MR IMAGING OF AN ELEPHANT SEAL: MEASUREMENT OF SPLENIC DIVING RESPONSE

海象的 MR 成像：脾潜水反应的测量

• 批准号: 6309999
• 负责人: SHEILA THORNTON
• 金额: $ 1.55万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6309999
• 关键词: Mammalia; bioengineering /biomedical engineering; bioimaging /biomedical imaging; biomedical resource; cardiovascular system; magnetic resonance imaging

Introduction: Various seal species have been studied as experimental models for adaptation to asphyxia. Elephant seals (Mirounga angustirostris) were selected for study based on its ability to withstand extended periods of hypoxia. The spleen plays an significant role in the seal dive response and is believed to function as a reservoir for oxygenated erythrocytes. Elevated hematocrit levels during diving has led researchers to hypothesize that the spleen contracts gradually over the course of a dive, supplying the animal with oxygenated red blood cells. The goal of these studies was to determine the relationship between splenic contraction, hematocrit, and hepatic sinus volume during a diving response. Methods: Five 4 month old elephant seals were collected from Ano Nuevo, California and held at Long Marine Laboratory, UCSC. The animals were released at the conclusion of the experiment. The animals were transported to Stanford Univeristy on each day of an MR study. Each seal was placed in a restraining jacket, and a custom-made plexiglass helmet was placed on the seal and filled with water to ellicite a diving response. A single-shot fast spin echo pulse sequence yielded the best depiction of splenic anatomy. Baseline, diving, and post-dive scans were collected at one minute intervals. Each animal was dived 4 times (dive duration 5 to 8 min), resulting in a total of 20 complete diving data sets. Results: Analysis of the MRI data reveals a dramatic splenic contraction occurs immediately upon facial immersion of the animal. This contraction reduces the volume of the spleen to approximately one tenth of the recorded resting volume. Simultaneous enlargement of the haptic sinus is also observed. This response was observed during all 20 dives. Conclusions: Contrary to initial speculation on the pattern of splenic contraction, it appears that the spleen immediately transfers its contents to the hepatic sinus at the onset of a dive. We speculate that, through the action of the caval sphincter, these oxygenated erythrocytes are slowly metered into circulation via the vena cava, producing the observed gradual rise in hematocrit. Viewed in a larger context, these initial studies raises the possibility of important new insights into naturally evolved mechanisms of defense against recurring hypoxia, ischemia and reperfusion.

简介：已经研究了各种密封物种 适应窒息的实验模型。 大象密封 （Mirounga angustirostris）根据其能力选择进行研究 承受延长的缺氧时期。 脾脏扮演 在密封潜水响应中的重要作用，被认为起作用 作为氧化红细胞的水库。 血细胞比容升高 潜水期间的水平使研究人员假设 脾脏在潜水过程中逐渐收缩，提供 具有氧化红细胞的动物。 这些研究的目的是 确定脾收缩，血细胞比容之间的关系 和在潜水反应中的肝窦体积。 方法：五4 从加利福尼亚的Ano Nuevo收集了一个月的大象密封件 在UCSC的Long Marine实验室举行。 这些动物被释放 实验的结论。 这些动物被运送到 Stanford Univeristy在MR研究的每一天。 每个密封 穿着限制外套，定制的有机玻璃头盔是 放在海豹上，充满水到Ellicite A潜水 回复。 单发快速自旋回声脉冲序列产生 最佳描述脾解剖学。 基线，潜水和潜水后 一分钟间隔收集扫描。 每只动物都潜水4 时间（潜水持续时间5到8分钟），总共20个完整 潜水数据集。 结果：MRI数据的分析显示 剧烈的脾收缩立即发生在面部浸入后 动物。 这种收缩将脾脏的体积减少到 约占记录的静止体积的十分之一。 同时 还观察到触觉窦的扩大。 这个反应是 在所有20次潜水中都观察到。 结论：与初始相反 关于脾收缩模式的猜测，看来 脾脏立即将其内容物转移到肝窦 潜水的发作。 我们推测，通过骑兵的行动 括约肌，这些含氧的红细胞被缓慢地计入 通过腔静脉的循环，产生观察到的逐渐上升 血细胞比容。 在更大的情况下，这些初步研究提高了 对自然发展的重要新见解的可能性 防御反复出现低氧，缺血和的防御机制 再灌注。