AHEART June 47/6

Nekooeian, Ali Akbar, and Catherine C. Y. Pang. Effects of estrogen on venous function in rats with chronic heart failure. Am J Physiol Heart Circ Physiol 278: H1941– H1947, 2000.—The effect of 17b-estradiol on venous function was investigated in ovariectomized rats with heart failure. Rats (50–60 days old) were ovariectomized and implanted with 60-day-release pellets that contain 17b-estradiol (1.5 mg) or vehicle. The left coronary artery was ligated 7 days later. Another group of ovariectomized rats was given vehicle pellets and then a sham operation was performed. The rats were studied while under pentobarbital anesthesia at 7 wk after ligation. Ligated rats, relative to sham groups, had lower mean arterial pressure (MAP, 234 mmHg) and cardiac output (CO, 238%); higher arterial resistance (RA, 112%) and venous resistance (RV, 1116%); mean circulatory filling pressure (MCFP, 140%) and left ventricular end-diastolic pressure (LVEDP, 111 mmHg); and similar cardiovascular responses to norepinephrine (NE). Treatment of ligated rats with 17b-estradiol increased CO (116%); reduced RA (216%), RV (235%), MCFP (223%), and LVEDP (23 mmHg); and augmented MAP, RV, and MCFP responses to NE. Therefore, 17b-estradiol reduced MCFP, and this reduced preload (LVEDP). 17b-Estradiol decreased RV, which, along with decreased RA (afterload), led to an increase in CO. 17bEstradiol likely augmented vasoconstriction to NE through an improvement on the cardiovascular status.