Simonetta G, Rourke A K, Owens J A, Robinson J S, McMillen I C
Department of Physiology, University of Adelaide, Australia.
Pediatr Res. 1997 Dec;42(6):805-11. doi: 10.1203/00006450-199712000-00015.
We have investigated the impact of chronic restriction of placental function on circulating catecholamine concentrations and responses to the indirectly acting, sympathomimetic amine, tyramine, in the fetal sheep in late gestation. In 10 ewes, endometrial caruncles or placental placentation sites were removed before conception (placental restriction (PR) group). Fetal sheep in the PR group were hypoxemic throughout late gestation and growth-restricted (3.02 +/- 0.35 kg) when compared with control fetal sheep (4.30 +/- 0.29 kg; n = 8) at 140 d of gestation. Fetal plasma concentrations of noradrenaline and adrenaline were higher (p < 0.05) in the PR (7.06 +/- 3.17 pmol/mL and 2.89 +/- 2.01 pmol/mL, respectively) than in the control group (3.55 +/- 0.54 pmol/mL and 1.30 +/- 0.48 pmol/mL, respectively) throughout late gestation. Plasma noradrenaline, but not adrenaline concentrations, increased significantly between 110 and 140 d of gestation in both the PR and control group, and there was a significant inverse relationship between plasma noradrenaline and arterial PO2 in the PR and control groups (plasma noradrenaline = 12.34 - 0.40 PO2). In the PR group, plasma noradrenaline increased (p < 0.05) after tyramine infusion from 4.51 +/- 1.28 pmol/mL to a peak of 19.40 +/- 3.56 pmol/mL. In the control group, noradrenaline increased from 2.08 +/- 0.30 pmol/mL to a peak of 12.23 +/- 1.67 pmol/mL after tyramine infusion. There was no difference, however, in the maximal proportional changes in plasma noradrenaline concentrations in the PR (319 +/- 55%) and control (449 +/- 100%) groups after tyramine. We conclude that the most likely source of the increased plasma catecholamines in the PR group is enhanced catecholamine synthesis and secretion from developing sympathetic neurons.
我们研究了胎盘功能长期受限对妊娠晚期胎羊循环中儿茶酚胺浓度以及对间接作用的拟交感胺酪胺反应的影响。在10只母羊中,受孕前切除子宫内膜肉阜或胎盘着床部位(胎盘受限(PR)组)。与妊娠140天时的对照胎羊(4.30±0.29千克;n = 8)相比,PR组的胎羊在整个妊娠晚期均处于低氧血症状态且生长受限(3.02±0.35千克)。在整个妊娠晚期,PR组胎羊血浆去甲肾上腺素和肾上腺素浓度(分别为7.06±3.17皮摩尔/毫升和2.89±2.01皮摩尔/毫升)高于对照组(分别为3.55±0.54皮摩尔/毫升和1.30±0.48皮摩尔/毫升)(p < 0.05)。在PR组和对照组中,妊娠110至140天时血浆去甲肾上腺素浓度显著升高,但肾上腺素浓度未升高,并且PR组和对照组血浆去甲肾上腺素与动脉血氧分压之间存在显著负相关(血浆去甲肾上腺素 = 12.34 - 0.40×血氧分压)。在PR组中,输注酪胺后血浆去甲肾上腺素从4.51±1.28皮摩尔/毫升增加至峰值19.40±3.56皮摩尔/毫升(p < 0.05)。在对照组中,输注酪胺后去甲肾上腺素从2.08±0.30皮摩尔/毫升增加至峰值12.23±1.67皮摩尔/毫升。然而,酪胺作用后PR组(319±55%)和对照组(449±100%)血浆去甲肾上腺素浓度的最大比例变化并无差异。我们得出结论,PR组血浆儿茶酚胺增加的最可能来源是发育中的交感神经元增强了儿茶酚胺的合成和分泌。