Dexamethasone-induced hypertension in the rat: effects of L-arginine.
1. The effects of L-arginine treatment on dexamethasone-induced hypertension were examined in the Sprague-Dawley rat. Seventy rats were randomly divided into the following eight groups: sham, dexamethasone (5 and 10 micrograms/day, L-arginine (100 and 500 mg/kg per day), L-arginine (100 or 500 mg/kg per day) + dexamethasone (10 micrograms/day), L-arginine (520-797 mg/kg per day in food) + dexamethasone (5 micrograms/day). Systolic blood pressure (SBP), bodyweight and plasma nitrate/nitrite concentration were measured. 2. Dexamethasone (5 and 10 micrograms/day) increased SBP in both sham and L-arginine-treated rats. Dexamethasone at 10 micrograms/day decreased bodyweight, but did not alter plasma nitrate/nitrite concentrations. 3. L-Arginine (500 mg/kg per day, i.p.) increased plasma nitrate/nitrite concentrations in 10 micrograms/day dexamethasone-treated rats. L-Arginine did not alter blood pressure in either sham or dexamethasone-treated rats. 4. Dexamethasone-induced hypertension differs from adrenocorticotropic hormone (ACTH)-induced hypertension in the rat in that it is not modified by L-arginine. Thus, ACTH-induced hypertension cannot be explained simply in terms of glucocorticoid activity.
Li
M
M
Department of Medicine, St George Hospital, University of New South Wales, Sydney, Australia.
Fraser
T
T
Wang
J
J
Whitworth
J A
JA
D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D003907:Dexamethasone; D005938:Glucocorticoids; D006973:Hypertension / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
D005938:Glucocorticoids; D009566:Nitrates; D009573:Nitrites; D003907:Dexamethasone; D001120:Arginine