Evidence of an adenosine-dependent mechanism in the hypotensive effect of L-arginine in man.
1. The hypothesis that endogenous adenosine could play a role in the haemodynamic response to L-arginine is investigated. 2. The study has been divided into two parts. The first part was a single blind, randomized, placebo-controlled study in which L-arginine i.v. infusion (0.07 mmol/kg per min) in five healthy volunteers caused a significant fall in systolic (-14.2%, from 129.0 +/- 8.2 to 110.6 +/- 8.5 mmHg; F = 62.89, P < 0.01), diastolic (-16%, from 80.0 +/- 7.9 to 67.2 +/- 7.0 mmHg; F = 18.97, P < 0.01) and mean (-15.5%, from 96.4 +/- 6.7 to 81.4 +/- 6.5 mmHg; F = 28.78, P < 0.01) arterial blood pressure, with a concomitant increase of plasma adenosine concentration (from 244.0 +/- 32.2 to 637.0 +/- 43.4 nmol/L; F = 79.3 P < 0.01). Maximal effects were obtained at the end of L-arginine infusion: haemodynamic parameters returned to basal values in about 30 min while adenosine concentrations normalized in about 15 min. Saline infusion had no effect on these parameters. 3. In the second study the effect of L-arginine i.v. infusion on arterial blood pressure, lower limb blood flow and plasma adenosine, before and after theophylline treatment (1000 mg/day for 3 days, p.o.) was examined.(ABSTRACT TRUNCATED AT 250 WORDS)
Laghi Pasini
F
F
Institute of Clinical Medicine, School of Medicine, University of Siena, Italy.
Frigerio
C
C
Blardi
P
P
Domini
L
L
De Giorgi
L
L
Borgogni
G
G
Pecchi
S
S
Cati
G
G
Franchi
M
M
Volpi
L
L
D000241:Adenosine / Q000097:blood*; D000328:Adult; D000704:Analysis of Variance; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D012039:Regional Blood Flow / Q000187:drug effects; D016037:Single-Blind Method; D013806:Theophylline / Q000008:administration & dosage / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
D001120:Arginine; D013806:Theophylline; D000241:Adenosine