AJP - Heart and Circulatory Physiology, Vol 260, Issue 3 827-H831, Copyright © 1991 by American Physiological Society
Effect of adrenalectomy or sympathectomy on spinal cord blood flow in hypothermic rats
A. Iwai, W. W. Monafo and S. G. Eliasson
Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.
We used [14C]butanol distribution to measure regional spinal cord blood
flow (RSCBF) in three groups of pentobarbital-anesthetized rats: 1) normals
(n = 16); 2) after bilateral adrenalectomy (n = 18); and 3) after excision
of the abdominal sympathetic chains (n = 12). Half of the rats in each
group were maintained near normothermia; the remainder were colled to a
rectal temperature of 25-27 degrees C. In intact rats, there was a 24-37%
increase in RSCBF during hypothermia in the cord region C3-L6 inclusive.
Neither operative procedure altered RSCBF during normothermia. In
hypothermic adrenalectomized rats, RSCBF was elevated only in the C3-C5
cord segment. After sympathectomy, RSCBF was unchanged during hypothermia.
In the cauda equina, flow fell in all hypothermic rats. The
hypothermia-associated increases in RSCBF were not related to changes in
mean arterial blood pressure. We conclude that adrenalectomy near-totally
ablates the hypothermia-associated increase in RSCBF measured in intact
rats and that abdominal sympathectomy totally ablates it. This evidence
complements morphological evidence for adrenergic innervation of the spinal
cord vasculature.
