AJP - Heart and Circulatory Physiology, Vol 246, Issue 6 811-H817, Copyright © 1984 by American Physiological Society
Delayed reversal of Goldblatt hypertension by angiotensin II infusion in the rat
A. Kumar, R. F. Bing, J. D. Swales and H. Thurston
Reversal of early Goldblatt two-kidney, one-clip hypertension is associated
with a fall in plasma renin. To define the role of this in blood pressure
normalization we maintained preoperative hypertension for 12 h after
unclipping or removal of the ischemic kidney, by angiotensin II or
norepinephrine infusions during continuous blood pressure monitoring. High
infusion rates of angiotensin II (1 microgram X kg-1 X min-1) were needed
to reproduce hypertensive pressures. On stopping angiotensin II there was a
rapid initial fall in blood pressure but not to normal (176 +/- 3.1 to 138
+/- 4.3 mmHg at 1 h), and a later slower fall to normal by 24 h (114 +/-
3.9). This response was identical to that of dextrose-infused animals (180
+/- 8.2 to 146 +/- 7.0 at 1 h and 113 +/- 5.6 at 24 h), apart from a
transient rise in blood pressure associated with hyperreninemia in
unclipped animals 12 h postinfusion. In contrast, after norepinephrine
blood pressure fell immediately to normal. Similar responses were seen in
normal rats after 12-h pressor infusions of angiotensin II or
norepinephrine. These results show that the fast and slow components of the
blood pressure fall following reversal of Goldblatt hypertension are
delayed but otherwise unaltered specifically by angiotensin II. The need
for pharmacologic doses, however, suggests that mechanisms in addition to
the direct vasopressor action of angiotensin II are involved.
