ROLE AND REGULATION OF NITRIC OXIDE IN THE UTERUS

一氧化氮--内皮舒张剂的化学特性 因子(EDRF)，是一种具有很强光滑性的生物信使分子 肌肉松弛活动。由于其极短的半衰期， 一氧化氮的作用本质上是自体和旁分泌的，而且是 通过激活一种可溶性鸟苷酸环化酶和 3‘，5’-环鸟苷一磷酸(CGMP)及其几种化合物的生成 NO直接介导的其他机制，即K/Ca开放 频道。一氧化氮合酶已被证明存在于几个 包括子宫在内的其他组织。子宫一氧化氮合酶 活动量在怀孕期间增加，在怀孕前减少 分娩。这项建议解决了一氧化氮在体内 在怀孕期间保持子宫静止。我们假设 一氧化氮是在子宫(子宫内膜和子宫肌层)产生的。 在子宫肌层局部，在子宫肌层中发挥重要的生理作用。 通过降低细胞内钙离子维持子宫静止 通过cGMP依赖和cGMP非依赖机制。我们进一步 假设一氧化氮合酶活性和质量增加 在怀孕期间由雌激素和黄体酮引起。 我们将通过以下具体目标来检验这些假设。1) 具体目标一：研究一氧化氮的作用及其机制 它调节子宫肌层的收缩能力；2)特定目标II：特征 怀孕绵羊子宫中一氧化氮合酶的活性； 特殊目标三：调查调节表达和 子宫肌层和子宫内膜型一氧化氮合酶活性的研究 子宫。 绵羊将被用来研究内源性一氧化氮在 妊娠期间子宫肌层收缩的调节。我们会研究 内源性一氧化氮产生变化对自发性的影响 催产素引起子宫肌层收缩。CGMP在人体内的浓度 在体内收缩能力研究期间获得的血浆，以及组织和 体外研究的孵育液，将用来确定是否有硝酸盐 氧化物对子宫的影响与这一秒的变化有关 信使。CGMP对NO影响的相对贡献将是 通过研究cGMP类似物和NO对体外培养的大鼠心脏功能的影响 松弛和细胞内钙。我们将研究雌激素的作用 和孕酮作为一氧化氮合酶的调节因子 用~(14)C标记底物和免疫印迹法检测特异酶活性 在子宫组织中。在对细胞的理解中获得的知识 一氧化氮对子宫肌层的作用及一氧化氮合酶的调节 活性和酶质量，将提供对机制的新见解 确保子宫肌层静止，直到分娩。

Nitric oxide, the chemical identity for endothelium derived relaxing factor (EDRF), is a biological messenger molecule with potent smooth muscle relaxant activity. Due to its extremely short half life, the effects of nitric oxide are auto- and paracrine in nature, and are mediated through the activation of a soluble guanylyl cyclase and the generation of 3',5'-cyclic guanosine monophosphate (cGMP) and several other mechanisms that are mediated directly by NO, i.e., opening of K/Ca channels. Nitric oxide synthase has been shown to be present in several other tissues including the uterus. Uterine nitric oxide synthase activity is increased during pregnancy, and decreases prior to parturition. This proposal addresses the role of nitric oxide in the maintenance of uterine quiescence during pregnancy. We hypothesize that nitric oxide is produced in the uterus (endometrium and myometrium), acts locally in myometrium, and plays an important physiological role in the maintenance of uterine quiescence by decreasing intracellular calcium through cGMP-dependent and cGMP-independent mechanisms. We further hypothesize that nitric oxide synthase activity and mass are increased during pregnancy by estrogen and progesterone. We will test these hypotheses through the following specific aims. 1) Specific Aim I: Study the role of Nitric Oxide and the mechanisms by which it modulates myometrial contractility; 2) Specific Aim II: Characterize nitric oxide synthase activity in the pregnant sheep uterus; and, 3) Special Aim III: Investigate the factors that regulate the expression and activity of myometrial and endometrial nitric oxide synthase in the uterus. Sheep will be used to study the role of endogenous nitric oxide in the regulation of myometrial contractility during pregnancy. We will study the effects of changing endogenous nitric oxide production on spontaneous and oxytocin induced myometrial contractility. Concentrations of cGMP in plasma obtained during the in vivo contractility studies, and tissue and incubation media of in vitro studies, will be used to determine if nitric oxide effects on the uterus are associated with changes in this second messenger. The relative contribution of cGMP to the effects of NO will be determined by studying the effects of cGMP analogs and NO on in vitro relaxation and intracellular calcium. We will study the roles of estrogen and progesterone as regulators of nitric oxide synthase by measuring specific enzyme activity using 14C-labelled substrate, and immunoblotting in uterine tissues. Knowledge gained in the understanding of the cellular events associated with NO actions on myometrium, and the regulation of NOS activity and enzyme mass, will provide new insight on the mechanisms that ensure myometrial quiescence until the time of parturition.