| Abstract: | Cultured pectoral muscle from 11-day-old chick embryos was treated for 48 h with phenytoin (diphenylhydantoin, DPH) in concentrations ranging from 15 to 270 microgram/ml on days 7-9 in vitro. Acetylcholinesterase (AChE, EC 3.1.1.7), creatine phosphokinase (CPK, EC 2.7.3.2), and lactic dehydrogenase (LDH, EC 1.1.1.27) activities, 3H]leucine incorporation into protein, and total protein of the cultures decreased in a dose-related manner with DPH concentrations of 30 microgram/ml and greater. Total AChE activity and AChE activity released into the medium were specifically decreased with 15 microgram DPH per millilitre. In cultures treated chronically with 15 microgram DPH per millilitre on days 5-13 in vitro, total AChE activity and AChE activity released into the medium were 66.0 +/- 13.2 and 64.7 +/- 11.8% of untreated controls, respectively, but cellular AChE activity, cell protein, and 3H]leucine incorporation into protein were unaffected. The results indicate that DPH specifically decreases the total net synthesis of AChE activity by a direct action on cultured chick embryo muscle. |
