Treatment of porcine aortic smooth muscle cells with phorbol esters prevents nodulation in vitro

Vascular smooth muscle cells exhibit a unique pattern of growth in culture. They have the capacity for multilayer growth and form large macroscopic nodules. We find that nodulation is inhibited in the presence of phorbol esters and that there is a concomitant decrease in the production of a 38 kd secreted protein associated with nodulation in porcine smooth muscle. Examination of the organization of actin filaments within the cells using a rhodamine phalloidin stain indicates that there is a rearrangement of actin filaments in response to phorbol esters. This rearrangement increases the number of attachment sites to the culture surface and may contribute to the inhibition of nodulation in smooth muscle cells by phorbol esters.