Effects of hormone therapy and dietary soy on myocardial ischemia/reperfusion injury in ovariectomized atherosclerotic monkeys.
OBJECTIVE
Hormone therapy (HT) and dietary soy (Soy) inhibit myocardial ischemia/reperfusion (I/R) injury in nonatherosclerotic animals. The aim of this study was to determine their independent and interactive effects on I/R in monkeys previously fed an atherogenic diet for 15 months.


METHODS
Ovariectomized atherosclerotic monkeys (n = 40) were divided into one of four dietary treatment groups: (1) casein as the protein source, (2) casein and added HT (the equivalent of 5 mug ethinyl estradiol + 1 mg norethindrone acetate daily), (3) Soy protein providing 141 mg total isoflavones daily, or (4) Soy + HT. After 12 months monkeys were anesthetized, and their left anterior descending coronary artery was occluded for 1 hour and reperfused for 4 hours. Infarct size was the percentage of the area at risk not staining with triphenyltetrazolium chloride. Additional measures were myocardial blood flow, stroke volume, coronary output, myeloperoxidase, and malondialdehyde.


RESULTS
There was an interactive negative effect of HT + Soy to increase infarct size from approximately 30% (in other groups) to 55% (P = 0.0004). Additionally, there were negative main effects of Soy on blood flow, coronary output, and stroke volume during I/R (all P values <0.05). There were no effects of treatment on either myeloperoxidase or malondialdehyde.


CONCLUSIONS
Neither HT nor Soy had beneficial effects, whereas their combination had harmful effects, on myocardial I/R injury in monkeys with preexisting atherosclerosis. The mechanism of this negative interaction remains unclear but may relate to Soy's negative effects on hemodynamics.
Suparto
Irma H
IH
Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Williams
James Koudy
JK
Fox
Jamie L
JL
Yusuf
J Tuty L
JT
Sajuthi
Dondin
D
D000818:Animals; D003324:Coronary Artery Disease / Q000139:chemically induced / Q000517:prevention & control; D004036:Diet, Atherogenic; D019587:Dietary Supplements / Q000009:adverse effects*; D004195:Disease Models, Animal; D004347:Drug Interactions; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D007529:Isoflavones / Q000009:adverse effects; D008252:Macaca fascicularis; D008315:Malondialdehyde / Q000378:metabolism; D008593:Menopause / Q000187:drug effects*; D010052:Ovariectomy; D009195:Peroxidase / Q000187:drug effects / Q000378:metabolism; D015427:Reperfusion Injury / Q000503:physiopathology*; D030262:Soybean Proteins / Q000009:adverse effects*
D007529:Isoflavones; D030262:Soybean Proteins; D008315:Malondialdehyde; D009195:Peroxidase