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  • Permeability  (3)
  • Pharmacokinetics  (3)
  • 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 273 (1972), S. 313-330 
    ISSN: 1432-1912
    Keywords: Snake Venom ; Phospholipase A ; Potentiation ; Iodine Labelling ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to obtain better insight into the potentiation of the toxicity of phospholipase A by crotapotin, we studied the distribution and elimination of these substances and of their combination. Blood Plasma Concentration. Iodine-labelled phospholipase A leaves the bloodstream of mice and rabbits very quickly after i.v. application. Simultaneous injection of crotapotin speeds the elimination of the enzyme. After subcutaneous application in mice the plasma concentration of phospholipase A depends on the quantity of enzyme injected. It is higher when the enzyme is complexed with crotapotin before injection. The plasma concentration of phospholipase A fails, however, to be proportional to the toxicity of the complex after subcutaneous application. Crotapotin leaves the blood of mice also very quickly after i.v. application. Organ Distribution. After i.v. application in mice, phospholipase A is heavily enriched in the liver. By simultaneous application of crotapotin, the enzyme is partially diverted to the kidneys. Only a small percentage of injected enzyme is found in the brain. This percentage is just significantly raised by simultaneous application of crotapotin. The diaphragm contains about the twofold amount of phospholipase A per wet weight as compared with other samples of skeletal musculature. With crotapotin, there is a slight increase of the radioactivity in all muscles investigated, with different degrees of significance. Crotapotin is enriched in mouse kidneys after i.v. application. Renal Elimination. The renal elimination of the acidic crotapotin is higher than that of the basic phospholipase A. In this respect, the latter resembles the basic polypeptide Trasylol®. Doses of phospholipase A above 0.25 mg/kg cause intravital hemolysis. The hemolysis is prevented if a small amount of crotapotin is applied simultaneously. Our findings show that the combination with crotapotin distinctly alters the pharmacokinetic behaviour of Crotalus terrificus phospholipase A. However, our data do not explain the tremendous increase of phospholipase A toxicity caused by the non-toxic crotapotin.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 276 (1973), S. 327-340 
    ISSN: 1432-1912
    Keywords: Tetanus Toxin ; Pharmacokinetics ; Central Nervous System ; Iodine Labelling ; Receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to understand the symptomatology of generalized tetanus from the pharmacokinetics of the toxin, 125I-labelled toxin was injected i.v. in rats without and with antitoxin. 1. After a few hours latency, brain stem and spinal cord concentrate radioactive material up to the third day. The decline of radioactivity is very slow, semilogarithmic, and can be followed up to the 24th day after injection. In contrast, forebrain and cerebellum do not bind measurable radioactivity. Less than 1% of the radioactivity injected is found in the CNS. 2. The symptoms of tetanus start some time after the bulk of labelled toxin has been taken up by the CNS. They cease before all radioactivity has left it. 3. Antitoxin, given simultaneously, prevents the onset of symptoms and the uptake of radioactivity by the CNS. When given 10 h after labelled toxin, it nearly abolishes the fixation and still prevents the onset of symptoms. When given 48 h after toxin, it is nearly ineffective in both respects. Antitoxin first delays, then enhances the elimination of labelled toxin from the blood. 4. Labelled antitoxin is not enriched in the CNS. 5. The uptake of radioactivity into various parts of spinal cord corresponds well to their relative content in grey matter. 6. The pharmacokinetic behaviour of 125I-toxoid resembles that of toxin. However, in order to get measurable fixation to the CNS at least 50 times higher amounts are to be applied. It is concluded that the barrier between blood and CNS is practically impermeable to tetanus toxin. The results can be harmonized best with the assumption that generalized tetanus is nothing else than a multiple local tetanus.
    Type of Medium: Electronic Resource
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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 299 (1977), S. 187-196 
    ISSN: 1432-1912
    Keywords: Tetanus ; Iodine labeling ; Spinal cord ; Metabolism ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Local tetanus was elicited in rats and cats by intramuscular injection of 125I-tetanus toxin. After different times spinal radioactivity was extracted with either non-ionic (Lubrol PX) or ionic (sodium dodecyl sulfate, SDS) detergents and compared with native or 125I-toxin by gel filtration, SDS-gel electrophoresis, immunological procedures, and toxicity tests. In double-isotope experiments, 131I-toxin was added to the extracts as standard. In rats, the bulk of extracted material was indistinguishable from native toxin. However, there was a slight shift of the extracted material towards smaller molecular weights in gel filtration with Lubrol. In gel filtration with SDS, the toxin peak was followed by some tailing of 125I radioactivity. Accordingly a small part of extracted radioactivity moves faster than the standard in SDS disc gel electrophoresis. These findings taken together indicate some degradation in vivo. Adsorption to solid-phase antibodies indicated that more than 80% of the radioactivity extracted from rats was still immunoreactive. It yielded a zone confluent with extrinsic toxin in immunodiffusion. The spinal cord Lubrol extract from rats was still toxic in the expected range. Due to the very small amounts of toxin present, no precise toxicity data could be given. In cats, there was also some evidence for radioactive split products in both SDS gel filtration and disc gel electrophoresis. The patterns closely resembled those obtained with extracts from rat spinal cord. SDS extracts from rat and cat spinal cords, poisoned with 125I tetanus toxin in vivo, were also subjected to SDS disc gel electrophoresis followign reduction with dithioerythritol (DTE). They yielded large and small chains of the same size as did native toxin. In vitro, extensive degradation with brain homogenate from rats took place at pH 3.65, but not at pH 7.5. This indicates that lysosomal degradation is not a major metabolic pathway of tetanus toxin in vivo, although it is possible in principle. It is concluded that a) unlike other toxins, tetanus toxin is not necessarily degraded during its cellular uptake, b) the bulk of radioactive material is indistinguishable, following its neuronal ascent, from native or labeled toxin, c) a part of the radioactivity is recovered as split products.
    Type of Medium: Electronic Resource
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