title: Effects of short-term administration of estradiol on reperfusion arrhythmias in rats of different ages.
abstract: Little is known about age-related differences in short-term effects of estradiol on ischemia-reperfusion (I/R) insults. The present study was designed to evaluate the effects of short-term treatment with estradiol on reperfusion arrhythmias in isolated hearts of 6-7-week-old and 12-14-month-old female rats. Wistar rats were sham-operated, ovariectomized and treated with vehicle or ovariectomized and treated with 17β-estradiol (E2; 5 µg·100 g-1·day-1) for 4 days. Hearts were perfused by the Langendorff technique. Reperfusion arrhythmias, i.e., ventricular tachycardia and/or ventricular fibrillation, were induced by 15 min of left coronary artery ligation and 30 min of reperfusion. The duration and incidence of I/R arrhythmias were significantly higher in young rats compared to middle-aged rats (arrhythmia severity index: 9.4 ± 1.0 vs 3.0 ± 0.3 arbitrary units, respectively, P < 0.05). In addition, middle-aged rats showed lower heart rate, systolic tension and coronary flow. Four-day E2 treatment caused an increase in uterine weight. Although E2 administration had no significant effect on the duration of I/R arrhythmias in middle-aged rats, it induced a marked reduction in the rhythm disturbances of young rats accompanied by a decrease in heart rate of isolated hearts. Also, this reduction was associated with an increase in QT interval. No significant changes were observed in the QT interval of middle-aged E2-treated rats. These data demonstrate that short-term estradiol treatment protects against I/R arrhythmias in hearts of young female rats. The anti-arrhythmogenic effect of estradiol might be related to a lengthening of the QT interval.
authors.affiliation: Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
authors.forename: S Q
authors.initials: SQ
authors.lastname: Savergnini
authors.forename: A M
authors.initials: AM
authors.lastname: Reis
authors.forename: R A S
authors.initials: RA
authors.lastname: Santos
authors.forename: P E B
authors.initials: PE
authors.lastname: Santos
authors.forename: A J
authors.initials: AJ
authors.lastname: Ferreira
authors.forename: A P
authors.initials: AP
authors.lastname: Almeida
mesh_terms: D000367:Age Factors; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000517:prevention & control*; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D004562:Electrocardiography; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D010052:Ovariectomy; D017208:Rats, Wistar; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D004958:Estradiol