AJP - Endocrinology and Metabolism, Vol 256, Issue 5 E682-E685, Copyright © 1989 by American Physiological Society
Role of antiglucocorticoid RU 486 on dexamethasone-induced hypertension in rats
M. Kalimi
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
This study was conducted to investigate whether hypertension induced by
long-term in vivo administration of dexamethasone in rats could be
prevented by the newly synthesized potent antiglucocorticoid drug RU 486.
Subcutaneous implantation of 5 mg of dexamethasone pellets in
Sprague-Dawley rats resulted in a rapid increase in the blood pressure that
remained elevated during the 3 wk of experimental observation. RU 486 (50
mg) administered alone surprisingly showed slight elevation of blood
pressure over untreated control animals. However, the blood pressure
leveled off to control levels over the next 2 wk. Interestingly, a 50-mg RU
486 pellet implanted along with 5 mg of dexamethasone effectively prevented
the dexamethasone-induced increase in blood pressure. RU 486 administered
together with dexamethasone prevented dexamethasone-induced diuresis and
urinary Na+ excretion. However, RU 486 was unable to reverse the weight
loss or involution of thymus observed by long-term treatment with
dexamethasone alone. No abnormalities were found in either kidneys or
hearts in any of the treated groups under microscopic examination. These
results suggest that RU 486 successfully prevented the hypertension
produced by the long-term administration of dexamethasone in male
Sprague-Dawley rats.
