Glutathione reverses endothelial damage from peroxynitrite, the byproduct of nitric oxide degradation, in crystalloid cardioplegia.
BACKGROUND
NO has been advocated as an adjunct to cardioplegia solutions. However, NO undergoes a rapid biradical reaction with superoxide anions to produce peroxynitrite (ONOO(-)). ONOO(-) in crystalloid cardioplegia solution induces injury to coronary endothelium and to systolic function after cardioplegia and reperfusion. However, ONOO(-) may be degraded to less lethal or cardioprotective intermediates with glutathione (GSH) in reactions separate from its well known antioxidant effects. We hypothesized that GSH detoxifies ONOO(-) and reverses defects in endothelial function and systolic function when present in crystalloid cardioplegia.


RESULTS
In anesthetized dogs on cardiopulmonary bypass, a 45-minute period of global normothermic ischemia was followed by 60 minutes of intermittent cold crystalloid cardioplegia (Plegisol) and 2 hours of reperfusion. The cardioplegia solution contained 5 micromol/L authentic ONOO(-); catalase was included to attenuate the potential antioxidant effects of GSH and to unmask the effects on ONOO(-). In 1 group (CP+GSH, n=5), the cardioplegia contained 500 micromol/L GSH, whereas 1 group received crystalloid cardioplegia without GSH (CCP, n=6). There were no group differences in postcardioplegia left ventricular systolic function (end-systolic pressure-volume relation, impedance catheter: CCP 10.0+/-2.4 versus CP+GSH 10.6+/-1.3 mm Hg/mL) or diastolic chamber stiffness (ss-coefficient: CCP 0.35+/-0.2 versus CP+GSH 0.31+/-0.18). Myocardial neutrophil accumulation (myeloperoxidase activity) was attenuated in CP+GSH versus CCP (2.2+/-0.7 versus 5.4+/-1.2, P:<0.05). In postexperimental coronary arteries, maximal endothelium-dependent relaxation was greater in CP+GSH than in CCP (118+/-6% versus 92+/-5%, P:<0.05), with a smaller EC(50) value (-7. 10+/-0.05 versus -6.98+/-0.03, respectively, P:<0.05). Smooth muscle relaxation was complete in both groups. The adherence of neutrophils to postexperimental coronary arteries as a measure of endothelial function was less in CP+GSH than in CCP (98+/-18 versus 234+/-36 neutrophils/mm(2), P:<0.05). Nitrosoglutathione, a byproduct of the reaction between ONOO(-) and GSH, was greater in CP+GSH than in CCP (4.1+/-2.3 versus 0.4+/-0.2 microg/mL, P:<0.05).


CONCLUSIONS
GSH in crystalloid cardioplegia detoxifies ONOO(-) and forms cardioprotective nitrosoglutathione, resulting in attenuated neutrophil adherence and selective endothelial protection through the inhibition of neutrophil-mediated damage.
Nakamura
M
M
Emory University School of Medicine, Atlanta, GA, USA.
Thourani
V H
VH
Ronson
R S
RS
Velez
D A
DA
Ma
X L
XL
Katzmark
S
S
Robinson
J
J
Schmarkey
L S
LS
Zhao
Z Q
ZQ
Wang
N P
NP
Guyton
R A
RA
Vinten-Johansen
J
J
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D002122:Calcium Chloride / Q000378:metabolism / Q000494:pharmacology; D002315:Cardiopulmonary Bypass; D002448:Cell Adhesion / Q000187:drug effects; D003331:Coronary Vessels / Q000378:metabolism; D003402:Creatine Kinase / Q000097:blood; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006324:Heart Arrest, Induced / Q000379:methods*; D006439:Hemodynamics / Q000187:drug effects; D007036:Hypothermia, Induced; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009566:Nitrates / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009603:Nitroso Compounds; D009195:Peroxidase / Q000378:metabolism; D011189:Potassium Chloride / Q000378:metabolism / Q000494:pharmacology; D026422:S-Nitrosoglutathione; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects
D001639:Bicarbonates; D009566:Nitrates; D009603:Nitroso Compounds; C041711:St. Thomas' Hospital cardioplegic solution; C039642:peroxynitric acid; D009569:Nitric Oxide; D012965:Sodium Chloride; D026422:S-Nitrosoglutathione; D011189:Potassium Chloride; D009195:Peroxidase; D003402:Creatine Kinase; D005978:Glutathione; D008274:Magnesium; D002122:Calcium Chloride