Cerebrovascular and ventilatory responses to autonomic reflex stimulation in supine and upright postures in women throughout the menstrual cycle and men

众所周知，与男性相比，女性站立时的血压下降幅度更大(即立位压力)，从而导致晕厥或头晕和头晕的症状。尽管确切的原因尚不清楚，但男性和女性之间以及整个月经周期对应激源的不同心血管反应可能起到了作用。重要的是，呼吸、二氧化碳和氧气都可以影响心血管功能，但在直立姿势下，月经周期或药物雌激素和孕酮(如口服避孕药(OC))对这些测量的影响从未被调查过。

Women are known to have a greater drop in blood pressure upon standing (i.e. orthostatic stress) compared to men leading to fainting or symptoms of lightheadedness and dizziness. Although the exact reasons for this are unclear, different cardiovascular responses to stressors between men and women, and throughout the menstrual cycle, likely play a role. Importantly, breathing, CO2, and O2 each can impact cardiovascular function yet the influence of the menstrual cycle or pharmaceutical estrogen and progesterone (such as oral contraceptives (OC)) on these measurements during upright posture has never been investigated.