Extracellular arginine rapidly dilates in vivo intestinal arteries and arterioles through a nitric oxide mechanism.
OBJECTIVE
Arginine used for nitric oxide formation can be from intracellular stores or transported into cells. The study evaluated the rapidity, and primary site of NO and vascular resistance responses to arginine at near physiological concentrations (100-400 microM).


METHODS
Arginine was applied to a single arteriole through a micropipette to determine the fastest possible responses. For vascular blood flow and [NO] responses, arginine was added to the bathing media.


RESULTS
Dilation of single arterioles to arginine began in 10-15 seconds and application over the entire vasculature increased [NO] in approximately 60-90 seconds, and flow increased within 120-300 seconds. Resting periarteriolar [NO] for arterioles was 493.6 +/- 30.5 nM and increased to 696.1 +/- 68.2 and 820.1 +/- 110.5 nM at 200 and 400 microM L-arginine. The blood flow increased 50% at 400-1200 microM L-arginine. The reduced arterial resistance during topical arginine was significantly greater than microvascular resistance at 100 and 200 microM arginine. All responses were blocked by L-NAME.


CONCLUSIONS
This study demonstrated arterial resistance responses are as or more responsive to arginine induced NO formation as arterioles at near physiological concentrations of arginine. The vascular NO and resistance responses occurred rapidly at L-arginine concentrations at and below 400 microM, which predict arginine transport processes were involved.
Pezzuto
Laura
L
Department of Cellular and Integrative Physiology, Indiana University Medical School, Indianapolis, IN 46202, USA.
Bohlen
H Glenn
HG
D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D001160:Arterioles / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007422:Intestines / Q000098:blood supply*; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
D009569:Nitric Oxide; D001120:Arginine