Migratory and proliferative characteristics of explanted rat aortic smooth muscle cells were studied in response to hypertension induced by 4 weeks of deoxycorticosterone-salt administration. Under low serum conditions (0.1% fetal bovine serum), over 80% of aortic medial explants from hypertensive rats yielded smooth muscle cell colonies after 8 days of culture while fewer than 10% of the control explants were positive. Time lapse video analysis of subsequent growth in the presence of 10% serum revealed that interdivision times of smooth muscle cells from hypertensive animals were significantly shorter than those in controls (p less than 0.01). Significant differences in proliferative capacity of smooth muscle cells were evident, even after one subculture (p less than 0.01). Comparison of these results with data from mechanical injury suggests that 4 weeks of deoxycorticosterone-salt hypertension can potentiate subsequent smooth muscle cell migration and growth in vitro to an extent similar to that observed with the combined effects of total endothelial denudation and wall distention by a balloon catheter.