The relationship between concentrations of vasopressin in plasma and cerebrospinal fluid (CSF) was examined under basal and hypoxic conditions in unanesthetized and unrestrained adult female sheep. Under basal conditions mean (± SE) concentration of vasopressin (4.1 ± 0.3 pg/ml) in CSF was significantly (p< 0.001) higher than the concentration in arterial plasma (2.4 + 0.2 pg/ml). There was a significant positive correlation between CSF and plasma vasopressin concentrations (r = 0.66, p < 0.01). The introduction of severe hypoxia by exposure of the sheep to an inspired gas mixture of 5% O₂ in N₂, a known stimulus to systemic release of vasopressin, was associated with an increase in the concentration of vasopressin in plasma to 339 ± 65 pg/ml and CSF to 19 ± 3.9 pg/ml. This increase of vasopressin in CSF was delayed in time with respect to the increases in the plasma and of a lesser magnitude. With moderate hypoxia (10% O₂ in N₂ exposure) no increase in CSF or plasma vasopressin concentration was observed, suggesting a threshold response. Intravenous infusion of vasopressin to achieve plasma values comparable to those seen with hypoxia was not accompanied by a significant increase in CSF vasopressin concentration. Thus, severe hypoxia is a potent stimulus for release of vasopressin into both CSF and plasma. Furthermore, data suggest that vasopressin may be released into CSF via a separate route from that released into plasma.

Terbutaline, a resorcinol derivative of isoprenaline, is primarily an adrenergic j3 2 -receptor agonist [25]. Terbutaline has been demonstrated äs being a potent inhibitor of myometrial contractlity in vitro [1]. Recent clinical trialshave confirmed the agent's tocolytic activity in both spontaneous and oxytocin-stimulated labor [2,3,15]. the investigations showed that terbutaline was well tolerated maternally despite a moderate tachycardia. Antepartum fetal heart rate monitoring and APGAR scores did not demonstrate any unusual or adverse effects on the fetus in human [2,3,15] or animal [6,7] studies. However, presently there are no systematic clinical or other investigations showing the effect of varying matemal doses on the fetus and on uteroplacental circulation. This study was undertaken to investigate doserelated effects of terbutaline on immature fetal lambs. The drug was infused into the maternal circulation in one phase and directly into the fetal circulation in another during oxytocin-induced labor. The fetal cardiovascular and acid-bäse Status was monitored continuously. Paris V, France 1977-1978. Assistant, füll time, Faculty of Medicine ofSfax, Tunisia 1978-1979 l Materials and methodsTen pregnant ewes and their fetuses (including two sets of twins) were prepared under spinal anesthesia äs described previously [7]. Catheters were introduced into the fetal carotid artery and jugular vein and into the amniotic cavity at hysterotomy. The femoral artery and vein and main maternal uterine vein were also catheterized. An electromagnetic flow probe (Micron Instruments, Calif.) was placed around the uterine artery supplying the pregnant hörn. A minimum period of three days was allowed