Estrogen replacement stimulates fatty acid oxidation and impairs post-ischemic recovery of hearts from ovariectomized female rats

• Published in: Canadian journal of physiology and pharmacology 2002-10, Vol.80 (10), p.1001-1007
• Main Authors: Grist, Mark, Wambolt, Richard B, Bondy, Gregory P, English, Dean R, Allard, Michael F
• Format: Article
• Language: English
• Subjects: Animals; Body Weight - drug effects; Cardiovascular disease; Estradiol - pharmacology; Estrogens; Estrogens - blood; Fatty acids; Fatty Acids - metabolism; Female; Health aspects; Heart - drug effects; Heart - physiopathology; Hormone replacement therapy; In Vitro Techniques; Myocardial Ischemia - metabolism; Myocardial Ischemia - physiopathology; Myocardial Reperfusion; Myocardium - metabolism; Organ Size - drug effects; Ovariectomy; Oxidation; Oxidation-Reduction; Physiological aspects; Rats; Rats, Sprague-Dawley; Women
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y02-131

Women less than 50 years of age, the majority of whom are likely premenopausal and exposed to estrogen, are at greater risk of a poor short-term recovery after myocardial ischemia than men and older women. Since estrogen enhances non-cardiac lipid utilization and increased lipid utilization is associated with poor post-ischemic heart function, we determined the effect of estrogen replacement on post-ischemic myocardial function and fatty acid oxidation. Female Sprague–Dawley rats, either intact (n = 15) or ovariectomized and treated with 17 β-estradiol (0.1 mg·kg –1 ·day –1 , s.c., n = 14) or corn oil vehicle (n = 16) for 5 weeks, were compared. Function and fatty acid oxidation of isolated working hearts perfused with 1.2 mM [9,10- 3 H]palmitate, 5.5 mM glucose, 0.5 mM lactate, and 100 mU/L insulin were measured before and after global no-flow ischemia. Only 36% of hearts from estrogen-treated rats recovered after ischemia compared with 56% from vehicle-treated rats (p > 0.05, not significant), while 93% of hearts from intact rats recovered (p < 0.05). Relative to pre-ischemic values, post-ischemic function of estrogen-treated hearts (26.3 ± 10.1%) was significantly lower than vehicle-treated hearts (53.4 ± 11.8%, p < 0.05) and hearts from intact rats (81.9 ± 7.0%, p < 0.05). Following ischemia, fatty acid oxidation was greater in estrogen-treated hearts than in the other groups. Thus, estrogen replacement stimulates fatty acid oxidation and impairs post-ischemic recovery of isolated working hearts from ovariectomized female rats.Key words: fatty acid oxidation, estrogen, ischemia, reperfusion.