PERMISSIVE ROLE OF PGI-2 IN NEWBORN CEREBRAL CIRCULATION

PGI-2 在新生儿脑循环中的许可作用

• 批准号: 2220719
• 负责人: CHARLES W. LEFFLER
• 金额: $ 21.05万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-08-16 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2220719
• 关键词: acid base balance; carbon dioxide tension; cyclic AMP; electron microscopy; fatty acid metabolism; hemodynamics; histopathology; hypercapnia; microcirculation; muscle function; newborn animals; prostacyclins; radioimmunoassay; radionuclides; radiotracer; receptor binding; respiratory gas level; statistical service /center; swine; vascular smooth muscle; vasodilatation

The research proposed is designed to address the unifying hypothesis that endothelial-derived prostacyclin permits newborn cerebral microvascular smooth muscle to dilate in response to specific stimuli. To test this hypothesis, four specific aims will be pursued using newborn pigs: l) Determine, in vivo, the ability of prostacyclin to restore cerebral vasodilator responses inhibited by indomethacin and by endothelial injury. 2) Examine the relationship between the ability of prostacyclin to restore vasodilation and changes in cyclic nucleotide metabolism. 3) Characterize, in vivo, the relationship between cerebral microvascular endothelial cell prostacyclin synthesis and smooth muscle cAMP in response to increased CO2. 4) Investigate the mechanisms by which prostacyclin modifies cerebral microvascular smooth muscle responses to hypercapnia. To accomplish these aims, techniques allowing investigation of intact cerebral microcirculation and primary culture of cells from newborn pig brain will be employed. Such research will be unique by studying the intact newborn cerebral circulation, isolated components that contribute to control of that circulation, and cocultures of these components to investigate mechanisms of communication. Cranial windows allow observation of cerebral microcirculation, collection of cortical periarachnoid fluid, selective endothelial damage, in vivo, and topical application of treatments and putative permissive agonists and inhibitors. Piglet cerebral microvascular endothelial and smooth muscle cells in primary culture will be used to study the effects of endothelial prostacyclin on smooth muscle cAMP responses to CO2. Effects of stable prostacyclin analogs on cerebral microvascular smooth muscle cAMP responses to CO2 will be evaluated. cAMP produced in response to CO2 by endothelial and vascular smooth muscle cells grown in isolation and together will be measured. To examine the relative contributions of intracellular and extracellular pH to the smooth muscle response to hypercapnia, using piglet cerebral microvascular smooth muscle cells in culture, we will measure cAMP production in response to decreases of pH-i with constant pH-e and in response to reduction of pH-e while maintaining pH-i. Selected potential cellular messenger pathways for involvement in the permissive role of prostacyclin in the microvascular smooth muscle response to hypercapnia will be evaluated. The effect of CO2 on iloprost receptor binding, the contributions of protein phosphorylation to the permissive role of prostacyclin and the kinases and substrates involved will be studied. Since disorders of cerebral circulation are major causes of morbidity and mortality in neonates and can result in lifelong disabilities in survivors better understanding of factors controlling newborn cerebral hemodynamics is badly needed.

提出的研究旨在解决以下统一假设： 内皮源性前列环素允许新生儿脑微血管 平滑肌响应特定刺激而扩张。为了测试这个 假设，使用新生猪将实现四个具体目标：l) 体内测定前列环素恢复大脑功能的能力 吲哚美辛和内皮损伤抑制血管舒张反应。 2）考察前列环素恢复能力之间的关系 血管舒张和环核苷酸代谢的变化。 3）表征， 在体内，脑微血管内皮细胞之间的关系 前列环素合成和平滑肌 cAMP 响应增加 二氧化碳。 4) 研究前列环素改变大脑功能的机制 微血管平滑肌对高碳酸血症的反应。为了完成这些 允许研究完整大脑的目标、技术 新生猪脑细胞的微循环和原代培养将 被雇用。通过研究完整的新生儿，此类研究将是独一无二的 脑循环，有助于控制的分离成分 这些成分的循环和共培养进行研究 沟通机制。颅窗可观察大脑 微循环，收集皮质蛛网膜周围液体，选择性 内皮损伤，体内和局部应用治疗和 假定的允许激动剂和抑制剂。仔猪脑微血管 原代培养的内皮细胞和平滑肌细胞将用于 研究内皮前列环素对平滑肌cAMP的影响 对二氧化碳的反应。稳定的前列环素类似物对大脑的影响 将评估微血管平滑肌 cAMP 对 CO2 的反应。营 内皮和血管平滑肌响应 CO2 产生 将测量单独生长的细胞和一起生长的细胞。要检查 细胞内和细胞外 pH 对平滑肌细胞的相对贡献 对高碳酸血症的肌肉反应，利用仔猪脑微血管平滑肌 在培养物中的肌肉细胞中，我们将测量 cAMP 的产生以响应 pH-i 随 pH-e 恒定而降低，并响应 pH-e 的降低 同时保持pH-i。选定的潜在细胞信使途径 参与前列环素在微血管中的许可作用 将评估平滑肌对高碳酸血症的反应。二氧化碳的影响 蛋白质磷酸化对伊洛前列素受体结合的贡献 前列环素以及激酶和底物的许可作用 所涉及的问题将被研究。由于脑循环障碍 新生儿发病和死亡的主要原因，并可导致 幸存者对终生残疾的因素有更好的了解 迫切需要控制新生儿脑血流动力学。