The effect of heparin on the relative myosin content of cultured smooth muscle cells of the pig aorta

Heparin inhibits the proliferation of aortic smooth muscle cells cultured in serum containing culture medium and leads to an increase of their relative myosin content. Using plasma as medium supplement the effect of heparin is not observed. Thrombin is able to inhibit the increase of myosin content caused by heparin. Platelet mitogens are not the point of attack of heparin. The possible mechanism of action of heparin on smooth muscle cells will be discussed.