Abstract 11148: Aging Impairs Endothelium-dependent Dilation Via Thiol-Oxidation in Coronary Arterioles in Smp 30 Deficiency Mice
Aging with oxidant stress is a major risk factor of coronary artery disease, however the underlying mechanisms have not been fully defined. Senescence marker protein 30 (SMP30) has been identified as an aging marker molecule, which decreases with aging and SMP 30 knock-out mice show a short life. To examine the effect of aging on coronary arterioles vasomotor tone, we measured endothelium-dependent (acetylcholine, ACh) and -independent vasodilation (sodium nitroprusside, SNP) of isolated, pressurized coronary arterioles (28±4 µm, diameter) from SMP30 KO and wild type (WT) mice. In SMP30 KO mice, ACh-induced vasoconstriction was appeared, which changed vasodilation with dithiothreitol, thiol-reducing agent (DTT, 0.1 µM), but L-NAME (0.3 mM) or sepiapterin (1 µM), tetrahydrobiopterin mimic, did not change vascular responses to ACh. In WT mice, ACh-induced vasodilation was appeared which was blunted with L-NAME. Inhibition of glutathione reductase by 1, 3-bis (2-chloroethyl)-1-nitrosourea (80 µM) in coronary arterioles of WT mice decreased ACh-induced vasodilation (n=10, p<0.01), which was restored by DTT. SNP-induced vasodilation was comparable. To evaluate the thiol oxidation, we measured the fluorescence of monochlorobimane (MCB, 0.2 µM) or monobromotrimetylammoniobimane (MBB, 20 µM) in coronary arterioles, which covalently labels the reduced total or extracellular-reduced thiols, respectively. Fluorescence level to MCB or MBB decreased in SMP30 KO mice (MCB 6.2±1.4, MBB 8.4±1.8 intensity/100 µm2, n=10 each), which level was restored with DTT treatment comparable to that of WT mice (MCB 64±7.8, MBB 76±8.8 intensity/100 µm2, p<0.01). Thus, S-glutathionylation with thiol-oxidation in endothelial cells is associated with endothelial dysfunction in SMP30 deficiency model. These results suggest that S-glutathionylation in eNOS reductase domain by oxidant stress is increased in aging, resulting in impaired endothelium-dependent vasodilation.
- © 2011 by American Heart Association, Inc.