Heterophagic function and rate of intralysosomal proteolysis during lysosomotropic agents administration

Abstract

Lysosomotropic agents--Triton WR 1339 and suramin--are taken up selectively into lysosomes during in vivo administration and cause specific changes of the particles. Overloading of rat liver lysosomes by Triton WR 1339 was accompanied by the labilization of lysosomes and an increased uptake of [14C]-bovine serum albumin ([14C]-BSA) by the rat liver. The rate of intralysosomal proteolysis was not altered. The capture of 125I-labelled poly(vinylpyrrolidone) (PVP) by the liver was slightly decreased. In the case of suramin administration (250 mg/kg b.w.) the uptake of labelled protein by the liver was not changed. The increased amount of acid-insoluble radioactivity in rat liver was caused by the decrease of intralysosomal protein digestion rate. The lysosomes overloaded by the two kinds of lysosomotropic agents--Triton WR 1339 (with no changes of intralysosomal proteolysis) and suramin (with decreased rate of proteolysis) did not prevent the uptake by liver of substances captured by the adsorptive ([14C]-BSA) or fluid ([125I]-PVP) endocytosis.