Relative insensitivity to glucagon of sterol synthesis in cultured rat aortic smooth muscle cells

The smooth muscle cell plays an important role in the process of atherogenesis. In these experiments the effect of glucagon and dibutyryl cyclic AMP on sterol synthesis in cultured rat arterial smooth muscle cells was studied. Glucagon in concentrations of 1×10−9 mol/l inhibited the incorporation of sodium (2−14C)acetate into non-saponifiable lipids and digitonin precipitable sterols but lower concentrations of glucagon had no effect. In cells which were exposed to serum, dibutyryl cyclic AMP also resulted in a decrease in the incorporation of labelled acetate into sterols but when the cells were grown in serum free medium, dibutyryl cyclic AMP had no inhibitory effect on sterol synthesis. These results provide further evidence that sterol metabolism in arterial smooth cells may be influenced by hormones but suggest that glucagon is relatively less important than insulin in this respect.