ULTRASTRUCTURAL-LOCALIZATION OF CALCIUM IN NEUROMUSCULAR-JUNCTIONS OFSMOOTH AND SKELETAL-MUSCLES AFTER AMINOGLYCOSIDE ANTIBIOTICS TREATMENT

Aminoglycoside antibiotics are all capable of producing clinically sig nificant neuromuscular paralysis. Since part of the mechanism of actio n of these antibiotics at neuromuscular junction is a calcium-dependen t inhibition of acetylcholine release, so this experiment was carried out in vitro on both somatic (isolated rat phrenic-nerve hemidiaphragm ) and autonomic neuro-effector transmission (guinea-pig ileum) using g entamicin and amikacin, to determine the calcium contents at this leve l. Electron microscopic observations on gentamycin-and/or amikacin-tre ated materials, using potassium pyroantimonate method suggest a reduct ion of internal calcium in nerve terminals of both preparations.