AJP - Heart and Circulatory Physiology, Vol 251, Issue 3 612-H618, Copyright © 1986 by American Physiological Society
Responses of ACTH, epinephrine, norepinephrine, and cardiovascular system to hemorrhage
D. N. Darlington, J. Shinsako and M. F. Dallman
Hemorrhages of various magnitudes were performed on conscious rats, and
arterial pressure, heart rate, and plasma levels of adrenocorticotropin
hormone (ACTH), epinephrine, and norepinephrine were measured. Eight rats
were prepared with chronic femoral arterial cannulas and received a 10, 15,
or 20 ml/kg X 3 min hemorrhage in random order on day 4, 7, or 10 after
surgery. Mean arterial blood pressure, heart rate, and plasma ACTH,
epinephrine, and norepinephrine concentrations were determined before and
20 min after hemorrhage. Arterial blood pressure decreased significantly
immediately after each hemorrhage and slowly recovered over the next 20
min. Heart rate did not change during the 10 ml/kg X 3 min hemorrhage but
decreased significantly after 15 and 20 ml/kg X 3 min hemorrhages. Plasma
ACTH and epinephrine levels increased significantly 20 min after the 15 and
20 ml/kg X 3 min hemorrhages but not after 10 ml/kg X 3 min hemorrhage.
Norepinephrine increased significantly 20 min after the 20 ml/kg X 3 min
hemorrhage but not after the 10 or 15 ml/kg X 3 min hemorrhage. There was
no significant effect of time and repeated hemorrhages on resting levels of
plasma ACTH, epinephrine, norepinephrine, osmolality, or proteins. Since
hemorrhage leads to a fall in arterial pressure and a subsequent rise in
plasma ACTH, the relationship between plasma ACTH and mean arterial blood
pressure during hemorrhage was examined in both conscious and acutely
prepared pentobarbital sodium-anesthetized rats.(ABSTRACT TRUNCATED AT 250
WORDS)
