Abstract 20918: Mechanisms of Vascular Dysfunction in Aging
Aging is associated with a progressive loss of endothelial nitric oxide (eNO), chronic endothelial dysfunction, and inflammation. Calpains are a family of calcium-dependent proteases that have been recently implicated in the inflammation of aging organs. Several substrates for calpains have been identified, including cytoskeletal proteins, membrane receptors, protein kinases and transcription factors. μ-Calpain is one of calpain isoforms expressed in the vascular endothelium. By using low and high passage cultured endothelial cells as a model for endothelial aging, we tested the hypothesis that aging activates endothelial calpains with subsequent endothelial dysfunction. We found evidence of reduced calpastatin mRNA and protein expression levels in aging endothelial cells, a phenomenon which was associated with increased calpain activity. Immunoblot analysis revealed a calpain-dependent loss of eNOS/hsp90 association, which was restored following pharmacological inhibition of calpain activity. In vivo studies in the aging F1-F344xBN rat confirmed a role for calpains in endothelial dysfunction and inflammation of the aging vascular system. Studies were performed in 4-6 months old (young), 19 months old (middle aged), and 32-35 month old (old) rats. Intravital microscopy studies coupled with western blot analysis of calpain expression levels demonstrated increased calpain activity in the vascular endothelium of the mesenteric microcirculation. In vivo measurements of eNO revealed that calpain depresses eNO bioavailability in vivo and increases expression of endothelial cell adhesion molecules. These actions of calpain in the microcirculation were also prevented by pharmacological inhibition of calpain.
Author Disclosures: R. Scalia: None. I. Rom: None.
- © 2016 by American Heart Association, Inc.