Transient and partial mitochondrial inhibition for the treatment of postresuscitation injury: getting it just right.
OBJECTIVE
Within minutes of reperfusing ischemic cardiomyocytes, oxidant stress dramatically increases and is associated with postresuscitation injury. Because mitochondria produce deleterious oxidants and useful metabolic substrates, utilization of electron transport chain inhibitors against reperfusion injury, though promising, must not overly compromise recovery of mitochondrial function. This study sought to further characterize the oxidant source at reperfusion and develop a strategy for therapeutic intervention by manipulation of dose, duration, and the degree of reversibility of mitochondrial inhibition.


METHODS
Comparative laboratory investigation.


METHODS
Laboratory of a research university.


METHODS
Embryonic chick cardiomyocytes.


METHODS
Synchronously contracting chick cardiomyocytes were exposed to 1 hr of simulated ischemia and 3 hrs of reperfusion and were monitored for cell viability (propidium iodide) and oxidant generation (dichlorofluorescein). Inhibitors were administered either all course or for the first 15 mins of reperfusion.


RESULTS
: Application of diethyldithiocarbamic acid, 2-anthracene-carboxylic acid (rhein tech), and alpha-nicotinamide adenine dinucleotide dehydrogenase (NADH) demonstrated attenuation of the oxidant burst. In addition, diethyldithiocarbamic acid (1 mM), rhein tech (0.1 microM), and alpha-NADH (20 microM) significantly attenuated cell death from a control of 49.7% +/- 6.7% to 15.7% +/- 4.7% (n = 5, p < .01), 26.1% +/- 4.1% (n = 5, p < .01), and 13.8% +/- 1.3% (n = 5, p < .001), respectively. All doses of stigmatellin attenuated reactive oxygen species, but only a 2-20 nM dose during the first 15 mins of reperfusion abrogated cell death from 53.8% +/- 3.5% to 10.8% +/- 2.9% (n = 5, p < .001). Increased doses and durations of stigmatellin abolished reactive oxygen species but augmented injury. Although rotenone (5 microM) attenuated reactive oxygen species, no dose or duration of exposure that ameliorated cell death was found.


CONCLUSIONS
Early events of reperfusion are marked by rapid mitochondrial oxidant generation and postresuscitation injury. Electron transport chain blockade provides an effective method of attenuating reactive oxygen species. However, inhibitor administration should be both transient and reversible to necessitate cardioprotection and successful metabolic recovery.
Anderson
Travis C
TC
Emergency Resuscitation Center, Sections of Emergency Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
Li
Chang-Qing
CQ
Shao
Zuo-Hui
ZH
Hoang
Truc
T
Chan
Kim Chai
KC
Hamann
Kimm J
KJ
Becker
Lance B
LB
Vanden Hoek
Terry L
TL
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002264:Carboxylic Acids / Q000494:pharmacology; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects; D002642:Chick Embryo; D004050:Ditiocarb / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004579:Electron Transport; D008929:Mitochondria, Heart / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000209:etiology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D009243:NAD / Q000494:pharmacology; D011090:Polyenes / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology
D000873:Anthracenes; D002264:Carboxylic Acids; D011090:Polyenes; D017382:Reactive Oxygen Species; D012402:Rotenone; D009243:NAD; C107996:anthracene-1-carboxylic acid; C041573:stigmatellin; D004050:Ditiocarb