LOCALIZATION OF d-TUBOCURARINE-H³ AT THE MOTOR ENDPLATE

¹ Departments of Anesthesia and Pathology (Neuropathology), Stanford University School of Medicine, Palo Alto, California

The preparation of d-tubocurarine-H³ has permitted studies of its localization at the motor endplate through techniques of autoradiography. Five microcuries of d-tubocurarine-H³, equivalent to a dose of 0.6 µg/g b.wt., were injected into the tail vein of Swiss mice. The animals were sacrificed at the end of 1 min by decapitation and the diaphragm was removed. The latter was fixed in formalin vapor and sections were mounted after freezing in albumin. Cut sections (30 µ) were stained by a modification of the Koelle method adapted to prevent loss of the water-soluble d-tubocurarine. Autoradiography was performed with NTB3 emulsion. Development followed 10 to 21 days of exposure at 4°C. Localization of d-tubocurarine-H³ at the endplate was confirmed by light microscopy. Occasional evidence of strands of radioactivity leading into synaptic areas which contain dense radioactivity is suggestive of added preterminal localization of the drug.