperfusion. In separate experimental groups, rabbits (n = 7 or 8 per group) were randomly assigned to receive 0.9% saline (control) or 3 cycles of 70% helium-30% oxygen administered for 5 minutes interspersed with 5 minutes of an air-oxygen mixture before LAD occlusion with or without the ROS scavengers N-acetylcysteine (NAC; 150 mg/kg) or N-2 mercaptoproprionyl glycine (2-MPG; 75 mg/kg), or the mitochondrial K(ATP) antagonist 5-hydroxydecanoate (5-HD; 5 mg/kg). Statistical analysis of data was performed with analysis of variance for repeated measures followed by Bonferroni's modification of a Student t test.
The myocardial infarct size was determined by using triphenyltetrazolium chloride staining and presented as a percentage of the left ventricular area at risk. Helium significantly (p < 0.05) reduced infarct size (23 +/- 4% of the area at risk; mean +/- standard deviation) compared with control (46 +/- 3%). NAC, 2-MPG, and 5-HD did not affect irreversible ischemic injury when administered alone (49 +/- 5%, 45 +/- 6%, and 45 +/- 3%), but these drugs blocked reductions in infarct size produced by helium (45 +/- 4%, 45 +/- 2%, and 44 +/- 3%).
The results suggest that ROS and mitochondrial K(ATP) channels mediate helium-induced preconditioning in vivo.

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Available from: Dorothee Weihrauch, Oct 09, 2015
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    • "Helium is safe for use in clinical practice and diving because of its favourable characteristics and the lack of hemodynamic side effects. Recent experimental research has convincingly shown the protective properties of helium against ischemia in the heart [4] [5] [6] [7] [8] [9] [10] and the brain [11] [12] [13]. These organs can be protected against I/R injury by subjecting them to several short helium episodes according to a specific protocol, known as helium preconditioning (HPC) [4–10,13]. "
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    ABSTRACT: Background & aims: Hepatic ischemia and reperfusion (I/R) injury is a major complication of liver transplantation, hepatic resection and trauma. Helium preconditioning (HPC) exerts protection against ischemic stress. We investigated potential beneficial effects of HPC on I/R-induced liver injury and investigated mechanisms underlying HPC-induced protection. Methods: We employed a model of segmental warm hepatic I/R on BALB/c mice. Serum ALT was measured and livers were analysed by histology, RT-PCR and western blot. HPC was induced by inhalation of a 70% helium/30% oxygen mixture for three 5-min periods, interspersed with three 5-min washout periods by room air. We tested which component of HPC (the helium/air mixture inhalation, the air room gap, or the interaction between these two factors) is protective. Results: We found that HPC caused a significant increase in Akt phosphorylation in hepatocytes. The HPC-induced Akt phosphorylation resulted in decreased hepatocellular injury and improved survival rate of the treated animals. PI3K inhibitors abolished HPC induced effects. HPC-induced Akt phosphorylation affected expression of its downstream molecules. The effects of HPC on the PI3K/Akt pathway were attenuated by adenosine A2A receptor blockade, but could be re-established by PTEN inhibition. We demonstrated that the interaction of helium/air breathing and air gaps is responsible for the observed effects of HPC. Conclusions: HPC may be a promising strategy leading to a decrease in I/R induced liver injury in clinical settings. Additionally, the PI3K/Akt pathway plays an essential role in the protective effects of HPC in hepatic I/R injury.
    Journal of Hepatology 06/2014; 61(5). DOI:10.1016/j.jhep.2014.06.020 · 11.34 Impact Factor
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    • "Later, they found that Helium maintains intracellular acidosis during early reperfusion, which inhibits mitochondrial transition pore formation [34]. In subsequent studies, researchers found that reactive oxygen species (including nitric oxide) [35,36], mitochondrial adenosine triphosphate-regulated potassium channels, [37], and opioid receptors [38] were responsible for the cardio-protective effects induced by helium preconditioning. "
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    ABSTRACT: The noble gas helium has many applications owing to its distinct physical and chemical characteristics, namely: its low density, low solubility, and high thermal conductivity. Chiefly, the abundance of studies in medicine relating to helium are concentrated in its possibility of being used as an adjunct therapy in a number of respiratory ailments such as asthma exacerbation, COPD, ARDS, croup, and bronchiolitis. Helium gas, once believed to be biologically inert, has been recently shown to be beneficial in protecting the myocardium from ischemia by various mechanisms. Though neuroprotection of brain tissue has been documented, the mechanism by which it does so has yet to be made clear. Surgeons are exploring using helium instead of carbon dioxide to insufflate the abdomen of patients undergoing laparoscopic abdominal procedures due to its superiority in preventing respiratory acidosis in patients with comorbid conditions that cause carbon dioxide retention. Newly discovered applications in Pulmonary MRI radiology and imaging of organs in very fine detail using Helium Ion Microscopy has opened exciting new possibilities for the use of helium gas in technologically advanced fields of medicine.
    08/2013; 3(1):18. DOI:10.1186/2045-9912-3-18
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    • "For instance, hydrogen, the first element in periodic table, is a medical gas that is synthesized in fermentation of non-digestible carbohydrates in human cells [1-3], has a neuroprotective role following middle cerebral artery occlusion (MCAO) [4], neonatal HI [5,6] and newborn pig asphyxia models [1,7]. Helium which has the second highest prevalence in the universe [1] has therapeutic effects on arrthymia [8] and inflammation [9,10], and has myocardioprotective role [1,11]. Argon, another noble gas has been used as anesthetic and neuroprotective agent [12]. "
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    ABSTRACT: Xenon is a medical gas capable of establishing neuroprotection, inducing anesthesia as well as serving in modern laser technology and nuclear medicine as a contrast agent. In spite of its high cost, its lack of side effects, safe cardiovascular and organoprotective profile and effective neuroprotective role after hypoxic-ischemic injury (HI) favor its applications in clinics. Xenon performs its anesthetic and neuroprotective functions through binding to glycine site of glutamatergic N-methyl-D-aspartate (NMDA) receptor competitively and blocking it. This blockage inhibits the overstimulation of NMDA receptors, thus preventing their following downstream calcium accumulating cascades. Xenon is also used in combination therapies together with hypothermia or sevoflurane. The neuroprotective effects of xenon and hypothermia cooperate synergistically whether they are applied synchronously or asynchronously. Distinguishing properties of Xenon promise for innovations in medical gas field once further studies are fulfilled and Xenon's high cost is overcome.
    02/2013; 3(1):4. DOI:10.1186/2045-9912-3-4
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