On the localisation of d-tubocurarine in rat liver lysosomes in vivo by electron microscopy and subcellular fractionation.

After i.v. injection in the rat, d-tubocurarine is taken up and concentrated by the liver. A method is developed for the visualisation of d-tubocurarine inside the liver cell by electron microscopy. Glutaraldehyde fixed liver blocks were immersed in an ammonium molybdate solution; d-tubocurarine was precipitated at sites of high concentration by molybdate, to form an insoluble d-tubocurarine-molybdate complex. This precipitate was found predominantly at the surface of lysosome-like particles, but also inside these organelles. In subcellular fractionation experiments, d-tubocurarine was found with a high relative specific "activity" in the lysosomal fraction, lending support to a lysosomal localisation of d-tubocurarine.