Plasma membrane-associated endothelial nitric oxide synthase and activity in aging rat aortic vascular endothelia markedly decline with age

• Published in: Archives of biochemistry and biophysics 2006-10, Vol.454 (1), p.100-105
• Main Authors: Smith, Anthony R., Visioli, Francesco, Hagen, Tory M.
• Format: Article
• Language: English
• Subjects: Aging; Aging - metabolism; Akt; Animals; Caveolin-1; Cell Membrane - enzymology; Cells, Cultured; Cytosol - enzymology; Endothelial nitric oxide synthase; Endothelium; Endothelium, Vascular - enzymology; Enzyme Activation; Golgi Apparatus - enzymology; Heat shock protein 90; In Vitro Techniques; Male; Nitric oxide; Nitric Oxide Synthase Type III - metabolism; Rats; Subcellular distribution; Tissue Distribution
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2006.02.017

The mechanisms leading to the age-related loss of endothelial nitric oxide (NO) and NO-dependent vasodilation remain largely unknown. Freshly isolated endothelium from young (6 months) and old (36 months) F344 × BrN rats were analyzed for endothelial nitric oxide synthase (eNOS) protein, its subcellular distribution, and association with regulatory proteins. Results show that both vessel ring vasoreactivity and A23187-induced eNOS activity in isolated endothelial cells significantly ( p ⩽ 0.05) declined with age. Levels of cGMP, a reliable marker for NO bioactivity also declined significantly ( p ⩽ 0.01). However, no change in overall eNOS protein was evident. Subcellular fractionation studies revealed an age-related loss in active, plasma membrane-bound eNOS relative to eNOS in the Golgi/cytosol of the endothelium. Plasma membrane-associated eNOS in aged endothelium was also less complexed with the activating proteins Hsp90 and Akt and more associated with to caveolin-1, which inhibits eNOS activity. These results suggest that age-dependent loss of NO may be partly caused by differences in eNOS subcellular distribution and its association with inhibitory proteins.