Studies on the permeability of rat liver lysosomes to carbohydrates

Abstract

1. The latency of nitrocatechol sulphatase activity was measured in rat liver lysosomes before and after preincubation in 0.25m solutions of 25 different carbohydrates. 2. Preincubation in disaccharides, hexitols, gluconate, glucuronate or lactate gave little or no rise in ;free' sulphatase activity, indicating that these compounds do not easily penetrate the lysosomal membrane, but incubation in monosaccharides or the lower glycitols caused a progressive loss of latency. 3. Rates of increase in ;free' activity were taken as an indication of rates of solute penetration into lysosomes and were correlated with the structure and molecular weight of each sugar. 4. Additional evidence for non-penetration of maltose was obtained by demonstrating that the latency of lysosomal alpha-glucosidase is independent of substrate concentration employed. 5. The results are discussed in the light of published data on the latency of lysosomal enzymes.

Characteristics of Sorbitol Uptake in Rat Glial Primary Cultures

“…In conclusion it is hypothesized that sorbitol uptake in glial primary cultures is mediated by a simple diffusion mechanism through a pore-like protein structure embedded in the lipid bilayer. Chromaffin granules from bovine adrenal glands are permeable to a variety of hexitols, whereas rat liver lysosomes apparently do not take up these compounds (Lloyd, 1969;Perlman, 1976). Therefore uptake of sorbitol may also be a particular property of the cells constituting the astrogliarich primary culture and is not in contrast to the postulated lack of permeability of sorbitol in cells of the peripheral nervous system (Cohen, 1987).…”

Transport Barriers in Transscleral Drug Delivery for Retinal Diseases

“…Other lysosomal enzymes, including ␣ -fucosidase, ␣ -mannosidase and ␤ -N-acetylglucosaminidase, have also been reported in bovine RPE [119] . Natural macromolecular drugs as well as xenobiotics may be degraded by lysosomal enzymes during transport across the RPE, as they are able to cross lysosomal membranes by passive diffusion [120,121] .…”

Progesterone-induced lysis of rat kidney lysosomes as studied by changes in light-absorbance

“…Relative permeabilities of the membrane to different solutes have been measured (Lloyd, 1969(Lloyd, , 1971Lee, 1970Lee, , 1971, by suspending the lysosomes in iso-osmotic solutions of different solutes and measuring the release of soluble enzymes, as an index of lysis.…”