Pleiotropic effect of serum on beating rat heart cell cultures and their modulation by hormones.

The multiple effects of serum on metabolic activities and macromolecular syntheses of heart cell cultures are discussed in this chapter. This pleiotropic response, which is linearly related to the amount of serum used, allowed us to quantitatively test the growth-promoting activity of different hormones. In addition, the possible mediation of the serum effects by cyclic nucleotides is considered.