Abstract
Catecholamine (CAT) release has been observed in near term fetal sheep in response to a variety of stimuli including hypoxia, maternal hypovolemia or exercise and parturition. In earlier studies of fetal sympatho-adrenal activity in response to parturition it has not been possible to differentiate the effects of labor, intrapartum asphyxia, delivery and UCC on CAT release. We have used the acutely exteriorized near term fetal lamb to study the effects of delivery and UCC on CAT release. Results show that delivery alone evokes an elevation of newborn plasma CAT which is brief and followed by return to basal values by 30 min. Subsequent UCC evokes a marked release of norepinephrine (NE) and epinephrine (E) (peak plasma levels 32,000 pg/ml and 35,000 pg/ml), maximal at 5 min. and persisting over the 4 hour study period. There is a concomitant rise in plasma free fatty acids (FFA) and reversal of post-delivery hypothermia. The magnitude of the CAT surge is inversely proportional to the degree of acidosis; a blunted FFA response and slower correction of hypothermia were observed in more acidotic animals despite higher CAT levels. Conclusions: 1) UCC is an important stimulus for fetal CAT release. 2) UCC stimulated neurosympathetic activity is of sufficient magnitude to influence many metabolic and cardiovascular functions. 3) Acidosis stimulates CAT release in the near term ovine fetus. 4) Acidosis obtunds neonatal chemical thermogenesis.
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Padbury, J., Diakomanolis, E., Hobel, C. et al. 279 SYMPATHO-ADRENAL RESPONSE TO UMBILICAL CORD CUTTING (UCC). Pediatr Res 15 (Suppl 4), 486 (1981). https://doi.org/10.1203/00006450-198104001-00290
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DOI: https://doi.org/10.1203/00006450-198104001-00290