Smolich J J, Cox H S, Berger P J, Walker A M, Eisenhofer G, Esler M D
Institute of Reproduction and Development, Monash University, Clayton, Victoria, Australia.
Circ Res. 1997 Sep;81(3):438-47. doi: 10.1161/01.res.81.3.438.
Little is known about the changes in the left ventricular (LV) kinetics of the catecholamines norepinephrine and epinephrine occurring at birth and their relationship to perinatal alterations in LV function and whole-body catecholamine kinetics. To address this issue, whole-body and LV catecholamine kinetics (radiotracer dilution methodology) and fetal LV output and myocardial blood flow (radioactive microspheres) were measured in chronically instrumented near-term fetuses and in the same animals 1 and 4 hours after birth. Between fetal and 1-hour lambs, LV external work increased 115% (P<.005); carotid arterial plasma norepinephrine concentration, 148% (P<.01); carotid arterial plasma epinephrine concentration, 546% (P<.005); LV norepinephrine spillover, a measure of LV sympathetic activity, 4.1-fold (P<.005); LV epinephrine spillover, 3-fold (P<.05); total-body spillover of norepinephrine, 52% (P<.025); and total-body spillover of epinephrine, 460% (P<.005). Arterial catecholamine concentrations and total-body catecholamine spillovers were unchanged between 1- and 4-hour lambs, but LV external work fell (P<.05) to a level still 77% greater than in fetal lambs (P<.005); LV norepinephrine spillover returned to near-fetal levels, and LV epinephrine spillover became undetectable. These results suggest that (1) a transient increase in LV sympathetic activity occurs at birth and may contribute to the immediate postnatal augmentation of LV performance, (2) organ differences in the pattern of sympathetic activation occur at birth, and (3) birth-related increases in LV sympathetic activity are accompanied by release of epinephrine from the heart.
关于出生时去甲肾上腺素和肾上腺素这两种儿茶酚胺的左心室（LV）动力学变化及其与围产期左心室功能改变和全身儿茶酚胺动力学的关系，目前所知甚少。为解决这一问题，我们采用放射性示踪剂稀释法测量了长期植入仪器的近足月胎儿及其出生后1小时和4小时同一动物的全身和左心室儿茶酚胺动力学，并用放射性微球测量了胎儿左心室输出量和心肌血流量。在胎儿期和出生后1小时的羔羊之间，左心室外部功增加了115%（P<0.005）；颈动脉血浆去甲肾上腺素浓度增加了148%（P<0.01）；颈动脉血浆肾上腺素浓度增加了546%（P<0.005）；左心室去甲肾上腺素溢出量（左心室交感神经活动的一种测量指标）增加了4.1倍（P<0.005）；左心室肾上腺素溢出量增加了3倍（P<0.05）；去甲肾上腺素全身溢出量增加了52%（P<0.025）；肾上腺素全身溢出量增加了460%（P<0.005）。在出生后1小时和4小时的羔羊之间，动脉儿茶酚胺浓度和全身儿茶酚胺溢出量没有变化，但左心室外部功下降（P<0.05）至仍比胎儿期羔羊高77%的水平（P<0.005）；左心室去甲肾上腺素溢出量恢复到接近胎儿期水平，左心室肾上腺素溢出量变得无法检测到。这些结果表明：（1）出生时左心室交感神经活动短暂增加，可能有助于出生后立即增强左心室功能；（2）出生时交感神经激活模式存在器官差异；（3）与出生相关的左心室交感神经活动增加伴随着心脏肾上腺素的释放。
