AJP - Heart and Circulatory Physiology, Vol 251, Issue 5 1000-H1008, Copyright © 1986 by American Physiological Society
Neurovascular function in the rat during pregnancy
J. L. Hart, W. Freas and S. M. Muldoon
Activity of the vascular neuroeffector junction was examined in pregnant
(PG) and nonpregnant (NPG) rats to determine whether changes could account
for the reported alterations in sympathetic control of the maternal
circulation. Caudal and mesenteric arteries were removed from NPG and 19-21
day PG rats and prepared for isometric tension recording.
Frequency-response measurements were obtained, followed by norepinephrine
(NE) and tyramine concentration-response measurements. The caudal artery
developed more tension in response to NE, tyramine, and electrical
stimulation than did the mesenteric artery; however, there were no
differences between vessels from NPG and PG rats. NE content, [3H]NE
accumulation, and effects of plasma on [3H]NE accumulation of NPG and PG
caudal arteries were also compared and found to be similar. Therefore,
vascular neuroeffector functions of NE release, receptor sensitivity, and
NE accumulation are not modified in the rat during pregnancy. Changes in
sympathetic control of the maternal circulation are likely to be dependent
on alterations at sites other than the neuroeffector junction.
