Usselman Charlotte W, Wakefield Paige K, Skow Rachel J, Stickland Michael K, Chari Radha S, Julian Colleen G, Steinback Craig D, Davenport Margie H
From the Program for Pregnancy & Postpartum Health, Physical Activity and Diabetes Laboratory, Faculty of Physical Education & Recreation (C.W.U., P.K.W., R.J.S., C.D.S., M.H.D.), Alberta Diabetes Institute (C.W.U., P.K.W., R.J.S., C.D.S., M.H.D.), Women and Children's Health Research Institute (C.W.U., P.K.W., R.J.S., R.S.C., C.D.S., M.H.D.), Division of Pulmonary Medicine, Department of Medicine, Faculty of Medicine (M.K.S.), and Department of Obstetrics & Gynecology, Faculty of Medicine & Dentistry (R.S.C.), University of Alberta, Edmonton, AB, Canada; and Department of Medicine, University of Colorado Denver School of Medicine (C.G.J.).
Hypertension. 2015 Oct;66(4):858-64. doi: 10.1161/HYPERTENSIONAHA.115.05964. Epub 2015 Aug 10.
Baseline neurovascular transduction is reduced in normotensive pregnancy; however, little is known about changes to neurovascular transduction during periods of heightened sympathetic activation. We tested the hypothesis that, despite an exacerbated muscle sympathetic nerve activity (microneurography) response to cold pressor stimulation, the blunting of neurovascular transduction in normotensive pregnant women would result in similar changes in vascular resistance and mean arterial pressure (Finometer) relative to nonpregnant controls. Baseline neurovascular transduction was reduced in pregnant women relative to controls when expressed as the quotient of both total resistance and mean arterial pressure and sympathetic burst frequency (0.32±0.07 versus 0.58±0.16 mm Hg/L/min/bursts/min, P<0.001 and 2.4±0.7 versus 3.6±0.8 mm Hg/bursts/min, P=0.001). Sympathetic activation was greater across all 3 minutes of cold pressor stimulation in the pregnant women relative to the nonpregnant controls. Peak sympathoexcitation was also greater in pregnant than in nonpregnant women, whether expressed as sympathetic burst frequency (+17±13 versus +7±8 bursts/min, P=0.049), burst incidence (+17±9 versus +6±11 bursts/100 hb, P=0.03), or total activity (+950±660 versus +363±414 arbitrary units, P=0.04). However, neurovascular transduction during peak cold pressor-induced sympathoexcitation remained blunted in pregnant women (0.25±0.11 versus 0.45±0.08 mm Hg/L/min/bursts/min, P<0.001 and 1.9±1.0 versus 3.2±0.9 mm Hg/bursts/min, P=0.006). Therefore, mean arterial pressure (93±21 versus 99±6 mm Hg, P=0.4) and total peripheral resistance (12±3 versus 14±3 mm Hg/L/min) were not different between pregnant and nonpregnant women during peak sympathoexcitation. These data indicate that the third trimester of normotensive pregnancy is associated with reductions in neurovascular transduction, which result in the dissociation of sympathetic outflow from hemodynamic outcomes, even during cold pressor-induced sympathoexcitation.
正常血压妊娠时基线神经血管传导降低；然而，对于交感神经激活增强期间神经血管传导的变化知之甚少。我们检验了以下假设：尽管正常血压孕妇对冷加压刺激的肌肉交感神经活动（微神经ography）反应加剧，但相对于非孕对照，正常血压孕妇神经血管传导的减弱会导致血管阻力和平均动脉压（Finometer）出现类似变化。当以总阻力、平均动脉压与交感神经爆发频率的商表示时，孕妇的基线神经血管传导相对于对照降低（0.32±0.07对0.58±0.16毫米汞柱/升/分钟/爆发/分钟，P<0.001；2.4±0.7对3.6±0.8毫米汞柱/爆发/分钟，P=0.001）。在冷加压刺激的所有3分钟内，孕妇的交感神经激活相对于非孕对照更强。无论是以交感神经爆发频率（+17±13对+7±8爆发/分钟，P=0.049）、爆发发生率（+17±9对+6±11爆发/100次心跳，P=0.03）还是总活动（+950±660对+363±414任意单位，P=0.04）表示，孕妇的交感神经兴奋峰值也高于非孕女性。然而，冷加压诱导的交感神经兴奋峰值期间，孕妇的神经血管传导仍减弱（0.25±0.11对0.45±0.08毫米汞柱/升/分钟/爆发/分钟，P<0.001；1.9±1.0对3.2±0.9毫米汞柱/爆发/分钟，P=0.006）。因此，在交感神经兴奋峰值期间，孕妇与非孕女性的平均动脉压（93±21对99±6毫米汞柱，P=0.4）和总外周阻力（12±3对14±3毫米汞柱/升/分钟）无差异。这些数据表明，正常血压妊娠晚期与神经血管传导降低有关，这导致即使在冷加压诱导的交感神经兴奋期间，交感神经输出与血流动力学结果也相互分离。
