scholarly journals Studies on the permeability of rat liver lysosomes to carbohydrates

1969 ◽  
Vol 115 (4) ◽  
pp. 703-707 ◽  
Author(s):  
J B Lloyd
Keyword(s):  
Molecular Weight ◽  
Rat Liver ◽  
Substrate Concentration ◽  
Lysosomal Enzymes ◽  
Published Data ◽  
Progressive Loss ◽  
Liver Lysosomes ◽  
Before And After ◽  
Rat Liver Lysosomes ◽  
Free Activity

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 α-glucosidase is independent of substrate concentration employed. 5. The results are discussed in the light of published data on the latency of lysosomal enzymes.

scholarly journals A study of permeability of lysosomes to amino acids and small peptides

1971 ◽  
Vol 121 (2) ◽  
pp. 245-248 ◽  
Author(s):  
J. B. Lloyd
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Small Peptides ◽  
Liver Lysosomes ◽  
Before And After ◽  
Rat Liver Lysosomes ◽  
Free Activity ◽  
Good Agreement

The latency of nitrocatechol sulphatase activity was measured in rat liver lysosomes before and after preincubation in 0.25m solutions of five amino acids, three dipeptides and a tripeptide. Rates of increase in ‘free’ activity were taken as an indication of rates of solute penetration into lysosomes and were correlated with the structure of each molecule studied. In general permeability was greater in solutions of pH7 than of pH5 or 6, and dipeptides entered more rapidly than amino acids or triglycine. The conclusions are in good agreement with those obtained by other methods.

Pharmacologic perturbation of rat liver lysosomes: Effects on release of lysosomal enzymes and of lipids into bile

1988 ◽  
Vol 95 (4) ◽  
pp. 1088-1098 ◽  
Author(s):  
Richard B. Sewell ◽  
Susan A. Grinpukel ◽  
Alan R. Zinsmeister ◽  
Nicholas F. LaRusso
Keyword(s):  
Rat Liver ◽  
Lysosomal Enzymes ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes

scholarly journals Hydrolysis of membrane phospholipids by phospholipases of rat liver lysosomes

1979 ◽  
Vol 182 (2) ◽  
pp. 599-606 ◽  
Author(s):  
Donald E. Richards ◽  
Robin F. Irvine ◽  
Rex M. C. Dawson
Keyword(s):  
Phospholipase C ◽  
Rat Liver ◽  
Lysosomal Enzymes ◽  
Microsomal Fraction ◽  
Water Soluble ◽  
Membrane Phospholipids ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes ◽  
Hydrolysis Of

(1) The hydrolysis of 32P- or myo-[2-3H]inositol-labelled rat liver microsomal phospholipids by rat liver lysosomal enzymes has been studied. (2) The relative rates of hydrolysis of phospholipids at pH4.5 are: sphingomyelin>phosphatidylethanolamine>phosphatidylcholine> phosphatidylinositol. (3) The predominant products of phosphatidylcholine and phosphatidylethanolamine hydrolysis are their corresponding lyso-compounds, indicating a slow rate of total deacylation. (4) Ca2+ inhibits the hydrolysis of all phospholipids, though only appreciably at high (>5mm) concentration. The hydrolysis of sphingomyelin is considerably less sensitive to Ca2+ than that of glycerophospholipids. (5) Analysis of the water-soluble products of phosphatidylinositol hydrolysis (by using myo-[3H]inositol-labelled microsomal fraction as a substrate) produced evidence that more than 95% of the product is phosphoinositol, which was derived by direct cleavage from phosphatidylinositol, rather than by hydrolysis of glycerophosphoinositol. (6) This production of phosphoinositol, allied with negligible lysophosphatidylinositol formation and a detectable accumulation of diacylglycerol, indicates that lysosomes hydrolyse membrane phosphatidylinositol almost exclusively in a phospholipase C-like manner. (7) Comparisons are drawn between the hydrolysis by lysosomal enzymes of membrane substrates and that of pure phospholipid substrates, and also the possible role of phosphatidylinositol-specific lysosomal phospholipase C in cellular phosphatidylinositol catabolism is discussed.

Effect of benz(a)pyrene and constant light exposure on rat liver lysosomes and biliary excretion of lysosomal enzymes

2005 ◽  
Vol 139 (1) ◽  
pp. 34-37 ◽  
Author(s):  
A. B. Pupyshev ◽  
E. M. Gutina ◽  
R. G. Fedina ◽  
S. V. Michurina ◽  
A. V. Shurlygina ◽  
...  
Keyword(s):  
Rat Liver ◽  
Biliary Excretion ◽  
Lysosomal Enzymes ◽  
Light Exposure ◽  
Constant Light ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes

scholarly journals Mechanisms of loss of latency of lysosomal enzymes. Effects of incubation on the properties of lysosomal membranes

1980 ◽  
Vol 186 (1) ◽  
pp. 243-256 ◽  
Author(s):  
R C Ruth ◽  
W B Weglicki
Keyword(s):  
Rat Liver ◽  
Incubation Medium ◽  
Lysosomal Enzymes ◽  
Fragility Curves ◽  
Osmotic Fragility ◽  
Lysosomal Membrane ◽  
Assay Medium ◽  
Additional Amount ◽  
Before And After ◽  
Free Activity

1. The effects of sucrose and KCl on the loss of latency of lysosomal enzymes caused by incubation at 37 degrees C, pH 7.4, were examined by using Triton-filled lysosomes from rat liver and two fractions from livers of rats not injected with Triton. 2. After incubation, the percentage free activity of lysosomal enzymes was measured before and after cooling to 0 degrees C in order to determine the amount of latency lost at 37 degrees C without cooling and the additional amount lost on cooling the incubated lysosomes to 0 degrees C. 3. The latency that is lost without cooling is first decreased and then increased by increasing the osmotic strength of the incubation medium with KCl, or with sucrose in the presence of KCl. However, if the osmotic strength is increased with sucrose alone, loss of latency is decreased up to 0.25M-sucrose, but is increased only slightly at higher sucrose concentrations. Apparently the lysosome is permeated by hyperosmolar KCl but not by sucrose during incubation. 4. If the osmotic strength of the assay medium is increased with KCl, the loss of latency caused by incubation for 60 min in hyperosmolar KCl is repressed. Thus it appears that a KCl-permeated lysosome can be obtained which is relatively stable until exposure to lower osmolarities. 5. The loss of latency caused by cooling incubated lysosomes to 0 degrees C is largely eliminated if the osmotic strength of the medium in which the lysosomes are cooled is raised sufficiently with either sucrose or KCl. 6. Osmotic-fragility curves were obtained after incubation for 1 and 60 min at iso-osmoticity (0.2M-KCl or 0.25 M-sucrose). Although little loss of latency occurs at iso-osmoticity, lysosomes incubated for 60 min display greatly increased fragility on exposure to hypo-osmolar KCl, hypo-osmolar sucrose or hyperosmolar KCl. 7. It is suggested that permeability to KCl at 37 degrees C and the increase in fragility on exposure to hypo-osmolar conditions are both consequences of injury, probably from enzymic action, sustained by the lysosomal membrane during incubation at 37 degrees C.

Effects of ATP on lysosomes: protection against hyperosmolar KCl

1983 ◽  
Vol 245 (1) ◽  
pp. C68-C73 ◽  
Author(s):  
R. C. Ruth ◽  
W. B. Weglicki
Keyword(s):  
Protective Effect ◽  
Rat Liver ◽  
Liver Lysosomes ◽  
Subsequent Exposure ◽  
Atp Analogues ◽  
Rat Liver Lysosomes ◽  
Free Activity ◽  
Reversible Nature ◽  
Damaging Effects

After incubation at 37 degrees C in isosmolar (200 mM) KCl, rat liver lysosomes are susceptible to damage caused by brief exposure to hyperosmolar (greater than 200 mM) KCl. Lysosomes that are exposed to hyperosmolar KCl do not undergo significant lysis as long as they are maintained at hyperosmolar conditions; however, they will lyse on being returned to lower osmolarities. If the hyperosmolar KCl-treated lysosomes are intermittently transferred into equally hyperosmolar sucrose, they no longer undergo lysis on subsequent exposure to lower osmolarities; this confirms the reversible nature of the hyperosmolar KCl-induced damage. Thus the hypothesis that the hyperosmolar KCl damage involves an isosmotic permeating of the lysosome by KCl appears reasonable. The increase caused by the hyperosmolar KCl in free activity of beta-N-acetyl-D-glucosaminidase is reduced by about 50% by ATP but not by ATP analogues. ATP protects provided that it is added either before, or simultaneously with, exposure of the lysosomes to hyperosmolar KCl. However, if the ATP is not added until the lysosomes are already in the presence of the hyperosmolar KCl, it does not reverse the damaging effects of the KCl even though actual lysis has not yet occurred at the time of the ATP addition. The protective effect is established very rapidly, because ATP added simultaneously with the addition of the hyperosmolar KCl protects to the same extent as does ATP added any time prior to the KCl addition. The protective effect requires Mg2+ and is not supported by Ca2+. Maximal protection is provided by 5 X 10(-4) M ATP. It is postulated that ATP protects lysosomes by reducing an increase in intralysosomal concentration of KCl, which occurs when incubated lysosomes are exposed to hyperosmolar KCl.

scholarly journals Passive diffusion of non-electrolytes across the lysosome membrane

1989 ◽  
Vol 261 (2) ◽  
pp. 451-456 ◽  
Author(s):  
G P Iveson ◽  
S J Bird ◽  
J B Lloyd
Keyword(s):  
Hydrogen Bonding ◽  
Rat Liver ◽  
Liver Homogenate ◽  
Inverse Correlation ◽  
Protection Method ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes ◽  
Lysosome Membrane ◽  
Free Activity

An osmotic-protection method has been used to study the permeability of rat liver lysosomes to 43 organic non-electrolytes of formula weights ranging from 62 to 1000. A lysosome-rich centrifugal fraction of rat liver homogenate was resuspended in an unbuffered 0.25 M solution of test solute, pH 7.0, and incubated at 25 degrees C for 60 min. The free and total activities of 4-methylumbelliferyl N-acetyl-beta-D-glucosaminidase were measured after incubation for 0, 30 and 60 min. Three patterns of results were seen. In pattern A the percentage free activity remained low throughout the 60 min incubation, indicating little or no solute entry into the lysosomes. In pattern B, the percentage free activity was initially low, but rose substantially during the incubation, indicating solute entry. In pattern C there was not even initial osmotic protection, indicating very rapid solute entry. The rapidity of solute entry into the lysosomes showed no correlation with the formula weight, but a perfect inverse correlation with the hydrogen-bonding capacity of the solutes. The results, which can be used to predict the ability of further compounds to cross the lysosome membrane by unassisted diffusion, are discussed in the context of metabolite and drug release from lysosomes in vivo.

scholarly journals Isolation and Characterization of a Novel Membrane Glycoprotein of 85000 Molecular Weight from Rat Liver Lysosomes.

1992 ◽  
Vol 40 (1) ◽  
pp. 170-173 ◽  
Author(s):  
Kenji AKASAKI ◽  
Hiroko KINOSHITA ◽  
Masataka FUKUZAWA ◽  
Makoto MAEDA ◽  
Yasunori YAMAGUCHI ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Rat Liver ◽  
Membrane Glycoprotein ◽  
Isolation And Characterization ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes
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