RESUMEN
The endplate (+EP) and non-endplate (-EP) distribution of molecular formas of acetylcholinesterase (AChE) was compared in the dimorphic levator ani and disphragm muscles from adult male rats. Enzyme activity was measured by the thicholine method and AchE forms were separated on the basis of solubility in sodium phosphate buffer of different ionic strenght. For the dimorphic levator ani muscle, total AchE activity was 342.6 ñ 18.9 nmol ASCh hydrolyzed min-1 muscle-1, 90% of which was globular and predominated in the-EP region (78%). The asymmetric forms were almost exclusively detected in the +EP region (9%). In diaphragm muscler, total AChE activity was 176.7 ñ 11.0 units; 66% was mainly globular and located in the-EP region (56%); the asymmetric forms (34%) were either in -EP (11%) or + EP (23%) regions. Thus, a greater proportion of globular form was presented in the dimorphic levator ani muscle than in diaphragm muscle. In view of the control exerted by testosterone on dimorphic muscles, its is suggested that the grater synthesis of the globular form in the levator ani occurs under the trophic influence of testosterone