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  • 1
    ISSN: 1432-1912
    Keywords: Sodium Lauryl Sulphate ; Ouabain ; Pralidoxime ; Phenolsulphonphthalein ; Jejunal Absorption ; Na-Dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In concentrations above the critical micelle concentration (effective range about 2 mM to about 22 mM) sodium lauryl sulphate caused graded increases in the absorption of ouabain, phenolsulphonphthalein and pralidoxime from jejunal loops in anaesthetized rats. The surfactant-caused increases in the absorption of phenolsulphonphthalein and pralidoxime were significantly reduced if the sodium chloride of the medium was replaced by mannitol, respectively sucrose, or by sodium phosphate, and also if ouabain was added to the medium. The extent in absorption in the absence of surfactant was not altered. The surfactant-caused increase in the absorption of ouabain was not reduced by the mentioned sodium chloride exchanges in the medium. It is suggested that the increased absorption caused by sodium lauryl sulphate must be ascribed to a direct effect on the intestinal membrane. The results indicate some kind of Na-dependence for the increase in absorption observed for phenolsulphonphthalein and pralidoxime. Additional studies are in progress to further elucidate the observations mentioned.
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  • 2
    ISSN: 1432-1912
    Keywords: Benzo(a)pyrene Hydroxylase ; Whole Implantation Site ; Decidua ; Placenta ; Fetal Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Treatment of pregnant rats with 40 mg benzo(a)pyrene (BP) per kg body weight p.o. 24 h prior to sacrifice results in an induction of BP hydroxylase activity in the whole implantation site, the decidua, the placenta, and the fetal membranes. In control animals, no enzyme activity can be measured in these tissues with the exception of the fetal membranes which occasionally have a very low BP hydroxylase activity. In the BP-treated rats the enzyme activity is at least 3 to 6 times higher in the fetal membranes than in the placenta. The disappearance rate of BP hydroxylase activity was measured in the whole implantation site for 48 h after treatment with 40 mg BP kg body weight on day 8 of gestation. In the whole implantation site, the maximum enzyme induction is observed within 18 h while 48 h after BP-treatment, the enzyme activity is very low. The disappearance rate of BP hydroxylase activity was also measured for 48 h in the placenta on day 12 and on day 19 of gestation, respectively. In the placenta the height of enzyme induction remains almost unchanged within a 48 h interval. After BP-treatment of rats, morphological alterations can be observed in the decidua which are characterized by a moderate enlargement of the vesicles of the rough endoplasmic reticulum while this treatment does not effect the fine structure of the fetal membranes.
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  • 3
    ISSN: 1432-1912
    Keywords: Schistosomiasis ; Tartar Emetic ; Lucanthone ; Niridazole ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Schistosomal infection in mice caused an inhibition of the hepatic drug metabolizing enzyme activities. The magnitude of inhibition was not the same for all enzyme activities measured. MMAA and paraoxon metabolizing activities were only moderately affected. Treatment of infected mice with schistosomicidal drugs produced a dramatic reversal of the inhibition in cases of MMAA and paraoxon metabolizing enzymes, the 2 activities mostly affected by schistosomal infection. On the other hand, the reversal of inhibition was not statistically significant in the other 2 enzyme activities. Comparing the effectiveness of the different schistosomicidal drugs in reversing the inhibition produced by schistosomal infection, lucanthone HCl was found to be inferior to the other drugs used, namely, tartar emetic, stibophen and niridazole.
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  • 4
    ISSN: 1432-1912
    Keywords: Botulinum Toxin ; β-Bungarotoxin ; Presynaptic Actions ; Low Calcium ; High Magnesium ; Effect of Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Comparison was made between the presynaptic actions of type A botulinum toxin (BoTX) and β-bungarotoxin (β-BuTX) on isolated nerve-muscle preparations. On the mouse and rat diaphragms, BoTX is about 100 and 10 times more potent than β-BuTX, respectively, whereas on the chick biventer cervicis muscle, β-BuTX is 3–10 times more potent. The paralytic actions of both toxins are preceded by latency, antagonized by high concentrations of calcium or magnesium and by deficiency of calcium, accelerated by high frequencies of nerve stimulation and retarded by decrease of temperature. The paralytic actions of BoTX as well as β-BuTX appear to take place in two processes: first, binding with their respective target sites and second, the inhibitory changes of the target macromolecule of the nerve terminals leading to failure of transmitter release. The latter process is not reversed by washing but is retarded greatly by low calcium, high magnesium or low temperature. Binding of β-BuTX is faster than that of BoTX. Miniature end-plate potentials of unreduced amplitude could be recorded in junctions blocked by either toxin. End-plate potentials were depressed and the successive decline of their amplitude during train of pulses was abolished by both toxins. In contrast to the initial facilitatory actions after β-BuTX, BoTX has no sign of facilitation such as increase of the frequency of miniature end-plate potential, restoration of neuromuscular transmission, increase of quantal content of end-plate potential and occurrence of spontaneous fasciculations in low calcium media. Another difference between the two toxins is the typical Wedensky inhibition on repetitive stimulation and post-tetanic potentiation in β-BuTX paralysed muscles. By contrast, after BoTX, sustained contraction without post-tetanic potentiation was observed. The two toxins show a mutual antagonism especially when β-BuTX is added before or simultaneously with BoTX. The action of the latter was completely antagonized in the presence of β-BuTX. Once it is bound to the target site, however, BoTX seems not to be antagonized by β-BuTX. On the other hand, BoTX appears to be able to retard the effect of bound β-BuTX.
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  • 5
    ISSN: 1432-1912
    Keywords: Cyclic AMP ; Cyclic GMP ; Swimming Stress ; Hypothermia ; Tyrosine Hydroxylase ; Adrenal Medulla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After male rats (100 g body weight) have completed 7 min of swimming at 15°C, their rectal temperature is decreased by 15°C. As expected, the increase of cAMP and the decrease of cGMP concentrations in adrenal medulla are delayed by the time period necessary for the body temperature to return to normal. Thus, taking into consideration the delaying effect of hypothermia, the swimming stress experiments are in agreement with the view that the enhancement of cyclic AMP/cGMP concentration ratios may function as the second messengers for the induction of tyrosine hydroxylase in adrenal medulla.
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  • 6
    ISSN: 1432-1912
    Keywords: 5-HT Synthesis Rate ; MAO Inhibitors ; Probenecid ; Ro4-4602 ; Tryptophan ; Brain ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-isotopic and isotopic methods were used to estimate the rate of 5-HT synthesis in the mouse brain. 5-HT and 5_HIAA levels were measured in tissues up to 10 min after the i. p. injection of pargyline (75 or 150 mg/kg) or pheniprazine (5 or 10 mg/kg) (5-HT and 5-HIAA, MAO-inhibitor methods). 5-HIAA levels were also estimated at various times after probenecid administration (200 or 400 mg/kg i. p.) (5-HIAA-probenecid method). 5-HTP levels were estimated at various times after the blockade of 5-HTP decarboxylase by Ro4-4602. (800, 1000 or 1200 mg/kg i. p.) (5-HTP method). Finally the rate of conversion of tryptophan into 5-HT has been estimated by measuring the initial accumulation of 3H-5-HT and 3H-5-HIAA in tissues following the intravenous injection of 3H-tryptophan (isotopic method). Rates of 5-HT synthesis obtained with the two MAO inhibitor methods were much higher (about 3 to 4 times) than those calculated with the 5-HTP and 5-HIAA-probenecid methods. An intermediate rate of 5-HT synthesis was found with the isotopic technique. The high rate of 5-HT synthesis observed with the 5-HT, MAO inhibitor method (about 8 nmoles/g/h) was not related to a stimulation of 5-HT synthesis. Differences seen with all methods are discussed with respect to results obtained by various groups of workers.
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  • 7
    ISSN: 1432-1912
    Keywords: Direct Lytic Factor ; Cobra Venom ; Phospholipase A ; Red Cells ; Haemolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of increasing the (colloid-)osmotic pressure in the extracellular medium on haemolysis by the direct lytic factor of cobra venom (DLF) and phospholipase A has been investigated. For comparison, N-ethyl-maleimide (NEM) and p-chloromercuribenzoate (p-CMB) were used. Dextran and sucrose abolished the haemolytic effect of NEM and p-CMB but reduced only slightly (dextran) or not (sucrose) the weak lytic activity of DLF. Haemolysis by phospholipase A in the presence of DLF, NEM or p-CMB was not significantly inhibited. Hypertonic NaCl solution considerably retarded the onset of haemolysis by DLF plus phospholipase A. The mean corpuscular volume of guinea-pig red cells increased slightly but definitely during incubation with DLF. It is concluded that the haemolytic effect of DLF has non-osmotic as well as osmotic components, and that phospholipase A causes non-osmotic haemolysis. The retardation of haemolysis by hypertonic NaCl probably indicates specific inhibition of bee venom phospholipase A2, not protection of the erythrocytes from osmotic stress.
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  • 8
    ISSN: 1432-1912
    Keywords: Isolated Perfused Rabbit Heart ; Phenylephrine ; dp/dt max ; Heart Rate ; Adrenolytic Drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the isolated perfused rabbit heart the effect of phenylephrine on the left ventricular dp/dt max and on heart rate was investigated. 1. The positive inotropic effect of phenylephrine 3×10−7 to 3×10−6 M was abolished by the α-adrenolytic drug phentolamine (3×10−6 M), whereas the β-adrenolytic drug pindolol (10−8 M) was ineffective. On the other hand, the positive inotropic effect evoked by higher concentrations (10−5 to 10−4 M) of phenylephrine was blocked by pindolol while phentolamine was without any effect. 2. The positive chronotropic effect of phenylephrine was antagonized by pindolol. Phentolamine was ineffective. 3. The results presented here show that the ventricular myocardium of the rabbit contains both β- and α-adrenoceptors responsible for the mediation of the positive inotropic effect of phenylephrine.
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  • 9
    ISSN: 1432-1912
    Keywords: Drug Metabolism ; Age ; Phenobarbital Treatment ; Liver Weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The developmental pattern of benzo(a)pyrene hydroxylase and ethylmorphine N-demethylase from 8 days before birth up to 100 days of age in rat liver homogenate was investigated. These two drug metabolizing enzyme reactions exhibited their highest activities at different times of hepatic development. Treatment with phenobarbital produces a selective effect on the magnitude of stimulation of these two enzyme reactions in rats of different ages. The higher levels of drug metabolizing enzyme activity after phenobarbital treatment were not always paralleled by higher liver weights. The duration of hexobarbital hypnosis was longer in young than in adult rats. However, after phenobarbital treatment hexobarbital effectiveness was decreased more in young than in adult rats.
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  • 10
    ISSN: 1432-1912
    Keywords: Kininogen ; Adrenaline ; Protease Inhibitor ; Granulocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Catecholamines lower the kininogen content of rat blood in vivo and in vitro. Blood cells are required: these are neither erythrocytes, lymphocytes, eosinophils nor platelets but could be neutrophils or basophils. The bovine protease inhibitor (Trasylol®) inhibits the effects of l-adrenaline in vivo and in vitro but fails to affect the action of cellulose sulfate on rat plasma kininogen by more than a small extent.
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