Kirsch J R, Helfaer M A, Blizzard K, Toung T J, Traystman R J
Department of Anesthesiology/Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Am J Physiol. 1990 Nov;259(5 Pt 2):H1551-8. doi: 10.1152/ajpheart.1990.259.5.H1551.
We tested the hypothesis that 1- to 2-wk-old pigs (piglet) have improved recovery of cerebral blood flow (CBF), cerebral oxygen consumption (CMRO2), and somatosensory-evoked potentials (SEP) compared with 6- to 8-mo-old pigs (pig) after transient global cerebral ischemia. All animals were anesthetized with pentobarbital sodium. After tracheostomy ventilation was adjusted to maintain normoxia (arterial oxygen pressure, 100-150 mmHg) and normocarbia (arterial carbon dioxide pressure, 35-40 mmHg). Arterial blood gases, blood pressure, and hemoglobin concentration remained within physiological limits throughout the experiment. Cerebral ischemia was produced by sequentially tightening ligatures around the inferior vena cava and ascending aorta. During ischemia the electroencephalogram and SEP became isoelectric within 40 and 120 s, respectively. At 10 min of reperfusion hyperemia occurred in most brain regions (e.g., whole brain: piglet, 270 +/- 45%; pig, 316 +/- 48%). In pigs delayed hypoperfusion occurred in all regions except white matter. In contrast, piglets only had delayed hyperperfusion to the brain stem and caudate nucleus. Throughout reperfusion CMRO2 was decreased in pigs (3.3 +/- 0.4 to 1.9 +/- 0.2 ml.min-1.100 g-1) but was not different from control (2.7 +/- 0.3 ml.min-1.100 g-1) in piglets. By the end of reperfusion SEP amplitude was closer to control in piglets than pigs (55 +/- 9 vs. 32 +/- 4% of control). We conclude that 1- to 2-wk-old piglets have quicker return of CBF, CMRO2, and SEP to control values after global ischemia, which mechanistically may explain previous reports of improved neurological recovery in young animals after transient ischemia.
与6至8月龄的猪相比，1至2周龄的仔猪（小猪）在短暂性全脑缺血后，脑血流量（CBF）、脑氧耗量（CMRO2）和体感诱发电位（SEP）的恢复情况更好。所有动物均用戊巴比妥钠麻醉。气管切开术后，调整通气以维持正常氧合（动脉氧分压，100 - 150 mmHg）和正常碳酸血症（动脉二氧化碳分压，35 - 40 mmHg）。在整个实验过程中，动脉血气、血压和血红蛋白浓度均保持在生理范围内。通过依次收紧下腔静脉和升主动脉周围的结扎线来制造脑缺血。在缺血期间，脑电图和SEP分别在40秒和120秒内变为等电位。再灌注10分钟时，大多数脑区出现充血（例如，全脑：小猪，270±45%；猪，316±48%）。在猪中，除白质外所有区域均出现延迟性低灌注。相比之下，小猪仅脑干和尾状核出现延迟性充血。在整个再灌注过程中，猪的CMRO2降低（从3.3±0.4降至1.9±0.2 ml·min-1·100 g-1），但小猪与对照组（2.7±0.3 ml·min-1·100 g-1）无差异。再灌注结束时，小猪的SEP波幅比猪更接近对照组（分别为对照组的55±9%和32±4%）。我们得出结论，1至2周龄的仔猪在全脑缺血后，CBF、CMRO2和SEP更快恢复至对照值，从机制上可能解释了先前关于幼小动物短暂性缺血后神经功能恢复改善的报道。
