Contraction and depolarization induced by fetal bovine serum in airway smooth muscle

Fetal bovine serum (FBS) contains S. hydroxy tryptamine (5HT) and an unknown factor that evokes a prolonged increase in muscle tone of the airway smooth muscle cells. 5HT is synthesized in the platelets during the process of serum production. The unknown factor includes phosphatidic acid (PA) and lyso-PA but the resulting amplitude of prolonged contraction is less compared to that caused by 5HT.