Responses of immunoreactive acth and bioactive acth to large
hemorrhage and resuscitation in conscious dogs.
Lilly, Michael P., Gary J. Gala, Barbara E. Sutherland, and Donald S.
Gann.
Departments of Surgery and Physiology, University of Maryland at
Baltimore, School of Medicine,, Baltimore, Maryland
APStracts 2:0057E, 1995.
We studied the effect of fluid resuscitation on immunoreactive ACTH
(irACTH) and bioactive ACTH (bioACTH) after hemorrhage in conscious
dogs. Animals (n=7) were bled 30% ( 25 ml/kg) over 3 min and 30 min
later were either resuscitated (43.3 ml/kg 0.9% NaCl over 10 min -
1.8 [lambda] hemorrhage volume) or not. Blood was reinfused after 210
min. Animals had both treatments (> 4 days apart). IrACTH, bioACTH,
cortisol, angiotensin-II and aldosterone increased rapidly after
hemorrhage. Resuscitation increased blood volume and cardiac output
to resting values, but arterial hypotension persisted. BioACTH and
irACTH decreased 40-90 min after hemorrhage in both groups, but each
decreased more rapidly after resuscitation. The elimination half-life
of bioACTH was shorter than that of irACTH, but neither was effected
by resuscitation. BioACTH / irACTH followed the same pattern with or
without resuscitation. Angiotensin-II and aldosterone remained
increased without resuscitation, but decreased promptly after
resuscitation. In conclusion, (1) saline infusion at 1.8 [lambda]
hemorrhage volume provides effective cardiovascular resuscitation
with resolution of hormonal responses to hemorrhage, (2) although
ACTH responses resolved with or without resuscitation, resuscitation
produced more rapid resolution without changing the parameters of
ACTH elimination, (3) the dynamics of the resolution of the ACTH
response to hemorrhage are similar whether induced by stimulus
removal or feedback inhibition.
Received 12 September 1994; accepted in final form 22 February
1995.
APS Manuscript Number E372-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.