Fig. 2.

Endogenous and exogenous nitric oxide (NO) regulate extracellular lysyl oxidase-like 2 (LOXL2) abundance and activity in vascular smooth muscle cells (VSMCs). Ai–Aiv: representative Western blot (Ai), densitometry analysis of LOXL2 protein in the cell-derived extracellular matrix (ECM; Aii), conditioned cell culture media (CCM; Aiii), and LOXL2 activity in the CCM (Aiv) in the human aortic smooth muscle cells (HASMCs) in the presence or absence of human aortic endothelial cell (HAEC) coculture and the endothelial nitric oxide synthase inhibitor nitro-l-arginine methyl ester (l-NAME; 100 μM; n = 6, *P < 0.05, **P < 0.01 by Kruskal Wallis test with Dunn’s post hoc test). IB, immunoblot. Bi and Bii: representative Western blots of LOXL2 protein in the aortic matrix of intact and endothelium-denuded young (3–4 mo old) and old (18+ mo old) wild-type (WT) mice (Bi; n = 5 in each group; *P < 0.05, **P < 0.01, and ***P < 0.001 by 2-way ANOVA); basal NO production was lower in the aorta of old WT mice when compared with young (Bii; n = 5 in each group, *P < 0.05, **P < 0.01 by Wilcoxon rank sum test). Ci–Civ: representative Western blot (Ci) of LOXL2 protein abundance and densitometry analysis in the ECM (Cii), CCM (Ciii), and LOX activity in the CCM (Civ) of HASMCs with increasing concentration of the nitric oxide donor S-nitrosoglutathione (GSNO; n = 6, *P < 0.05, **P < 0.01 by Kruskal Wallis test with Dunn’s post hoc test). RFU, relative fluorescence units.