AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 2 341-R348, Copyright © 1986 by American Physiological Society
Sympathetic control of adrenal secretion of enkephalins after hemorrhage in awake dogs
W. C. Engeland, D. F. Bereiter and D. S. Gann
Adrenomedullary secretion of methionine (Met)-enkephalin and of leucine
(Leu)-enkephalin was measured in awake trained dogs subjected to 10 or 20%
hemorrhage. Enkephalin secretory rates increased in proportion to the
magnitude of hemorrhage with the ratio of Met-enkephalin to Leu-enkephalin
being approximately 4:1. Arterial concentrations of enkephalins reflected
adrenal secretion only in dogs exhibiting the largest secretory responses
to hemorrhage. Cross-correlation analysis of 12 individual experiments
showed that Met-enkephalin and epinephrine secretory rates were maximally
correlated at 0-min delay, suggesting that enkephalins are cosecreted with
catecholamines. The molar ratio in adrenal venous blood of epinephrine to
Met-enkephalin ranges from 480 +/- 50 to 570 +/- 60. Chronic denervation of
the adrenal by removing thoracic and lumbar splanchnic nerves prevented the
Met-enkephalin and catecholamine secretory responses to hemorrhage. These
data show that the adrenal medulla secretes enkephalins in response to
stimuli activated by hemorrhage. These findings suggest that secretion of
opiate-like peptides into the peripheral circulation may be a component of
the sympathetic response to trauma.
