Effect of diazepam on muscle weakness in a model of myasthenia gravis in rats

Rats chronically received alpha-bungarotoxin which caused a reduction of nicotinic acetylcholine receptors and weakness, especially of lip muscles. It was found that diazepam (0.75-2 mg kg-1, s.c.), after a 15 min period of excitation and increased lip weakness, caused sedation and some improvement of the lip. Even after 5 mg kg-1 diazepam, muscle function was not markedly affected and breathing appeared normal. It is concluded that sedation in rats by diazepam does not entail aggravation of the muscle weakness caused by a partial neuromuscular block.