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

The concentrations of lactate and hydrogen ions in maternal and fetal blood indicate that their net movement is from fetus to mother. Since these ions can cross the placenta in either direction, maternal acidosis will be reflected in the fetus. Low absolute values for lactate in both umbilical vein and artery of vigorous infants at birth indicate that under optimal conditions the fetus derives only a small proportion of energy from anaerobic glycolysis. Infants born following prolonged or complicated labors during which oxygen supply to the fetus is likely to be impaired are more acidotic and have significantly higher lactate levels. The concentration of pyruvate at birth shows no consistent relationship to the clinical condition of the infant, and neither the ratio of lactate to pyruvate nor excess lactate appears to be a better index of prenatal oxygen deprivation than the concentration of lactate. The acid-based components of amniotic fluid do not correlate either with the lactate concentration in fetal blood nor with the clinical condition of the infant at birth. In the minutes following birth, there is a further fall in blood pH, presumably due to a delayed influx of hydrogen ion from tissues. Thus, the composition of cord blood does not fully reflect the degree of fetal asphyxia during labor and delivery.

The relationship between V, CIN, and CPAH before and during diuresis as a result of infusion of D5W is shown in Figs 3 and 4; the relationship between V, osmolal clearance (COSM), and free water clearance (CH2O) is represented in Figs 5 and 6. The various clearances have been plotted against urine volume and compared with the regression lines for 17 infants (including seven in this paper) during the first three hours of life and prior to receiving an infusion.4 Despite a considerable scatter of data, there is no significant difference in the various correlations before and after infusion. A small decrease in fractional water reabsorption was observed after infusion, but not during spontaneous diuresis. No change in fractional osmolal reabsorption was observed during either spontaneous or infusion diuresis (Tables 2 and 3). In Table 4 the mean changes in the various measurements of renal function measured with infusion are compared with those occurring during spontaneous diuresis in the same infants. Again, except for the percentage of water reabsorbed after the infusion, there were no differences in the responses with the spontaneous diuresis compared to those observed after the infusion. See Images in the PDF File See Images in the PDF File See Images in the PDF File See Images in the PDF File See Table in the PDF File DISCUSSION Newborn infants during the first four hours of life are capable of having a prompt diuresis in response to an infusion of isotonic glucose. This diuresis is accompanied by an increase in renal plasma flow (RPF) and glomerular filtration rate (GFR).