Abstract
A prompt increase in glucagon (GLN) attributed to the fall in glucose (G) after birth has been observed in rat and human newborns immediately after delivery. This GLN surge also occurs in the newborn lamb, but is not preceded by a fall in G. To further explore this phenomenon, we investigated the term lamb during 1) delivery (D) and immediate umbilical cord cutting (CCT); 2) D with CCT delayed for 60 min. and 3) infusion of cyclic somatostatin (SRIF) to the fetus in utero and for 60 min. post D, while CCT was performed immediately after delivery. All animals were delivered by Caesarean section under local anesthesia. The characteristic surge in GLN was identified in 1, but did not occur in 2 while the cord was intact. However, after CCT in 2, plasma GLN rose from 59 ± 15 pg/ml (mean ± SEM) immediately prior to CCT, to 304 ± 99 pg/ml 15 min. later (p < 0.05). G did not change, confirming that hypoglycemia was not the stimulus for GLN secretion. Intravenous SRIF (50 μg bolus followed by 200 μg per hr) begun in the fetus 10 min. before delivery did not affect low fetal GLN. Despite ongoing SRIF, CCT was followed 15 min. later by a surge in GLN (δ 130 pg/ml; p < 0.01) and at 30 min. by a rise in G of 38 mg/dl (p < 0.05).
Conclusions: a) CCT evokes the neonatal GLN surge, b) the GLN rise is not related to curtailment of G supply, and c) unlike other stimuli for GLN, umbilical CCT overrides the suppressive effects of SRIF by undefined mechanisms.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sack, J., Grajwer, L., Sperling, M. et al. 55: Umbilical cord cutting: the stimulus to the glucagon surge in newborn lambs. Pediatr Res 10, 880 (1976). https://doi.org/10.1203/00006450-197610000-00052
Issue Date:
DOI: https://doi.org/10.1203/00006450-197610000-00052