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.

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.

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 Genistein inhibits glucose and sulphate transport in isolated rat liver lysosomes

2009 ◽  
Vol 103 (2) ◽  
pp. 197-205 ◽  
Author(s):  
Hsu-Fang Chou ◽  
Kun-Hung Chuang ◽  
Yi-Shan Tsai ◽  
Yi-Ju Chen
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Rat Liver ◽  
Uptake Kinetics ◽  
Isolated Rat Liver ◽  
Sulphate Transport ◽  
Genistein Treatment ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes ◽  
Isolated Rat

Genistein and daidzein are known to have both beneficial and adverse effects on human health due to their many biological actions at the cellular level. Both isoflavones have been shown to inhibit GLUT-mediated glucose transport across the plasma membrane of mammalian cells. Since lysosomal membrane transport is essential for maintaining cellular homeostasis, the present study examined the effects of genistein and daidzein on glucose and sulphate transport in isolated rat liver lysosomes. Both genistein and daidzein significantly inhibited lysosomal glucose uptake. Genistein was a more potent glucose transport inhibitor than daidzein, with a half-maximum inhibitory concentration (IC50) of 45 μmol/l compared with 71 μmol/l for daidzein. Uptake kinetics of d-glucose showed a significant decrease in Vmax (control:genistein treat = 1489 (sem 91):507 (sem 76) pmol/unit of β-hexosaminidase per 15 s) without a change in Km. The presence of 50 μm-genistein in the medium also reduced glucose efflux from lysosomes preloaded with 100 mm-d-glucose. Genistein also inhibited lysosomal sulphate transport. Similar to its effects on glucose uptake kinetics, genistein treatment caused a significant decrease in sulphate uptake Vmax (control:genistein treat = 87 (sem 4):59 (sem 5) pmol/unit of β-hexosaminidase per 30 s), while the Km was not affected. The evidence provided by the present study suggests that the most likely mechanism of lysosomal glucose transport inhibition by genistein is via direct interaction between genistein and the transporter, rather than mediation by tyrosine kinase inactivation. Genistein likely has a similar mechanism of directly inhibiting sulphate transporter.

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 Interaction of salicylates with rat liver lysosomes

1969 ◽  
Vol 115 (5) ◽  
pp. 54P-54P ◽  
Author(s):  
D Robinson ◽  
P Willcox
Keyword(s):  
Rat Liver ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes
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