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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 688 (1982), S. 486-494 
    ISSN: 0005-2736
    Keywords: (Erythrocyte) ; Amphotericin B ; Palytoxin ; Permeability
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 300 (1977), S. 67-76 
    ISSN: 1432-1912
    Keywords: Polycations ; Aminoglycosides ; Kidney ; Brush border membrane ; Lysosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Experiments with Brush Border Membranes Drugs were screened for inhibition of 125I-aprotinin binding to isolated rat renal brush border membranes. Cationic polymers were effective, and their primary amino groups were crucial. The polycationic aminoglycosides displaced 125I-aprotinin with low concentrations (50% inhibition by 50 μg/ml of gentamicin). The decreasing sequence of both number of amino groups and of inhibitory potency was: neomycin 〉 tobramycin 〉 gentamicin 〉 kanamycin 〉 streptomycin. Binding of 3H-gentamicin-C1 to the brush border membrane was saturable. The Scatchard plot indicated an association constant of 43 mM−1, and 18 nmoles per mg of membrane protein for the number of binding sites. Inhibition of 125I-aprotinin binding by gentamicin was competitive. The inhibition constant (KI) was 20 μg/ml with concentrations of 8 and 40 μg/ml of gentamicin. 2. Experiments with Lysosomes Gentamicin and aprotinin (200 μg/ml) activated β-glucuronidase and β-galactosidase from renal lysosomes, but not acid phosphatase. Gentamicin and aprotinin (300 μg/ml) increased the release of acid phosphatase from intact renal lysosomes. Lysosomal degradation of 125I-aprotinin into acid soluble split products was much slower than that of 125I-insulin. From our present and previous results it is concluded that binding to the brush border membrane occurs with chemically quite different, however basic drugs and that the number of amino groups per molecule is relevant. Nephrotoxicity of aminoglycosides may be related to their endocytic uptake through a direct action on lysosomes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 319 (1982), S. 101-107 
    ISSN: 1432-1912
    Keywords: Palytoxin ; Ouabain ; Erythrocytes ; Permeability ; ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Palytoxin in concentrations as low as 1 pM raises the potassium permeability of rat, human and sheep erythrocytes, and the sodium permeability of human erythrocytes. The release of potassium or sodium from human cells also occurs when extracellular sodium is replaced by choline. 2. Ouabain inhibits the release due to palytoxin of potassium ions from human, sheep and rat erythrocytes, and also the release of sodium ions from human cells. The glycoside effect is specific since a) it is already prominent with 5×10−8 M ouabain b) rat erythrocytes are less sensitive than human cells to ouabain c) potassium release due to amphotericin B or the Ca2+ ionophore A23187 is not influenced by ouabain and d) dog erythrocytes are resistant to palytoxin as well as to ouabain. 3. Palytoxin has no direct influence on the Na+, K+-ATPase. It inhibits the binding of [3H]ouabain to erythrocyte membranes within the same concentration range as unlabelled ouabain. It partially displaces bound [3H]ouabain, and partially inhibits the inactivation of erythrocyte ATPase by the glycoside. Depletion of ATP or of external Ca2+ renders the cells less sensitive to palytoxin. Nevertheless inhibition by ouabain can be still demonstrated with human cells whose ATP stores had been largely exhausted, and also in the absence of external Ca2+. 4. Palytoxin decreases the surface tension at the air-water interface. We assume that the formation of nonspecific pores by palytoxin is linked with its surface activity. Further experiments should demonstrate whether ouabain prevents the binding of palytoxin to erythrocytes (“receptor hypothesis”), or whether an ouabain-sensitive hydrolysis of trace amounts of ATP (“metabolic hypothesis”) promotes the palytoxin effect.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 264 (1969), S. 476-493 
    ISSN: 1432-1912
    Keywords: Kinins ; Permeability ; Heat ; Inflammation ; Kinine ; Permeabilität ; Hitze ; Entzündung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The suboutis of rat paws heated (46,5° C) in situ has been perfused. Kinin activity could be demonstrated regularly in the fluid which was collected in ice. When the solutions were tested immediately after having passed the tissue, only some of the experiments yielded positive results. Native and125Jlabelled kininogen as well as kininogenase and kininase activities passed into the perfusates. The sensitivity to dextran and the kinin release on heating were, in contrast to recent reports, not correlated. 2. The release of the components of the kinin system approximately paralleled that of labelled human albumin. Their concentration rose until about 1 hour after the start of the heating. There was no priority of the components of the kinin system when compared with human albumin which can be regarded as permeability indicator. 3. Intravenously injected carboxypeptidase B, because of its lower molecular weight, entered the interstitial fluid more easily than did the plasma carboxypeptidase N. Its blood level decreased rapidly; but sufficient tissue concentrations could be maintained by intravenous infusions. Neither the volume nor the time dependence of the thermic edema changed during carboxypeptidase B-infusions. The same was true for infusions of trasylol, whereas phenylbutazone inhibited the edema significantly. Edema formed by short heating (30 sec, 55° C) was equally resistant to carboxypeptidase B. 4. In the skin and muscles of the heated rat paw, carbon particles mainly stained the capillary walls. This finding argues against a considerable involvement of “classical” mediators which should induce venular lesions. 5. Infusion of large amounts of bradykinin into the arterial supply did not imitate the thermic edema; neither has bradykinin been found in the perfusate of the subcutis. 6. In the light of these findings, a significant role of the kinin system in the thermic edema of the rat paw is to be doubted.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 300 (1977), S. 57-66 
    ISSN: 1432-1912
    Keywords: Aminoglycoside ; Gentamicin ; Kidney ; Electron microscopic autoradiography ; Lysosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Upon intravenous injection of 3H-gentamicin in rats, radioactivity in serum rapidly declined to 3% of total within 1 h. Kidneys accumulated a constant amount (14%) of the injected radioactivity between 2 and 6 h after injection. In mice, simultaneous or prior application of unlabeled gentamicin (10 mg/kg) diminished the renal concentration of 3H-gentamicin, and aprotinin (10 mg/kg) was able to compete with labeled aprotinin. Aprotinin did not diminish the renal accumulation of gentamicin and vice versa. However, since 10 mg/kg aprotinin raised also the plasma concentrations of both 3H-gentamicin and 125I-aprotinin, the evidences resulting from these experiments are limited. Mouse kidney cortex was processed for light and electron microscopic autoradiography at different times following i.v. injection of 3H-gentamicin. Gentamicin enters the apical part of proximal tubule cells. Initially, brush border and basement membrane labeling is prominent, whereas lysosomes appear as intense and prevalent stores 20 min or later after injection. Fractionation of 3H-gentamicin loaded kidneys showed a similar distribution pattern of radioactivity and the lysosomal marker β-galactosidase. The same was true when the crude lysosomal fraction was subjected to density gradient centrifugation, which corroborates the microscopical findings. Radioactivity is partially bound to lysosomal structures, for repeated freezing of loaded lysosomes left 35% of radioactivity particle-bound. It is concluded that both gentamicin and peptides are handled in a similar manner by adsorption, followed by endocytosis and lysosomal sequestration in proximal tubule cells.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 325 (1984), S. 85-87 
    ISSN: 1432-1912
    Keywords: Na+, K+-ATPase ; Palytoxin ; Ouabain ; Kidney ; Erythrocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hog kidney Na+, K+-ATPase, purified to the microsomal stage and activated with detergent, binds palytoxin, as shown by the nearly complete competition of the toxin with 3H-ouabain. The K i-values of palytoxin, but not of ouabain, depend on the protein concentration; this indicates additional binding sites for the toxin on kidney membranes. — Palytoxin inhibits the enzymatic activity of the detergent-activated preparation nearly completely (IC50 8·10−7 mol/l). Inhibition of ATPase activity and of ouabain binding are promoted by borate, a known activator of palytoxin. — Palytoxin also inhibits the Na+, K+-ATPase of erythrocyte ghosts in the same dose range. The data are discussed in context with the hypothesis (Chhatwal et al. 1983) that palytoxin raises the cellular permeability by altering the state of Na+, K+-ATPase or its environment.
    Type of Medium: Electronic Resource
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