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Evidence For The Existence Of A Constitutive Nitric Oxide Synthase In Vascular Smooth Muscle
Author(s) -
Cheah LS,
Gwee MCE,
Das R,
Ballard H,
Yang YF,
Daniel EE,
Kwan CY
Publication year - 2002
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2002.03707.x
Subject(s) - caveolae , nitric oxide synthase , vascular smooth muscle , nitric oxide , chemistry , contractility , endocrinology , medicine , biochemistry , biology , cell , smooth muscle
SUMMARY 1. We have identified a neuronal nitric oxide synthase (NOS)‐like constitutive form of NOS in vascular smooth muscle (VSM) using a functional contractility approach as well as immunohistochemical methods. 2. N G ‐Nitro‐ L ‐arginine methyl ester, N G ‐monomethyl‐ L ‐ arginine and N G ‐nitro‐ L ‐arginine ( L ‐NOARG), the competitive inhibitors of NOS, inhibited Mg 2+ ‐induced relaxation of de‐endothelialized rat aorta precontracted with phenylephrine (PE). This Mg 2+ relaxation of VSM was not affected by inhibitors of inducible NOS. 3. Electrical field stimulation (EFS; 30–70 Hz) caused relaxation of rat aorta in the presence of tetrodotoxin (therefore not a neurogenic effect) and this EFS relaxation was effectively inhibited by L‐NOARG, oxyhemoglobin and methylene blue. 4. Immunohistochemical studies of dog saphenous vein using antibodies raised against neuronal NOS indicated prominent staining along the plasmalemma in a punctate pattern similar to the distribution of antibodies against caveolin‐1, a major constituent of the plasmalemmal caveolae. 5. We propose that a constitutive NOS of non‐endothelial, non‐neuronal origin is present in a special caveolae domain of VSM cell membranes and could be activated by an ionic mechanism yet to be characterized.