Department of Physiology, College of Health Sciences, University of Ilorin, P.M.B. 1515 Ilorin 240001, Nigeria.
Vascul Pharmacol. 2010 Jan-Feb;52(1-2):95-100. doi: 10.1016/j.vph.2009.12.003. Epub 2009 Dec 24.
Cardiovascular complications are the major clinical challenges among users of synthetic steroids in oral contraceptive (OC) formulations. Interventions that reduce blood volume and improve vasorelaxation have been shown to reduce hypertension and the associated risk factors. The aim of the present study was to investigate the influence of increasing dietary calcium from 0.9 to 3.0% on the development of OC-induced high blood pressure and associated changes in female Sprague-Dawley rats treated with a combination of OC steroids (1 microg ethinyl estradiol and 10 microg norgestrel; p.o.) daily for 10 weeks. Results showed that OC administration led to significant increases in blood pressure, blood volume and cardiac weight. Conversely, OC caused significant reductions in body weight, urinary excretion of water, plasma levels of calcium, 17beta-estradiol and progesterone. Increased dietary calcium attenuated the elevation in blood pressure induced by OC and abrogated the associated changes in blood volume, cardiac weight, plasma calcium and urinary excretion of water. The endothelium-dependent relaxation responses to acetylcholine and endothelium-independent relaxation responses to sodium nitroprusside in noradrenaline-precontracted aortic rings were not significantly different among the groups. The results indicate that increased calcium intake abrogated the development of high blood pressure and associated increased blood volume and cardiac weight during OC treatment. The beneficial effect of increased dietary calcium during OC use may be explained by improved diuretic and preserved vasorelaxant responses.
心血管并发症是口服避孕药（OC）制剂中合成类固醇使用者面临的主要临床挑战。已经证实，减少血容量和改善血管舒张的干预措施可以降低高血压和相关的危险因素。本研究的目的是探讨从 0.9%增加到 3.0%的膳食钙对口服避孕药诱导的高血压发展的影响，并研究其对接受 OC 类固醇（1 微克炔雌醇和 10 微克去氧孕烯；口服）联合治疗的雌性 Sprague-Dawley 大鼠的影响每日 10 周。结果表明，OC 给药导致血压、血容量和心脏重量显著增加。相反，OC 导致体重、尿液水排泄、血浆钙、17β-雌二醇和孕酮水平显著降低。增加膳食钙可减轻 OC 引起的血压升高，并消除血容量、心脏重量、血浆钙和尿液水排泄的相关变化。去甲肾上腺素预收缩的主动脉环对乙酰胆碱的内皮依赖性舒张反应和对硝普钠的内皮非依赖性舒张反应在各组之间无显著差异。结果表明，增加钙摄入可消除 OC 治疗期间高血压和相关的血容量增加和心脏重量增加的发生。OC 使用期间增加膳食钙的有益作用可能归因于改善的利尿和保留的血管舒张反应。
