CLOSURE OF THE PRIMATE DUCTUS ARTEROISUS

灵长类动物动脉导管闭合

• 批准号: 7562473
• 负责人: RONALD I CLYMAN
• 金额: $ 6万
• 依托单位: TEXAS BIOMEDICAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7562473
• 关键词: Affect; Anatomy; Appearance; Area; Behavior; Bioluminescence; Birth; Blood flow; Cell Death; Cells; Closure; Computer Retrieval of Information on Scientific Projects Database; Condition; Constriction procedure; Contracts; Diffusion; Drops; Ductus Arteriosus; Enzymes; Fetus; Freezing; Funding; Glucose; Glycogen; Glycolysis; Grant; HIF1A gene; Hour; Hypoxia; Image; In Situ Nick-End Labeling; In Vitro; Incidence; Incubated; Institution; Legal patent; Link; Muscle; Newborn Infant; Numbers; Nutrient; Oxygen; Papio; Primates; Research; Research Personnel; Resistance; Resources; Sheep; Source; Staining method; Stains; Surrogate Markers; Tissues; United States National Institutes of Health; Vascular Endothelial Growth Factors; day; falls; fetal; in vivo; mRNA Expression; postnatal

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In contrast with the full term ductus, constriction of the immature ductus frequently fails to cause luminal obliteration and only moderately increases diffusion distances for oxygen and nutrients within its muscle media. This is associated with less cell death and less remodeling and leads to persistent ductus luminal blood flow after birth. In addition to the absence of anatomic remodeling, the immature newborn ductus progressively loses its ability to constrict during the first days after birth. The explanation for the impaired contractility of the persistently patent immature newborn ductus is currently unknown. During the past year we examined ductus from full term and immature fetal and newborn baboons to determine how constriction of the ductus arteriosus affects the concentrations of oxygen, glucose, glycogen, and ATP in the ductus wall in vivo; and, to determine how these changes relate to the appearance of cell death in the vessel's wall and to the ability of the ductus to constrict after birth. We determined cell death (using TUNEL staining), energy status (using enzyme-linked bioluminescence imaging) and tissue hypoxia (using HIF1 alpha and VEGF mRNA expression as a surrogate marker) in frozen ductus obtained from baboons: 185d fetus (n= 11), 1-2 d old full term newborn (n=10), 125 d fetus (n=14), 125 d (6 d PRN) newborn (with open ductus, n=16), 125 d (6 d PRN) newborn (with closed ductus, n=10). In the full term baboon ductus, the expression of our two surrogate markers of hypoxia (HIF1alpha and VEGF) increased and the average concentrations of ATP, glucose and glycogen decreased following postnatal ductus constriction. The concentrations of ATP, glucose, and glycogen were significantly related to the degree of ductus constriction. In the full term baboon ductus there was also a significant relationship between the degree of ductus constriction and the logarithmic transformation of the number of TUNEL-positive cells (our indicator of cell death) (area of ductus lumen versus TUNEL log10: r=-0.92, p15% TUNEL-positive cells) only occurred when the ductus was closed and there was no Doppler flow through its lumen. In the premature ductus, ATP concentrations were directly related to tissue glucose concentrations but not to glycogen concentrations. Similarly, cell death (TUNEL staining) was related to tissue glucose concentrations but not to glycogen concentrations in the immature ductus. This is consistent with our previous in vitro studies that showed that the primary substrate utilized during glycolysis is glucose, not glycogen. In addition, during tight constriction and tissue hypoxia, the immature ductus actually develops regions where glycogen concentrations were actually greater than those observed in the fetus. We have previously shown that ductus rings, incubated in vitro under hypoxic conditions, develop both regions of glycogen depletion as well as regions of glycogen surplus: interestingly, the regions of glycogen surplus are more commonly seen in the immature than the mature ductus. We hypothesize that this adaptive mechanism could add to the ability ,of the immature ductus to tolerate episodes of hypoxia and nutrient shortage making it more resistant to developing postnatal cell death and permanent closure. Although the changes in HIF1alphaNEGF expression and ATP concentrations were significantly related to the degree of ductus constriction in the premature ductus, we were surprised to find that both HIF1alphaNEGF expression and ATP concentrations were still significantly altered after birth even when the immature ductus remained open and continued to have persistent luminal blood flow. We used ductus arteriosus from preterm lamb fetuses to determine if the drop in ductus ATP concentrations, that occur after birth in preterm newborns with an open ductus, is sufficient to alter ductus contractility. We examined the contractile behavior of immature sheep ductus in vitro exposed to 80% 02 and two different concentrations of glucose. At low glucose concentrations, ATP concentrations were not maintained and fell to 31 % of the starting (0 hr) fetal ductus levels. This is similar to the in vivo drop in ATP concentration observed in the immature newborn baboon ductus that remains open after birth. In contrast, in the rings exposed to normal glucose concentrations, ATP concentrations were stable during the 24 hr incubation, There was no difference between the mo experimental groups in the incidence of cell death (TUNEL staining) or remodeling during the in vitro incubation (24 hours). Ductus with normal concentrations of glucose and ATP contracted when exposed to 80% oxygen for 24 hours; in contrast, ductus with low glucose and low ATP failed to contract when exposed to 80% oxygen.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 与足月乳管相比，未成熟乳管的收缩通常不会引起管腔闭塞，仅适度增加其肌肉介质内氧气和营养物质的扩散距离。这与较少的细胞死亡和较少的重塑有关，并导致出生后持续的导管腔血流。除了没有解剖重建外，未成熟的新生儿导管在出生后的最初几天内逐渐失去收缩能力。对于持续未成熟新生儿导管的收缩力受损的解释目前尚不清楚。 在过去的一年中，我们检查了来自足月和未成熟胎儿和新生狒狒的导管，以确定动脉导管的收缩如何影响体内导管壁中氧、葡萄糖、糖原和ATP的浓度;并确定这些变化如何与血管壁中细胞死亡的出现和出生后导管收缩的能力相关。我们确定细胞死亡（使用TUNEL染色），能量状态（使用酶联生物发光成像）和组织缺氧（使用HIF 1 α和VEGF mRNA表达作为替代标志物）：185天胎儿（n= 11）、1-2天足月新生儿（n=10）、125天胎儿（n=14）、125天（6天PRN）新生儿125 d（6 d PRN）新生儿（10 d闭乳）。 在足月狒狒导管中，我们的两个缺氧替代标志物（HIF 1 α和VEGF）的表达增加，出生后导管收缩后ATP、葡萄糖和糖原的平均浓度降低。三磷酸腺苷、葡萄糖和糖原的浓度与导管狭窄程度显著相关。在足月狒狒乳管中，乳管收缩程度与TUNEL阳性细胞数量的对数转换（我们的细胞死亡指标）之间也存在显着关系（乳管管腔面积与TUNEL log 10：r=-0.92，p15% TUNEL阳性细胞）仅在乳管关闭且无多普勒血流通过其管腔时发生。 在早产儿导管中，ATP浓度与组织葡萄糖浓度直接相关，但与糖原浓度无关。同样，细胞死亡（TUNEL染色）与组织葡萄糖浓度有关，但与未成熟导管中的糖原浓度无关。这与我们之前的体外研究一致，该研究表明糖酵解过程中使用的主要底物是葡萄糖，而不是糖原。此外，在紧密收缩和组织缺氧期间，未成熟的导管实际上发育出糖原浓度实际上大于在胎儿中观察到的糖原浓度的区域。我们以前已经表明，导管环，在体外培养缺氧条件下，发展的区域糖原耗尽以及区域糖原盈余：有趣的是，区域糖原盈余更常见于未成熟的比成熟的导管。我们假设这种适应机制可以增加未成熟导管耐受缺氧和营养缺乏的能力，使其更能抵抗出生后细胞死亡和永久关闭。 尽管HIF 1 α NEGF表达和ATP浓度的变化与早产儿导管收缩的程度显著相关，但我们惊奇地发现，即使未成熟的导管保持开放并继续有持续的管腔血流，HIF 1 α NEGF表达和ATP浓度在出生后仍显著改变。我们使用来自早产羔羊胎儿的动脉导管来确定导管开放的早产新生儿出生后导管ATP浓度的下降是否足以改变导管收缩力。我们检查了暴露于80%02和两种不同浓度的葡萄糖的未成熟绵羊导管的体外收缩行为。在低葡萄糖浓度下，ATP浓度不能维持，并下降至起始（0小时）胎儿导管水平的31%。这类似于在出生后保持开放的未成熟新生狒狒导管中观察到的ATP浓度的体内下降。相比之下，在暴露于正常葡萄糖浓度的环中，ATP浓度在24小时孵育期间是稳定的。在体外孵育（24小时）期间，在细胞死亡（TUNEL染色）或重塑的发生率方面，mo实验组之间没有差异。当暴露于80%氧气24小时时，具有正常浓度葡萄糖和ATP的导管收缩;相反，当暴露于80%氧气时，具有低葡萄糖和低ATP的导管不收缩。