L-arginine transport in humans with cortisol-induced hypertension.
A deficient L-arginine-nitric oxide system is implicated in cortisol-induced hypertension. We investigate whether abnormalities in L-arginine uptake contribute to this deficiency. Eight healthy men were recruited. Hydrocortisone acetate (50 mg) was given orally every 6 hours for 24 hours after a 5-day fixed-salt diet (150 mmol/d). Crossover studies were performed 2 weeks apart. Thirty milliliters of blood was obtained for isolation of peripheral blood mononuclear cells after each treatment period. L-arginine uptake was assessed in mononuclear cells incubated with L-arginine (1 to 300 micromol/L), incorporating 100 nmol/L [3H]-l-arginine for a period of 5 minutes at 37 degrees C. Forearm [3H]-L-arginine extraction was calculated after infusion of [3H]-L-arginine into the brachial artery at a rate of 100 nCi/min for 80 minutes. Deep forearm venous samples were collected for determination of L-arginine extraction. Plasma cortisol concentrations were significantly raised during the active phase (323+/-43 to 1082+/-245 mmol/L, P<0.05). Systolic blood pressure was elevated by an average of 7 mm Hg. Neither L-arginine transport into mononuclear cells (placebo vs active, 26.3+/-3.6 vs 29.0+/-2.1 pmol/10 000 cells per 5 minutes, respectively, at an l-arginine concentration of 300 micromol/L) nor L-arginine extraction in the forearm (at 80 minutes, placebo vs active, 1 868 904+/-434 962 vs 2 013 910+/-770 619 disintegrations per minute) was affected by cortisol treatment; ie, that L-arginine uptake is not affected by short-term cortisol treatment. We conclude that cortisol-induced increases in blood pressure are not associated with abnormalities in the l-arginine transport system.
Chin-Dusting
Jaye P F
JP
Alfred and Baker Medical Unit, Wynn Domain, Baker Heart Research Institute and Alfred Hospital, Prahran, Australia. j.chin@alfred.org.au
Ahlers
Belinda A
BA
Kaye
David M
DM
Kelly
John J
JJ
Whitworth
Judith A
JA
D000328:Adult; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D001916:Brachial Artery / Q000378:metabolism; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology*; D006973:Hypertension / Q000139:chemically induced; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male
D001120:Arginine; D006854:Hydrocortisone