Xu D L, Martin P Y, St John J, Tsai P, Summer S N, Ohara M, Kim J K, Schrier R W
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA.
Am J Physiol. 1996 Dec;271(6 Pt 2):R1739-45. doi: 10.1152/ajpregu.1996.271.6.R1739.
Pregnancy is characterized by hemodynamic and body fluid alterations. Increased nitric oxide (NO) production has been suggested to play a role in the hemodynamic alterations of pregnancy and has also been reported to increase arginine vasopressin (AVP) release. We therefore hypothesized that gestation could increase both NO synthase (NOS) constitutive isoforms, neuronal NOS and endothelial NOS, and thereby contribute to the hyposmolality and peripheral arterial vasodilation of pregnancy, respectively. The present study was therefore undertaken to examine the constitutive NOS isoforms in aortas, mesenteric arteries, and hypothalami of pregnant rats on day 20 of gestation compared with age-matched nonpregnant rats. Plasma AVP was determined by radioimmunoassay and hypothalamic mRNA AVP by solution hybridization assay. Hypothalamic neuronal NOS was assessed by Northern blot and Western blot; endothelial NOS was assessed by Western blot in arteries and hypothalamus. The results demonstrated that 1) plasma AVP and hypothalamic AVP mRNA are increased in pregnant rats (n = 8), 2) neuronal NOS protein and mRNA are increased in hypothalamus of pregnant rats (n = 4), and 3) endothelial NOS expression, as assessed by Western blot analysis, is increased in both conductance (aorta) as well as resistance (mesenteric) arteries of pregnant rats (n = 4). We conclude that both of the constitutive NOS isoforms are increased in pregnant rats, suggesting that the peripheral arterial vasodilation and hyposmolality of pregnancy could be mediated by these isoforms.
妊娠的特点是血液动力学和体液改变。一氧化氮（NO）生成增加被认为在妊娠血液动力学改变中起作用，并且据报道还会增加精氨酸加压素（AVP）的释放。因此，我们推测妊娠可能会增加两种一氧化氮合酶（NOS）组成型异构体，即神经元型NOS和内皮型NOS，从而分别导致妊娠时的低渗状态和外周动脉血管舒张。因此，本研究旨在检查妊娠第20天的妊娠大鼠与年龄匹配的未孕大鼠相比，其主动脉、肠系膜动脉和下丘脑中的组成型NOS异构体。通过放射免疫测定法测定血浆AVP，通过溶液杂交测定法测定下丘脑mRNA AVP。通过Northern印迹和Western印迹评估下丘脑神经元型NOS；通过Western印迹评估动脉和下丘脑中的内皮型NOS。结果表明：1）妊娠大鼠（n = 8）血浆AVP和下丘脑AVP mRNA增加；2）妊娠大鼠（n = 4）下丘脑神经元型NOS蛋白和mRNA增加；3）通过Western印迹分析评估，妊娠大鼠（n = 4）的传导性（主动脉）和阻力性（肠系膜）动脉中的内皮型NOS表达均增加。我们得出结论，妊娠大鼠中两种组成型NOS异构体均增加，这表明妊娠时的外周动脉血管舒张和低渗状态可能由这些异构体介导。
