High-dose folic acid pretreatment blunts cardiac dysfunction during ischemia coupled to maintenance of high-energy phosphates and reduces postreperfusion injury.
BACKGROUND
The B vitamin folic acid (FA) is important to mitochondrial protein and nucleic acid synthesis, is an antioxidant, and enhances nitric oxide synthase activity. Here, we tested whether FA reduces myocardial ischemic dysfunction and postreperfusion injury.


RESULTS
Wistar rats were pretreated with either FA (10 mg/d) or placebo for 1 week and then underwent in vivo transient left coronary artery occlusion for 30 minutes with or without 90 minutes of reperfusion (total n=131; subgroups used for various analyses). FA (4.5x10(-6) mol/L i.c.) pretreatment and global ischemia/reperfusion (30 minutes/30 minutes) also were performed in vitro (n=28). After 30 minutes of ischemia, global function declined more in controls than in FA-pretreated rats (Delta dP/dtmax, -878+/-586 versus -1956+/-351 mm Hg/s placebo; P=0.03), and regional thickening was better preserved (37.3+/-5.3% versus 5.1+/-0.6% placebo; P=0.004). Anterior wall perfusion fell similarly (-78.4+/-9.3% versus -71.2+/-13.8% placebo at 30 minutes), yet myocardial high-energy phosphates ATP and ADP reduced by ischemia in controls were better preserved by FA pretreatment (ATP: control, 2740+/-58 nmol/g; ischemia, 947+/-55 nmol/g; ischemia plus FA, 1332+/-101 nmol/g; P=0.02). Basal oxypurines (xanthine, hypoxanthine, and urate) rose with FA pretreatment but increased less during ischemia than in controls. Ischemic superoxide generation declined (3124+/-280 cpm/mg FA versus 5898+/-474 cpm/mg placebo; P=0.001). After reperfusion, FA-treated hearts had smaller infarcts (3.8+/-1.2% versus 60.3+/-4.1% placebo area at risk; P<0.002) and less contraction band necrosis, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positivity, superoxide, and nitric oxide synthase uncoupling. Infarct size declined similarly with 1 mg/d FA.


CONCLUSIONS
FA pretreatment blunts myocardial dysfunction during ischemia and ameliorates postreperfusion injury. This is coupled to preservation of high-energy phosphates, reducing subsequent reactive oxygen species generation, eNOS-uncoupling, and postreperfusion cell death.
Moens
An L
AL
Johns Hopkins Medical Institutions, Division of Cardiology, Baltimore, MD 21205, USA.
Champion
Hunter C
HC
Claeys
Marc J
MJ
Tavazzi
Barbara
B
Kaminski
Pawel M
PM
Wolin
Michael S
MS
Borgonjon
Dirk J
DJ
Van Nassauw
Luc
L
Haile
Azeb
A
Zviman
Muz
M
Bedja
Djahida
D
Wuyts
Floris L
FL
Elsaesser
Rebecca S
RS
Cos
Paul
P
Gabrielson
Kathy L
KL
Lazzarino
Giuseppe
G
Paolocci
Nazareno
N
Timmermans
Jean-Pierre
JP
Vrints
Christiaan J
CJ
Kass
David A
DA
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D054059:Coronary Occlusion / Q000188:drug therapy* / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005492:Folic Acid / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D020138:Hyperhomocysteinemia / Q000188:drug therapy; D009203:Myocardial Infarction / Q000209:etiology / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress / Q000187:drug effects; D011292:Premedication; D011355:Prodrugs / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011687:Purines / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism
D002316:Cardiotonic Agents; D011355:Prodrugs; D011687:Purines; D013481:Superoxides; D009569:Nitric Oxide; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005492:Folic Acid; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat