Estrogen appears to have a protective effect against hypertension. In a previous study, gonadectomized female spontaneously hypertensive rats (SHR) were shown to have blood pressures as elevated as those of male SHR and higher than those of intact females. In addition, gonadectomized female SHR and male SHR had higher arterial muscle myosin light chain (MLC20) phosphorylation levels during maximum activation than did intact females. The purpose of this study was to determine if estrogen has an acute, direct effect on arterial muscle contraction. Caudal arterial muscle strips were dissected from mate Sprague-Dawley rats, placed in muscle baths and attached to force transducers. Muscle strips were contracted with 120 mM KC1 to establish maximum isometric force development (P0). Muscle baths were washed and the strips relaxed. Some strips were exposed to 17β-estradiol (10-9 or 10-7M). Other strips were contracted with a half-maximal dose of either KCl or norepinephrine (NE), and then exposed to 17β-estradiol during the plateau of the submaximal contractions. Peak responses were measured and normalized to % 0.5 P0. Exogenously applied 17 β-estradiol had no effect alone nor on the magnitude of responses to either KC1 or NE . Therefore, the protective effect of estrogen in hypertension may be due to a direct effect on muscle shortening or may be due to an indirect effect and/or more chronic effect on arterial muscle contractility.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology