Buckley N M, Jarenwattananon M, Gootman P M, Frasier I D
Am J Physiol. 1987 Jan;252(1 Pt 2):H118-24. doi: 10.1152/ajpheart.1987.252.1.H118.
The capability of the developing intestinal circulation to maintain a vasoconstrictor response during postganglionic adrenergic nerve stimulation or norepinephrine infusion was examined in 34 swine aged 6 h to 2 mo anesthetized with pentobarbital sodium. Aortic and portal venous pressures, electrocardiogram (ECG), and blood flow (F) through the superior mesenteric artery were recorded, and intestinal vascular resistance (MVR) was calculated as mean pressure difference per mean F. Baroreceptor reflex inhibition by bilateral occlusion of the carotid arteries increased MVR, section of the splanchnic nerve and postganglionic fibers decreased MVR, and short-latency F decreases were obtained during mesenteric nerve stimulation (MNS). Latencies for the decreases in F shortened with age and with increasing MNS frequency (5-17 Hz) at any age. Prolonging MNS for 60 s at 10 or 12 Hz led to sustained high MVR in 6-h to 7-day-old animals; however, MVR decreased toward control before the end of the 60-s MNS period in animals 1 to 2 mo old. Intra-arterial infusion of norepinephrine (0.5 microgram X kg-1 X min-1) decreased F and increased MVR in all animals; but by 5 min of infusion, F was returning toward control level in all but the youngest. This demonstration that the least mature intestinal circulation was least capable of autoregulatory escape from vasoconstriction provides further evidence of its functional immaturity.
在34头用戊巴比妥钠麻醉的6小时至2月龄猪中，研究了发育中的肠循环在节后肾上腺素能神经刺激或去甲肾上腺素输注期间维持血管收缩反应的能力。记录主动脉和门静脉压力、心电图（ECG）以及通过肠系膜上动脉的血流（F），并将肠血管阻力（MVR）计算为平均压力差除以平均F。双侧阻断颈动脉对压力感受器反射的抑制作用增加了MVR，切断内脏神经和节后纤维降低了MVR，并且在肠系膜神经刺激（MNS）期间获得了短潜伏期的F降低。F降低的潜伏期随着年龄增长以及在任何年龄下随着MNS频率增加（5 - 17 Hz）而缩短。在10或12 Hz下将MNS延长60秒会导致6小时至7日龄动物持续出现高MVR；然而，在1至2月龄动物中，MVR在60秒MNS期结束前降至对照水平。动脉内输注去甲肾上腺素（0.5微克·千克⁻¹·分钟⁻¹）会使所有动物的F降低并使MVR增加；但输注5分钟后，除最年幼的动物外，所有动物的F都恢复到对照水平。这种最不成熟的肠循环最不能从血管收缩中自动调节逃脱的证明，进一步证明了其功能不成熟。
