Effects of oral contraceptives on sympathetic nerve activity during orthostatic stress in young, healthy women.
Effects of oral contraceptives on sympathetic nerve activity during orthostatic stress in young, healthy women.
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口服避孕药对年轻健康女性体位应激期间交感神经活动的影响。
DOI：
10.1152/ajpregu.00554.2009
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Schwartz,ChristopherE
中科院分区：
文献类型：
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作者：
Carter,JasonR;Klein,JennaC;Schwartz,ChristopherE
最近的研究报告称，月经周期会改变年轻、月经正常的女性对直立应激的交感神经反应。本研究的目的是确定口服避孕药 (OC) 是否会影响直立挑战期间的交感神经激活。基于服用 OC 的女性在“低激素”(LH) 阶段（即安慰剂药片）交感压力反射敏感性 (BRS) 增加的证据，我们假设在 LH 阶段肌肉交感神经活动 (MSNA) 对直立应激的反应增强。记录 12 名服用 OC 的健康女性（年龄 22 ± 1 岁）在进行性下半身负压（LBNP；-5、-10、-15、-20、-30、-40 mmHg；3 分钟/阶段）期间的 MSNA、平均动脉压 (MAP) 和心率 (HR)。通过检查舒张动脉压自发波动与 MSNA 之间的关系来评估交感 BRS。受试者接受两次检查：一次在 LH 阶段，一次在 LH 后约 3 周的“高激素”阶段（随机顺序）。静息 MSNA（10 ± 2 与 13 ± 2 次/分钟）、MAP（85 ± 3 与 84 ± 3 mmHg）和 HR（62 ± 2 与 65 ± 3 次/分钟）在不同阶段之间没有差异。 MSNA 和 HR 在进行性 LBNP 期间增加（P < 0.001），并且这些增加在各阶段之间相似。渐进式 LBNP 在任一阶段均不会改变 MAP。交感神经 BRS 在进行性 LBNP 期间增加，但这些反应在 LH 和高激素阶段之间没有差异。总之，我们的结果表明，口服避孕药不会改变年轻健康女性对直立挑战的心血管和交感神经反应。
Recent studies report that the menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women. The purpose of the present study was to determine whether oral contraceptives (OC) influence sympathetic neural activation during an orthostatic challenge. Based on evidence that sympathetic baroreflex sensitivity (BRS) is increased during the “low hormone” (LH) phase (i.e., placebo pills) in women taking OC, we hypothesized an augmented muscle sympathetic nerve activity (MSNA) response to orthostatic stress during the LH phase. MSNA, mean arterial pressure (MAP), and heart rate (HR) were recorded during progressive lower body negative pressure (LBNP; −5, −10, −15, −20, −30, −40 mmHg; 3 min/stage) in 12 healthy women taking OC (age 22 ± 1 years). Sympathetic BRS was assessed by examining relations between spontaneous fluctuations of diastolic arterial pressure and MSNA. Subjects were examined twice: once during LH phase and once ∼3 wk after LH during the “high hormone” phase (randomized order). Resting MSNA (10 ± 2 vs. 13 ± 2 bursts/min), MAP (85 ± 3 vs. 84 ± 3 mmHg), and HR (62 ± 2 vs. 65 ± 3 beats/min) were not different between phases. MSNA and HR increased during progressive LBNP (P< 0.001), and these increases were similar between phases. Progressive LBNP did not change MAP during either phase. Sympathetic BRS increased during progressive LBNP, but these responses were not different between LH and high hormone phases. In conclusion, our results demonstrate that OCs do not alter cardiovascular and sympathetic neural responses to an orthostatic challenge in young, healthy women.