Previously, we demonstrated that integrated muscle sympathetic nerve activity (MSNA) responses to acute chemoreflex stress were augmented during the early follicular (EF) phase of the menstrual cycle relative to both the midluteal (ML) phase and males. These differences were most pronounced in the amplitude component of MSNA, suggesting EF-driven increases in action potential (AP) recruitment in females. Therefore, we tested the hypothesis that neural recruitment, quantified as MSNA AP discharge patterns during acute chemoreflex stress, is potentiated during EF. We retrospectively analyzed MSNA data from 9 young males and 7 young females tested during the EF and ML phases at rest and during a voluntary end-inspiratory hypercapnic-hypoxic apnea. Sympathetic AP discharge patterns were analyzed using wavelet-based methodology. Apnea-driven increases in AP frequency and AP content per integrated burst were greater in EF relative to ML (APs/min: P = 0.02; APs/burst: P = 0.03) and to males (APs/min: P = 0.04; APs/burst: P = 0.02). The recruitment of new larger AP clusters was greater in EF than ML (P < 0.01) but not different from males (P = 0.50). Interestingly, we observed a positive association between the magnitude of change in the estrogen/progesterone ratio from EF to ML and the change in AP cluster recruitment, as both decreased from EF to ML (R² = 0.82; P < 0.01). This suggests that the enhanced progesterone dominance over estrogen during ML may blunt the recruitment of new larger APs. Overall, these data indicate that both sex and the menstrual cycle impact AP recruitment patterns in a manner which may be mediated, at least in part, by gonadal hormones.

之前，我们证明了在月经周期的早期卵泡（EF）阶段，肌肉交感神经活动（MSNA）对急性化学反射应激的综合反应增强相对于黄体中期 (ML) 期和男性。这些差异在 MSNA 的幅度部分中最为明显，表明 EF 驱动的女性动作电位 (AP) 募集增加。因此，我们测试了以下假设：神经募集（量化为急性化学反射应激期间的 MSNA AP 放电模式）在 EF 期间得到增强。我们回顾性分析了 9 名年轻男性和 7 名年轻女性在静息 EF 和 ML 阶段以及自愿吸气末高碳酸血症缺氧呼吸暂停期间测试的 MSNA 数据。使用基于小波的方法分析交感神经 AP 放电模式。相对于 ML，EF 中由呼吸暂停驱动的 AP 频率和每次集成爆发的 AP 含量增加更大（APs/min： P = 0.02；APs/burst：P = 0.03）和男性（APs/min：P  = 0.04；APs/burst：P = 0.02）。EF 中新的较大 AP 簇的招募量高于 ML ( P  < 0.01)，但与男性没有差异 ( P  = 0.50)。有趣的是，我们观察到从 EF 到 ML 的雌激素/孕激素比率的变化幅度与 AP 簇募集的变化之间存在正相关，因为两者从 EF 到 ML 均下降（R 2 = 0.82；P ^<  0.01 ） 。这表明在 ML 过程中黄体酮对雌激素的优势增强可能会阻碍新的较大 AP 的募集。总体而言，这些数据表明，性别和月经周期都以可能至少部分由性腺激素介导的方式影响 AP 募集模式。