Fibrillation and accelerated AChR degradation in long-term muscle organ culture.

Evaluation of the precise molecular dynamics of endplate maintenance and reorganization has been limited by the lack of available in vitro preparations. We describe an organ culture preparation of mouse diaphragm muscle which permits long-term maintenance of muscle viability. Spontaneous fibrillations, increased levels of extrajunctional acetylcholine receptors, accelerated rates of junctional acetylcholine receptor turnover and maintenance of fine structure of denervated mouse diaphragm muscle in organ culture was evaluated under different culture conditions. Of several standard tissue culture media tested with and without fetal calf serum, medium 199 plus fetal calf serum was best for maintaining this muscle for greater than 2 weeks. The serum component could be partially eliminated by addition of non-glucose energy substrates such as D-beta-hydroxybutyric acid and L-glutamine. This preparation will permit a more controlled examination of the molecular components of endplate diseases.