Fig. 1.

Biological roles of endothelial NO: inhibition of platelets aggregation, modulation of leukocyte–endothelial interactions, modulation of smooth muscle cell proliferation, and maintenance of vascular tone. eNOS is activated by physiological and metabolic stimuli, shear stress, and receptor-dependent agonists. S1177 phosphorylation site is an important regulatory mechanism for eNOS activity. eNOS catalytic activity depends on the intracellular localization to caveolae and the protein–protein interactions with caveolins and hsp-90. NO activates cGMP, inducing PKG-dependent relaxation of smooth muscle cells and increasing luminal diameter and blood flow. P phosphorylation; S1177 serine 1177, Hsp-90 heat shock protein-90, PKG serine–threonine-specific protein kinase G