REGIONAL ADRENAL BLOOD-FLOW RESPONSES TO ADRENOCORTICOTROPIC HORMONE IN FETAL SHEEP

被引:30
作者
CARTER, AM
RICHARDSON, BS
HOMAN, J
TOWSTOLESS, M
CHALLIS, JRG
机构
[1] UNIV WESTERN ONTARIO,LAWSON RES INST,DEPT OBSTET & GYNAECOL,LONDON N6A 4V2,ON,CANADA
[2] UNIV WESTERN ONTARIO,LAWSON RES INST,DEPT PHYSIOL,LONDON N6A 4V2,ON,CANADA
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1993年 / 264卷 / 02期
关键词
FETAL CIRCULATION; MICROSPHERES;
D O I
10.1152/ajpendo.1993.264.2.E264
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
To determine whether adrenocorticotropic hormone (ACTH) at plasma concentrations measured during mild hypoxemia and at term affects adrenal blood flow, we measured regional blood flows in five unanesthetized normoxemic fetuses (125-130 days gestation) during a 24-h intravenous infusion of ACTH-(1-24) in isotonic saline solution. Another rive fetuses received an infusion of vehicle. Blood flows were determined before the infusion, at 2 and 24 h from its onset, and 24 h afterward using radionuclide-labeled microspheres. Blood flow to the adrenal medulla was fivefold greater than that to the adrenal cortex. Adrenal blood flow rose 99% at 24 h of the ACTH infusion. There was a large increase in adrenal cortical blood flow of 272% at this time but medullary blood flow did not change significantly during ACTH infusion. The rise in cortical blood flow was attributable to decreased vascular resistance. No significant alterations occurred in fetal arterial blood pressure and heart rate, or in blood flow to other lower body organs of the fetus or to the placental cotyledons. These findings are consistent with the hypothesis that the increase in adrenal blood flow observed during fetal hypoxia is associated with changes in plasma ACTH concentration. They are also indicative of selective regulation of cortical and medullary blood flows in the sheep fetus at this stage of gestation.
引用
收藏
页码:E264 / E269
页数:6
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