AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 1 50-R57, Copyright © 1995 by American Physiological Society
Hepatic denervation reduces adrenal catecholamine secretion during insulin-induced hypoglycemia
L. Lamarche, N. Yamaguchi and F. Peronnet
Groupe de Recherche sur le Systeme Nerveux Autonome, Faculte de Pharmacie, Universite de Montreal, Quebec, Canada.
The present study was designed to investigate the functional implication of
hepatic afferent nerves in controlling adrenal medullary counterregulatory
response to insulin-induced hypoglycemia in anesthetized dogs subjected to
an acute surgical denervation of the liver. Aortic glucose concentration
decreased similarly in the groups of dogs with hepatic denervation (n = 8)
and sham denervation (n = 8) reaching a glucose nadir 30 min after insulin
injection (0.15 IU/kg i.v.) from a control value of 89.46 +/- 3.15 and
88.91 +/- 2.86 mg/dl to 52.92 +/- 3.27 and 48.80 +/- 4.18 mg/dl (P <
0.05), respectively. The catecholamine output from the adrenal glands in
the sham group significantly increased (P < 0.05), reaching a maximum
level 45 min after insulin injection from a control value for epinephrine
of 86.35 +/- 26.65 ng/min and for norepinephrine of 32.14 +/- 11.68 ng/min
to 659.03 +/- 269.39 and 181.21 +/- 63.03 ng/min, respectively. By
contrast, however, adrenal catecholamine output increased only slightly in
the hepatic-denervated group during insulin-induced hypoglycemia, from
148.37 +/- 95.29 and 52.06 +/- 28.05 ng/min to 210.49 +/- 96.09 and 79.61
+/- 26.11 ng/min for epinephrine and norepinephrine, respectively, the
difference being statistically nonsignificant compared with the
corresponding preinjection control value. The maximum net response of
adrenal epinephrine and norepinephrine output observed in dogs with hepatic
denervation was significantly attenuated by approximately 90 and 82% of the
values obtained from the sham group, respectively. In a separate series of
experiments, aortic immunoreactive insulin and glucagon concentrations were
measured and found to be similar between hepatic-denervated and
sham-denervated groups after insulin-induced hypoglycemia.(ABSTRACT
TRUNCATED AT 250 WORDS)
