Impact of the L-arginine-Nitric Oxide Pathway and Oxidative Stress on the Pathogenesis of the Metabolic Syndrome

Table 2: Summary of the Features of the Three NOS Isoforms

	nNOS or type I	iNOS or type II	eNOS or type III
First identification	neurones	macrophages	Endothelium
Molecular weight (kDa)	160	130	133
Cromossomal localisation	12p24.2	17cen-q12	7q35-36
Major function	Neuronal messenger	Immunocytotoxicity	Relaxation of VSM^*
Levels of NO produced	pmoles	nmoles	pmoles
Regulation of expression	Constitutive Up-regulated by sex hormones, nerve and brain injury	Not normally present Expression induced by cytokines and endotoxin	Constitutive Up-regulated by sex hormones and shear stress

^* VSM=vascular smooth muscle.

Refs. [³,⁸-¹⁰,¹²]