Rm. Cowett et al., THE CONTRIBUTION OF GLUCOSE TO NEONATAL GLUCOSE-HOMEOSTASIS IN THE LAMB, Metabolism, clinical and experimental, 47(10), 1998, pp. 1239-1244
A multiplicity of substrates and hormones interact to influence neonat
al glucose homeostasis. Based on prior studies in our laboratory, we h
ypothesized that glucose alone does not tightly control neonatal gluco
se homeostasis. Fifteen spontaneously delivered, mixed-breed term lamb
s, weighing 4.7 +/- 0.9 kg (mean +/- SD) were studied at 4.7 +/- 0.6 d
ays after birth following administration of 100 mu Ci D[6,6-H-3(2)] gl
ucose in 0.9% NaCl by the prime plus constant infusion technique to me
asure glucose production. After a baseline period, five lambs received
8.5 mg.kg(-1).min(-1) glucose in combination with the following to is
olate the contribution of glucose: somatostatin to block insulin, gluc
agon, and growth hormone release; metyrapone to block cortisol release
; phentolamine to block alpha-adrenergic release; and propranolol to b
lock beta-adrenergic release (glucose + blockade). Five lambs received
the above without the glucose infusion (blockade). Five lambs continu
ed to receive 0.9% NaCl alone as the diluent for the isotopic tracer t
hroughout the study (control). The glucose + blockade group had a sign
ificant increase in plasma glucose (P < .0001) and a significant incre
ase in total glucose appearance (P < .0001) compared with both the blo
ckade and control groups. Under conditions of glucose infusion at a ra
te 49% greater than the basal rate, the endogenous glucose production
rate persisted such that there was only an evanescent decrease compare
d with that of the control group, which was not statistically differen
t over time. As a substrate, glucose does not tightly control neonatal
glucose homeostasis.