Objective:To investigate the role of saturated free fatty acids (SFFAs) in the pathogenesis of atherosclerosis by determining the effects of FFAs on diacylglycerol (DAG) synthesis and protein kinase C (PKC) activity in cultured bovine aortic smooth muscle cells. Methods:Bovine aortic smooth muscle cells, cultured in vitro, were treated with 200 ?mol/L SFFAs (including palmitate and stearate) and unsaturated FFAs (including oleate and arachidonate) separately for 24 h. Then the cells were lysed and the lipids were treated with lysis buffer and separation buffer. DAG level and PKC activity were calculated through measuring the radioactivity of 32P-PA by liquid scintillation counting (1 cpm=6.17?108 Bq). Results:Incubation of the cells with saturated FFAs(palmitate or stearate, 200 ?mol/L, for 24 h) induced significant increase in DAG concentrations (927.2 and 1 533.3 pmol/106 cells by palmitate and stearate, respectively) compared with that of the control cells (190 pmol/106 cells,P