scholarly journals Effect of a transitory ischaemia on the structure-linked latency of rat liver acid phosphatase and β-galactosidase

1981 ◽  
Vol 196 (3) ◽  
pp. 861-866 ◽  
Author(s):  
R Wattiaux ◽  
S Wattianx-De Coninck
Keyword(s):  
Blood Flow ◽  
Acid Phosphatase ◽  
Distribution Pattern ◽  
Rat Liver ◽  
Differential Centrifugation ◽  
Liver Lysosomes ◽  
Secondary Rise ◽  
Beta Galactosidase ◽  
Free Activity ◽  
Normal Latency

The structure-linked latency of acid phosphatase and beta-galactosidase was studied in rat liver lobes made ischaemic for 1 or 2 h and then recirculated with blood for increasing periods. Free activity of acid phosphatase and unsedimentable activity of beta-galactosidase are increased in homogenates of ischaemic livers. When ischaemia had been maintained for 1 h, the recovery of normal latency for both enzymes was observed 1 h after re-establishment of the blood flow. After a 2 h period of ischaemia, unmasked activity markedly decreases during the first 1 h after restoration of blood flow; after that, a large and irreversible secondary rise takes place. Chlorpromazine, injected 30 min before or just after induction of ischaemia, extensively prevents the latency decrease occurring during restoration of blood flow. Modifications of the hydrolase distribution pattern obtained after differential centrifugation are in agreement with the latency changes. These results suggest that a 2 h ischaemia causes an alteration of the liver lysosomes that is largely reversible and that restoration of blood flow induces an irreversible alteration of these organelles. Chlorpromazine treatment prevents the irreversible lesion from taking place.

Isolation and sequencing of a cDNA clone encoding acid phosphatase in rat liver lysosomes

1989 ◽  
Vol 162 (3) ◽  
pp. 1044-1053 ◽  
Author(s):  
Masaru Himeno ◽  
Hideaki Fujita ◽  
Youichiro Noguchi ◽  
Akira Kono ◽  
Keitaro Kato
Keyword(s):  
Acid Phosphatase ◽  
Rat Liver ◽  
Cdna Clone ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes

scholarly journals Further observations on the activation of lysosomal acid α-glucosidase by cortisone derivatives

1973 ◽  
Vol 132 (3) ◽  
pp. 435-438 ◽  
Author(s):  
E. J. Bourne ◽  
K. Clarke ◽  
J. B. Pridham ◽  
J. J. M. Rowe
Keyword(s):  
Acid Phosphatase ◽  
Rat Liver ◽  
Lysosomal Membrane ◽  
Cortisone Acetate ◽  
Lysosomal Acid ◽  
Liver Slices ◽  
Liver Lysosomes ◽  
Membrane Bound ◽  
Isolated Liver

1. Cortisone acetate activates the acid α-glucosidase in rat liver slices and in isolated liver lysosomes. 2. The reaction is steroid specific and moreover does not occur with lysosomal acid phosphatase or β-galactosidase. 3. After pretreatment of the lysosomes with cortisone, substrate (maltose) binding to the soluble lysosomal acid α-glucosidase is not affected, but the steroid does increase the Vmax. value. Membrane-bound enzyme is not activated by cortisone. 4. 4-[14C]Cortisone is preferentially bound to the lysosomal membrane and the possible involvement of this structure in the activation phenomenon is discussed.

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.

Effect of Glycyrrhizin on Lysosomes Labilization by Phospholipase A2

1986 ◽  
Vol 14 (03n04) ◽  
pp. 131-137 ◽  
Author(s):  
Yasuko Shiki ◽  
Yo Ishikawa ◽  
Kohji Shirai ◽  
Yasushi Saito ◽  
Sho Yoshida
Keyword(s):  
Acid Phosphatase ◽  
Phospholipase A2 ◽  
Rat Liver ◽  
Lysosomal Membrane ◽  
Phospholipase A ◽  
Ph Optimum ◽  
Liver Lysosomes ◽  
Inhibited Acid ◽  
Rat Liver Lysosomes

The influence of glycyrrhizin on the effect of phospholipase A2 on lysosomes was studied. Treatment of rat liver lysosomes with venom phospholipase A2 caused release of acid phosphatase. This release of acid phosphatase was inhibited by 0.1 mM glycyrrhizin. Glycyrrhizin also inhibited acid phospholiase A2 with pH optimum of 4.5, which is thought to be present in the lysosomal membrane. These results suggests that glycyrrhizin stabilizes lysosomes by inhibiting phospholipase A2 activity in the lysosomal membrane.

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.

Liver Blood Flow as a Major Determinant of the Clearance of Recombinant Human Tissue-Type Plasminogen Activator

1992 ◽  
Vol 67 (01) ◽  
pp. 083-087 ◽  
Author(s):  
A de Boer ◽  
C Kluft ◽  
J M Kroon ◽  
F J Kasper ◽  
H C Schoemaker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rat Liver ◽  
Healthy Subjects ◽  
Liver Blood Flow ◽  
Major Determinant ◽  
Tissue Type ◽  
Perfused Rat Liver ◽  
Liver Model ◽  
Type Plasminogen Activator ◽  
Proportional Change

SummaryThe influence of changes in liver blood flow on the clearance of rt-PA was studied both in healthy subjects and in a perfused rat liver model. Liver blood flow in healthy subjects was documented indirectly by the clearance of indocyanine green (ICG). Exercise reduced liver blood flow on average by 57% with a 95% confidence interval (95% Cl) ranging from 51% to 62% (n = 5) and increased plasma levels of rt-PA activity (after an i. v. infusion of 18 mg of rt-PA over 120 min) by 119% (95% Cl, 58% - 203%) and rt-PA antigen by 91% (95% Cl, 30% - 140%). In the perfused rat liver model it was shown that halving or doubling of the physiological flow rate of a perfusate, containing rt-PA caused a proportional change in the clearance of rt-PA, while the extraction of rt-PA by the liver remained similar. In conclusion, liver blood flow is a major determinant of the clearance of rt-PA. This may have important implications for dosage of rt-PA in patients with myocardial infarction.

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