Efficacy of Cushing response during development in sheep.
Efficacy of Cushing response during development in sheep.
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绵羊发育过程中库欣反应的功效。
DOI：
10.1152/ajpheart.1991.261.2.h575
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
JonesJr,MD
中科院分区：
文献类型：
--
作者：
Backofen,JE;Koehler,RC;Harris,AP;Rogers,MC;Traystman,RJ;JonesJr,MD
当颅内压（ICP）接近平均主动脉压（MAP）时，平均主动脉压（MAP）升高（库欣反应）。我们将ICP升高至相当于正常基线MAP的水平，将模拟脑脊液（CSF）注入侧脑室，并对比了近足月胎羊、1周龄羔羊和戊巴比妥钠麻醉的成年羊的反应。CSF输注1周龄羔羊和成年羔羊在40分钟内MAP分别持续增加16 +/- 1和22 +/- 2 mmHg。然而，脑血流量分别下降了66%和57%，脑氧摄取量分别下降了34%和37%。在近足月胎儿中，在ICP升高3分钟时，MAP升高11 +/- 1 mmHg，脑血下降49%。然而，到15分钟时，MAP进一步增加（+17 +/- 2 mmHg），脑血流量几乎恢复。相反，出生后的羊，大脑O2摄取保持在整个胎儿。各组MAP升高的机制不同。在成人总外周阻力下降显着，而在胎儿和羔羊保持不变。各组心输出量增加，但由于外周阻力下降，心输出量增加对成人MAP升高相对更重要。此外，在胎儿的肠道和皮肤中发生了显著的血管收缩。库欣反应在近足月胎羊中发育良好。出生后，它可能会失去提供大脑基础代谢需求的有效性。
Mean aortic pressure (MAP) increases (Cushing response) when intracranial pressure (ICP) approaches MAP. We elevated ICP to levels equivalent to normal baseline MAP with infusion of mock cerebrospinal fluid (CSF) into the lateral cerebral ventricles and contrasted responses in near-term fetal sheep, 1-wk-old lambs, and adult sheep anesthetized with pentobarbital sodium. With CSF infusion 1-wk-old lambs and adults produced sustained increases in MAP of 16 +/- 1 and 22 +/- 2 mmHg, respectively, over a 40-min period. However, cerebral blood flow fell 66 and 57%, and cerebral O2 uptake fell 34 and 37%, respectively. In the near-term fetus, MAP increased by 11 +/- 1 mmHg and cerebral blood fell 49% at 3 min of elevated ICP. However, by 15 min MAP had increased further (+17 +/- 2 mmHg) and cerebral blood flow was nearly restored. In contrast to postnatal sheep, cerebral O2 uptake was maintained throughout in the fetus. The mechanism of increased MAP differed among groups. In adults total peripheral resistance fell significantly, whereas in the fetus and lamb it remained constant. Cardiac output increased in each group, but, because of the fall in peripheral resistance, increased cardiac output was relatively more important to the rise in MAP in adults. In addition, marked vasoconstriction occurred in intestines and skin in the fetus. The Cushing response is well-developed in near-term fetal sheep. After birth it may lose its effectiveness in providing for the basal metabolic demand of the brain.