Scroop G C, Marker J D, Martin A A
J Dev Physiol. 1986 Aug;8(4):283-95.
Intravenous injections of PGI2 (1.5-12 X 10(-5) nmol/ml blood volume) caused hypotensive responses which increased with dose in both fetal and neonatal sheep. In the fetus, as gestation advanced and basal heart rate declined, the predominant heart rate response to PGI2 changed progressively from bradycardia to tachycardia. In the neonate, PGI2 always induced tachycardia and the effect was unrelated to postnatal age. The bradycardia induced by PGI2 in young fetal sheep (123-132 days) was converted to tachycardia following either bilateral vagotomy or cervical cord transection. Heart rate was unchanged by PGI2 in fetal sheep subjected to both procedures. The depressor response to PGI2 was enhanced by cervical cord transection but was essentially unchanged in fetal sheep subjected to either bilateral vagotomy alone or combined vagotomy and cord section. Despite increased plasma renin activity following PGI2, the cardiovascular response was not modified by bilateral nephrectomy. It is concluded that while intravenous PGI2 has a similar depressor effect in both fetal and neonatal sheep the heart rate response is age-dependent. Bradycardia is the principal response in young fetal sheep and is mediated by vagal pathways while tachycardia, which is the more usual response in older sheep, is probably sympathetic in nature.
静脉注射前列环素（PGI2，剂量为1.5 - 12×10⁻⁵纳摩尔/毫升血容量）可引起胎儿和新生绵羊的降压反应，且该反应随剂量增加而增强。在胎儿中，随着孕期进展和基础心率下降，PGI2引起的主要心率反应逐渐从心动过缓转变为心动过速。在新生绵羊中，PGI2总是诱发心动过速，且该效应与出生后年龄无关。在年轻胎儿绵羊（123 - 132天）中，PGI2诱发的心动过缓在双侧迷走神经切断术或颈髓横断术后转变为心动过速。在接受这两种手术的胎儿绵羊中，PGI2对心率无影响。颈髓横断术增强了PGI2的降压反应，但在仅接受双侧迷走神经切断术或迷走神经切断术与脊髓横断术联合手术的胎儿绵羊中，PGI2的降压反应基本未变。尽管PGI2注射后血浆肾素活性增加，但双侧肾切除术后心血管反应未改变。结论是，虽然静脉注射PGI2在胎儿和新生绵羊中具有相似的降压作用，但心率反应具有年龄依赖性。心动过缓是年轻胎儿绵羊的主要反应，由迷走神经通路介导，而心动过速是年长绵羊更常见的反应，可能本质上是由交感神经介导的。
