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：已对各种海豹物种进行了研究 适应窒息的实验模型。 海象 （Mirounga angustirostris）因其能力而被选择进行研究 以承受长时间的缺氧。 脾脏起着 在海豹潜水反应中发挥着重要作用，并被认为具有功能 作为含氧红细胞的储存库。 血细胞比容升高 潜水期间的水平使研究人员推测 脾脏在潜水过程中逐渐收缩，提供 具有含氧红细胞的动物。 这些研究的目标是 确定脾收缩、血细胞比容、 和潜水反应期间的肝窦体积。 方法：5 4 一个月大的象海豹是从加利福尼亚州 Ano Nuevo 收集的 在 UCSC 长海洋实验室举行。 这些动物被释放于 实验的结论。 这些动物被运送到 斯坦福大学每天进行 MR 研究。 每个印章都被放置 穿着约束夹克和定制的有机玻璃头盔 放置在密封件上并充满水以引发潜水 回复。 单次快速自旋回波脉冲序列产生 脾脏解剖的最佳描述。 基线、潜水和潜水后 以一分钟的间隔收集扫描。 每只动物潜水 4 次 次（潜水时间 5 至 8 分钟），总共完成 20 次 潜水数据集。 结果：MRI 数据分析揭示了 面部浸入后立即发生剧烈的脾收缩 动物的。 这种收缩使脾脏的体积减少到 大约是记录的静息音量的十分之一。 同时 还观察到触觉窦增大。 这个回应是 在所有 20 次潜水期间均观察到。 结论：与最初相反 对脾收缩模式的推测，似乎 脾脏立即将其内容物转移到肝窦 潜水的开始。 我们推测，通过骑兵的行动 括约肌，这些含氧红细胞缓慢计量进入 通过腔静脉循环，产生观察到的逐渐上升 血细胞比容。 从更大的背景来看，这些初步研究提出 对自然进化产生重要新见解的可能性 防止反复缺氧、缺血和 再灌注。