REGIONAL VARIATION IN RESISTANCE ARTERY DIAMETER RESPONSES TO ALPHA-ADRENERGIC STIMULATION DURING PREGNANCY
REGIONAL VARIATION IN RESISTANCE ARTERY DIAMETER RESPONSES TO ALPHA-ADRENERGIC STIMULATION DURING PREGNANCY
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DOI：
10.1152/ajpheart.1993.264.1.h78
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发表时间：
1993-01-01
影响因子：
--
通讯作者：
OSOL, G
中科院分区：
文献类型：
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作者：
DANGELO, G;OSOL, G
整个动物的升压反应在怀孕期间是钝的，然而，子宫动脉，矛盾的是，变得更加敏感的苯肾上腺素（PE）的收缩作用。本文的目的是研究1）妊娠期间与α-肾上腺素能刺激的剂量-管腔直径关系的区域变化（子宫动脉与肠系膜动脉），以及2）该途径的这些敏感性变化的选择性（PE与KCl）。在年龄匹配的未孕（非妊娠; NP）和晚期妊娠（LP;第19-20天）Sprague-Dawley大鼠的分离加压（50 mmHg）动脉节段中测量管腔直径。NP大鼠的子宫弓状动脉与肠系膜动脉对两种血管收缩剂的敏感性相同。然而，LP大鼠的弓形动脉对PE的敏感性是NP对照组的4.5倍（P < 0.01）。此外，直径曲线在[PE]大于或等于0.1 μ M时变得重叠，即使LP大鼠弓状动脉的初始直径显著更大（P < 0.001）。而LP大鼠肠系膜动脉对PE的敏感性降低3倍（P < 0.02），直径曲线呈平行的直线移动。妊娠不影响弓状动脉或肠系膜动脉对KCl去极化的敏感性。只有LP大鼠的弓状动脉管腔直径最大值[KCl]的减少百分比显著降低（P < 0.001）。因此，在妊娠期间，特异于α-肾上腺素能刺激的发散收缩反应发生在子宫与内脏循环的阻力动脉中。因此，在NP子宫动脉中低于阈值的PE浓度可引起管腔直径的较大变化，从而对妊娠状态下的子宫血管阻力具有显著影响。
Whole animal pressor responses are blunted during pregnancy; yet, uterine arteries, paradoxically, become significantly more sensitive to the constrictor effects of phenylephrine (PE). The objectives herein were to investigate 1) the regional variation (uterine vs. mesenteric arteries) in dose-lumen diameter relationship to alpha-adrenergic stimulation during pregnancy, and 2) the selectivity of these sensitivity shifts for this pathway (PE vs. KCl). Lumen diameter was measured in isolated, pressurized (50 mmHg) arterial segments from age-matched virgin (nonpregnant; NP) and late pregnant (LP; days 19-20) Sprague-Dawley rats. Uterine arcuate vs. mesenteric arteries from NP rats were equally sensitive to either vasoconstrictor. Arcuate arteries from LP rats, however, were 4.5-fold more sensitive to PE (P < 0.01) compared with those from NP controls. Furthermore, diameter curves became superimposed at [PE] greater-than-or-equal-to 0.1 muM, even though initial diameter of arcuate arteries from LP rats was significantly larger (P < 0.001). Conversely, mesenteric arteries from LP rats were threefold less sensitive to PE (P < 0.02), and the diameter curve displayed a corresponding parallel rightward shift. Pregnancy did not affect the sensitivity to KCl depolarization in either arcuate or mesenteric arteries. The percent reduction in lumen diameter to the maximum [KCl] was significantly decreased only in arcuate arteries from LP rats (P < 0.001). Thus, during pregnancy, divergent constrictor responses specific to alpha-adrenergic stimulation occur in resistance arteries from the uterine vs. splanchnic circulations. Consequently, concentrations of PE that are subthreshold in NP uterine arteries can elicit large changes in lumen diameter and thereby have a pronounced effect on uterine vascular resistance in the pregnant state.