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  • 1
    Electronic Resource
    Electronic Resource
    Adult free zones in small mammal populations: response of Australian native rodents to reduced cover (2005)
    Melbourne, Australia : Blackwell Science Pty
    Austral ecology 30 (2005), S. 0 
    Details
    ISSN: 1442-9993
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract  Cover provides shelter, food, nesting opportunities and protection from predators. The behavioural response of small mammals to reduced cover has been well documented. However, very little is known about the effect of cover on community and population dynamics. Australian small mammals generally inhabit extremely dynamic ecosystems, where cover and food supplies are greatly affected by fire. Species are described as early or late seral specialists, generally returning to a disturbed area once their habitat requirements are met. Habitat requirements have loosely been interpreted as cover and food supply, however, these factors are not mutually exclusive and few studies have attempted to determine the driving factors behind small mammal succession. In this study, we manipulated specific aspects of cover in the eucalypt forests of Fraser Island and show that the behaviour and population dynamics of small mammals were greatly affected. A reduction of cover from grass-trees (Xanthorrhoea johnsonii) did not affect small mammal species composition, however, the abundance and size structure distribution of the dominant species (Rattus fuscipes) decreased. Patch use by rodents also decreased after cover was reduced. Rattus fuscipes must trade-off remaining in an environment with increased risk of predation, or disperse to an area with greater cover but increased competition. Juveniles dominated (〉60%) populations of R. fuscipes after cover was reduced, however, size distributions of control sites were relatively more even (〈25% juvenile). While adult R. fuscipes are either killed by predators or disperse to other areas, juveniles that remained or immigrated to an area of reduced cover gained a selective advantage over those in control sites, because reduced competition with adults increased body condition of juvenile R. fuscipes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1442-9993.2005.01530.x
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  • 2
    Electronic Resource
    Electronic Resource
    5-Hydroxytryptamine4 receptors mediate relaxation of the rat oesophageal tunica muscularis mucosae (1991)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 343 (1991), S. 439-446 
    Details
    ISSN: 1432-1912
    Keywords: 5-HT4 ; Oesophagus ; Rat ; ICS 205–930 ; Benzamides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study was designed to characterize an “atypical” 5-hydroxytryptamine (5-HT) receptor mediating relaxation of the rat oesophageal tunica muscularis mucosae. All experiments were performed under equilibrium conditions, using pargyline to inhibit the oxidative deamination of indoleamines, and cocaine and corticosterone to inhibit neuronal and extraneuronal uptake. Under these conditions 5-HT (0.3–1000 nmol/l) produced a concentration-dependent relaxation of carbachol-induced tension. The concentration-effect curve to 5-HT was unaffected by potent antagonists for 5-HT1, 5-HT2, 5-HT3 and so called 5-HT1P receptors (metergoline, methysergide, ketanserin, ondansetron, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide), but was antagonized competitively by ICS 205–930 (pA2 = 6.7). Responses to 5-HT were mimicked by other indoleamines and substituted benzamides with the following order of potency: 5-HT ≥ 5-methoxytryptamine 〉 cisapride = α-methyl-5-HT = (S)-zacopride = renzapride 〉 (RS)-zacopride 〉 5-carboxamido-tryptamine = metoclopramide = (R)-zacopride 〉 tryptamine 〉 2-methyl-5-HT. ICS 205–930 afforded similar pA2 values (6.0–6.7) against each agonist, indicating a common site of action. Concentration-effect curves to 5-HT were not affected by tetrodotoxin or indomethacin, sugesting that 5-HT-induced relaxation of the tunica muscularis mucosae was mediated via a postjunctional receptor, independent of endogenous prostanoids. The pharmacological profile of the 5-HT receptor in the rat oesophageal tunica muscularis mucosae correlates well with the 5-HT4 receptor characterized recently in both the CNS and gastro-intestinal tract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169544
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  • 3
    Electronic Resource
    Electronic Resource
    BRL 46470A: a highly potent, selective and long acting 5-HT3 receptor antagonist with anxiolytic-like properties (1993)
    Springer
    Psychopharmacology 110 (1993), S. 257-264 
    Details
    ISSN: 1432-2072
    Keywords: Anxiolytic ; 5-HT3 receptors ; Social interaction ; X-maze ; Bezold-Jarisch reflex ; BRL 46470A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The novel 5-HT3 antagonist, BRL 46470A (endo-N-(8-methyl-8-azabicyclo [3.2.1]oct-3-yl)2,3-dihydro-3,3 dimethyl-indole-1-carboxamide, hydrochloride), has been investigated in a series of in vitro and in vivo tests, including the effect of the drug in models of anxiolysis. In classical tests for 5-HT3 receptor antagonism, BRL 46470A was shown to antagonise 5-HT3 mediated responses in the guinea-pig ileum [pA2 8.3±0.5, slope 0.98±0.20, mean±SEM (5)], the rabbit isolated heart (pA2 10.1±0.1, slope 1.2±0.2,n=5) and the rat Bezold-Jarisch model (ID50 0.7 µg/kg IV±0.1,n=8), with a long duration of action (〉3 h). BRL 46470A selectively displaced [3H]-BRL 43694 from 5-HT3 binding sites in rat brain membranes (Ki 0.32 nM±0.04,n=4) without displacing (at concentrations greater than 1 µM) a wide variety of ligands binding to other neurotransmitter receptors, opioid receptors and to neurotransmitter gated ion channel complexes. In vivo, BRL 46470A showed anxiolytic-like activity in two animal models predictive of antianxiety effects-elevated X-maze and social interaction in rats. In both models, BRL 46470A showed significant activity over a wide dose-range following both oral (0.0001–0.1 mg/kg PO) and systemic administration. The unique level of potency of BRL 46470A was apparent in the rat social interaction test and was shown to be 100 fold more potent than the 5-HT3 receptor antagonist ondansetron, with no evidence of a bell-shaped dose response curve over 4 orders of magnitude. BRL 46470A (0.0001 and 0.01 mg/kg SC) also reduced the anxiogenic effects of m-CPP (1-(3-chlorophenyl) piperazine) in the rat elevated X-maze. BRL 46470A is therefore a chemically novel potent and selective 5-HT3 receptor antagonist with anxiolytic potential and a long duration of action in animal studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02251279
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    Paper (German National Licenses)
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