Imipramine-serotonin induced myopathy.

Imipramine and serotonin (5-HT) were used to produce a myopathy in rats. Imipramine was used to simulate a defect in transport of 5-HT observed in the platelets of Duchenne9s dystrophy patients. The most effective dosage schedule was imipramine, 10 mg per kilogram, for 7 days followed by 5-HT, 100 mg per kilogram, 6 hours after the final imipramine dose. A single series of injections produced focal groups of necrotic and regenerating muscle fibers. In some rats, multiple series of injections resulted in a chronic myopathy with a predilection for proximal muscles, particularly quadriceps. In addition to skeletal muscle lesions, focal areas of myocardial damage were seen. The affected rats had a marked elevation of plasma creatine phosphokinase (including MB isoenzyme), serum glutamic oxaloacetic transaminase, and lactic dehydrogenase. Femoral nerve section did not affect the development of muscle lesions.