Thromboxane induced‐vasoconstriction in coronary resistance arteries: Effects of age and ovarian hormone status

Abstract

Both age and ovarian hormones are known to influence coronary vascular function; however, little is known of the influence of ovarian hormones on coronary vascular reactivity in aged females. Therefore, the purpose of this study was to examine the effects of age and ovarian hormones on vasoconstrictor responses to U46619, a thromboxane A2 agonist. Coronary resistance arteries were isolated from the Left Anterior Descending (LAD) and Septal Artery distributions (SA) from young (6 mo), and old (24 mo) control (CON) and ovariectomized (OVEX) female Fischer-344 rats. In intact female rats, U46619-induced constriction was preserved with age in both LAD (6 mo: 31.6 ± 5.7 %; 24 mo: 32.7 ± 7.5%) and SA (6 mo: 27.6 ± 5.7 %; 24 mo: 20.0 ± 6.1%) regions. Ovariectomy increased U46619-induced constriction in resistance arteries from the LAD and SA regions in old but not young rats. Furthermore, the magnitude of the increase in constriction that occurred following ovariectomy in old rats was greater in LAD (OVEX: 75.0 ± 6.1% vs. 32.7%) resistance arteries as compared to SA (OVEX: 35.1 ± 6.6% vs. 20.0 ± 6.1%) resistance arteries. These data indicate that modulation of arteriolar function by ovarian hormones is heterogeneous in the coronary circulation and increases with advancing age. Funded by NIH grant HL077224.