AN EXPERIMENTAL DEVELOPMENT OF ESOPHAGEAL ACHALASIA ON DOGS BY THE ADMINISTRATION OF PHTHALIMIDOMETHYLO, O-DIMETHYLPHOSPHORODITHIOATE

Esophageal achalasia-like phenomena have been produced experimentally on 18 dogs after the administration of the anticholinesterase agent, phthalim-idomethyl O, O-dimethylphosphorodithioate (PMP). The agent was administered intramuscularly three times a week for 40 weeks. The dose to each group was varied from 0.5, 10, 20, 25, and as much as 50mg per kg of body weight. In the group with the dose of 20mg per kg of body weight, the symptom of vomiting or dysphagia appeared most markedly. Some dogs showed diarrhea, bloody stool and hoarseness. Upon x-ray examination, dogs showed the failure of passage at the esophago-cardiac junction and the dilatation of the lower esophagus. Intraluminal pressure recording showed the abnormal simultaneous rises of the swallowing pressure wave. Histological examination around the Auerbach's plexus showed pycnotic nuclei, swelling of ganglion cells, fibrosis and round cell infiltration. The MAO stain showed no changes. The acethylcholine-esterase stain suggested the suppression of the enzyme activity.