Neuromuscular transmission in neonatal mice injected with serum globulin of myasthenia gravis patients.
Neuromuscular transmission was studied in neonatal mice following injection with serum globulin of patients with myasthenia gravis (MG). Compared to controls, these mice showed significant reduction in successive muscle action potentials evoked by repetitive nerve stimulation, amplitude of miniature endplate potentials, and postjunctional sensitivity to acetylcholine. There was no change in evoked isometric tension, quantal content of endplate potentials, or input resistance of the endplate membrane. These results confirm earlier reports of neuromuscular block in animals following injection of globulin of myasthenic patients, and demonstrate that decrease in amplitude of evoked potentials and of miniature endplate potentials is due to reduction in sensitivity to acetylcholine rather than in input resistance of the postsynaptic membrane. These findings are compatible with a postsynaptic defect in MG caused by a humorally mediated autoimmune mechanism.
D000328:Adult; D000368:Aged; D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006801:Humans; D007116:Immunization, Passive; D008297:Male; D008875:Middle Aged; D009045:Motor Endplate / Q000187:drug effects; D009115:Muridae; D009157:Myasthenia Gravis / Q000276:immunology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D011950:Receptors, Cholinergic / Q000187:drug effects; D012712:Serum Globulins / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*
D011950:Receptors, Cholinergic; D012712:Serum Globulins