Effects of different injurious stimuli on cell death, proliferation, and collagen secretion by rabbit aortic smooth muscle cells and human umbilical vein endothelial cells in culture.

Rabbit aortic smooth muscle cells were exposed to hypoxia and the DMSO-soluble particulate matter of cigarette smoke (DSP) and the effects on the cells were compared to those of ultraviolet (UV) light, a wellknown cytotoxic stimulus. Hypoxia reduced cell proliferation and collagen secretion as long as it lasted (1, 3 and 24 hours), but these effects were reversible and no persistent toxic effects were seen for the next 48 hours, measured as leakage of prelabelled [3H]-thymidine from cells. DSP caused similar changes to those produced by UV-light. Proliferation and collagen secretion were reduced, and these effects were not reversible when the stimulus was removed after one hour. DSP was toxic as there was an increased leakage of [3H]-thymidine from cells. Increasing the concentration of DSP caused more pronounced effects while extending the incubation time to 3 hours did not, the latter being in contrast to the consequences of UV-irradiation. Endothelial cells were more sensitive to the effects of DSP than smooth muscle cells. DSP diluted 1:25 compared to the smallest concentration that had significant effects on smooth muscle cells reduced proliferation of endothelial cells, and in dilutions of 1:4 almost all of the cells detached. A possible role for DSP in the development of atherosclerosis is discussed.