Elastin uptake in HASMCs is regulated by MMP and NO. HASMCs were cultured with elastin fragments (1 mg/ml) in the presence of vehicle control (DMSO), the broad-spectrum MMP inhibitor NNGH (50 μmol/L), or L-NAME (5 mmol/L) for 24 hours. Cultures were monitored by time-lapse video-microscopy, and the time point at which an elastin fragment appeared within a cell was recorded. Forty-five cells were scored for each treatment. A: Selected images taken at hourly intervals, showing accumulation of elastin fragments within a cell. Arrows denote elastin fragments. Scale bar = 10 μm. B: Time course of elastin uptake. Mean ± SEM (n = 4). C: Percentage of HASMC-containing elastin fragments at 6, 12, and 24 hours. Black bars represent control cells, gray bars represent NNGH-treated cells, and white bars represent L-NAME-treated cells. Median + range (n = 4); *P < 0.05, **P < 0.01, ***P < 0.001; two-way analysis of variance.