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  • 1
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The activities of menthol and peppermint oil were determined in guinea-pig ileal smooth muscle, in rat and guinea-pig atrial and papillary muscle, in rat brain synaptosomes and in chick retinal neurones by pharmacological 45Ca2+ uptake and radioligand binding assays. Menthol is a major constituent of peppermint oil and is approximately twice as potent as peppermint oil as an inhibitor of K+ depolarization-induced and electrically stimulated responses in ileum and electrically stimulated atrial and papillary muscles. IC50 values in the ileal preparation ranged from 7.7 to 28.1 μg ml−1 and in the cardiac preparations from 10.1 to 68.5 μg ml−1. Similar potencies were demonstrated against K+ depolarization-induced 45Ca2+ uptake in synaptosomes and against K+ depolarization and Bay K 8644-induced uptake in chick retinal neurons. IC50 values for menthol inhibition of K+ and Bay K 8644 responses in the retinal neurons were 1.1 × 10−4 M (17.2 μg ml−1) and 1.75 × 10−4 M (26.6 μg ml−I), respectively, and for peppermint oil were 20.3 and 41.7 μg ml−1 respectively. Both menthol and peppermint oil inhibited specific [3H]nitrendipine and [3H]PN 200–110 binding to smooth and cardiac muscle and neuronal preparations with potencies comparable to, but slightly lower than, those measured in the pharmacological and 45Ca2+ uptake experiments. Binding of menthol and peppermint oil, studied at 78 μg ml−1, was competitive against [3H]nitrendipine in both smooth muscle and synaptosome preparations. The data indicate that both menthol and peppermint oil exert Ca2+ channel blocking properties which may underlie their use in irritable bowel syndrome. Ca2+ channel antagonism may not be the only pharmacological effect of menthol and peppermint oil contributing to intestinal smooth muscle relaxation.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 15 (1987), S. 35-37 
    ISSN: 1434-0879
    Keywords: Prostatic hyperplasia ; 5-Fu ; Medical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A prospective study of 5-Fu in the treatment of prostatic hyperplasia was commenced in 1981. The short term results were fair in 70% of 43 patients. Atrophy of the glandular tissue could be observed on histopathologic examinaion. The study showed that the larger the glandular component the better was the therapeutic effect. If abundant fibromuscular tissue was present in the gland the treatment was unsatisfactory. Abnormal anatomy of the bladder neck, represented a contraindication to medical treatment.
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  • 3
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1912
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 5
    ISSN: 1432-1912
    Keywords: Ca2+ ; Ca2+ channels ; Ca2+ channel antagonists ; 1,4-Dihydropyridines ; [3H]PN 200-110
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Ca2+ channel antagonistic potencies of tiamdipine [2-(2-aminoethylthio)methyl-3-carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine] and nifedipine [2,6-dimethyl-3,5-dicarbomethoxy-4-(2nitrophenyl)-1,4-dihydropyridine] analogs bearing phenyl ring substituents were studied using pharmacologic and radioligand binding techniques. Additionally, analogs of tiamdipine possessing (2-aminoethylthio)methyl-, (2-acetamidoethylthio)methyl-and (2-pyrrolidinylmethylthio)methyl-groups at the C2 position of the 1,4-dihydropyridine ring have been studied. Tiamdipine and nifedipine analogs inhibited K+-induced contractile responses in rat tail artery. IC50 values of 4-phenyl ring substituted 2-(2-aminoethylthio)methyl tiamdipine analogs ranged from 10−7 mol/l to 10−8 mol/l. However, the corresponding 4-phenyl ring substituted nifedipine analogs covered a wider range of potency from 10−6 mol/l to 10−9 mol/l. K, values of the corresponding tiamdipine analogs for the inhibition of specific [3H]PN 200-110 [( I- ) [3H]isopropyl-4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-5-methoxycarbonyl-2,6-dimethyl-3-pyridinecarboxylate] binding-ranged from 10−7 mol/l to 10−9 mol/l in guinea pig ileal and rat heart membranes and rat brain synaptosomes. The two stereoisomers of tiamdipine and its analog 2-(2acetamidoethylthio)methyl-3-carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine, and the four stereoisomers of 2-(2-pyrrolidinylmethylthio)methyl-3carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)1,4-dihydropyridine showed high stereoselectivity ratios of approximately (−)/(+) = 100 and 1000 in pharmacologic and binding experiments, respectively. The inhibitory actions of 2-(2-aminoethylthio)methyltiamdipine analogs against K+-induced contractile responses in rat tail artery developed very slowly requiring at least 2 h for maximum effect. The recoveries of response to K+ depolarization were also correspondingly slow. However, recovery was greatly accelerated by the presence of the 1,4-dihydropyridine activator Bay K 8644 [2,6-dimethyl-3carbomethoxy-5-nitro-4-(2-trifluoromethyl)-1,4-dihydropyridine, 5 × 10−6 mol/l] immediately prior to the K+ challenge. The 2-(2-acetamidoethylthio)methyl tiamdipine derivative and nifedipine produced maximum inhibitory effects within 10 min, and responses recovered rapidly upon washing. The slow kinetics of onset and offset of action of the tiamdipine analogs and the reduced effects of 4-phenyl substitution relative to agents of the nifedipine series suggest that these two series of 1,4-dihydropyridines exhibit different modes of interaction with the Ca2+ channel. At least part of this difference is to be attributed to the presence of a charged group in the basic tiamdipine series. Trapping of these agents within the membrane phase likely contributes to their observed slow kinetics of action.
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  • 6
    ISSN: 1432-1912
    Keywords: Calcium channels ; β-Adrenoceptors ; Cardiac ; Hyperthyroidism ; Hypothyroidism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To determine the influence of thyroid hormone on β-adrenoceptors and Ca2+ channels, rats were treated with thyroxine (75 μg/100 g sc daily for 5 days) or propylthiouracil (0.05% in drinking water for 30 days). β-Adrenoceptor density in ventricular tissue, measured by [125I]iodocyanopindolol binding, was significantly increased and decreased respectively, following thyroxine or propylthiouracil treatment to 124.7 ± 7.11 fmol/mg protein and 71.98 ± 5.37 fmol/mg protein from euthyroid (control) levels of 93.7 ± 4.58 fmol/mg protein. Ca2+ channel density, measured by [3H]nitrendipine binding, was altered in the opposite direction; it was significantly decreased and increased to 324 ± 24 fmol/mg protein and 691 ± 31 fmol/mg protein from 562 ± 35 fmol/mg protein after thyroxine or propylthiouracil treatment, respectively. No changes in affinity of either ligand were observed. Responses of isolated papillary muscles from propylthiouracil-treated animals accorded with changes seen in the binding studies. The geometric mean EC50 of isoproterenol increased from 9.5 × 10−9 mol/1 to 5.5 × 10−8 mol/l, and the EC50 for calcium decreasedfrom 3.16 × 10−3 mol/1to 1.36 × 10−3 mol/1; moreover, the responsiveness to the Ca 2+ channel activator Bay K 8644 was increased. The corresponding responses in thyroxine-treated animals could not be examined because of prominent arrhythmic activity. As with papillary muscles the sensitivity of left atria to isoproterenol was decreased after treatment with propylthiouracil, with geometric mean EC50 values increasing from 3.21 × 10−9 mol/1 to 89.4 × 10−9 mol/l. This was however, associated with a decrease in the sensitivity to calcium with geometric mean EC50 values increasing from 2.43 × 10−3 mol/1 to 5.33 × 10−3 mol/1 and a reduction in the maximal response to Bay K 8644. Treatment with thyroxine had no effect on tissue sensitivity. The responses of isolated tail artery to phenylephrine, calcium and Bay K 8644 were not significantly different in propylthiouracil- or thyroxine-treated animals.
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