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  • 1
    Electronic Resource
    Electronic Resource
    Modulation of plasma melatonin concentrations by changes in posture (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 24 (1998), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Posture change from a lying position to a standing position results in a decrease in plasma volume, which leads to an increase in plasma constituents, especially that of proteins and blood constituents bound to them. The aim of the present study was to investigate the physiological effects of postural changes on plasma nocturnal melatonin concentrations in healthy human volunteers. The study was divided into four stages. During stage one, subjects were seated from 21.00 hr to 01.00 hr. In stage two, subjects were lying at ground level from 21.00 hr to 01.00 hr. In stage three, subjects were is a sitting position from 2100 hr to 2300 hr and then in a standing position from 23.00 hr to 24.00 hr, and back to the sitting position from 24.00 hr to 01.00 hr. In the final stage, subjects were in a lying position from 21.00 hr to 23.00 hr and then in a standing position from 23.00 rh to 24.00 hr and back to the lying position from 24.00 hr to 01.00 hr. AUC analysis showed significant differences between sitting and lying positions (t=2.84; P〈0.05; df=5), with higher melatonin levels associated with the sitting position (mean difference in peak concentration of 17.1 pg/ml). Furthermore a change in posture from the lying to the standing position produced a statistically significant increase in melatonin concentrations (final stage) (t=−3.37; P〈0.05; df=5) (mean difference in peak concentration of 28.5 pg/ml). No differences were found with a change in posture from a sitting to a standing position. The hemoconcentration and hemodilution associated with posture changes may play a role in altering plasma protein bound hormones such as melatonin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1998.tb00536.x
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  • 2
    Electronic Resource
    Electronic Resource
    Nocturnal plasma melatonin concentrations in healthy volunteers: Effect of single doses of d-fenfluramine, paroxetine, and ipsapirone (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 21 (1996), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effect on nocturnal melatonin secretion of acute administration of the indirectly acting serotonin (5-HT) receptor agonists d-fenfluramine (30 mg) and paroxetine (20 mg) and a partial 5-HT1A receptor agonist ipsapirone (20 mg) was investigated in healthy male volunteers and compared to a placebo condition. Each subject (n=8) received each drug on one occasion over a 4 week study period, with drug administration separated by 1 week. A randomized, counter-balanced design was used. Drugs or placebo were administered at 2,000 hours in the light, and all blood samples were collected throughout the night in the dark at regular intervals until 0600 hours. Neither d-fenfluramine, paroxetine, or ipsapirone following acute dosage had a statistically significant effect on nocturnal melatonin synthesis. The lack of effect seen with d-fenfluramine, paroxetine, and ipsapirone may be due to limitations imposed by the dose requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1996.tb00271.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of atenolol, a p!-adrenergic antagonist, on nocturnal plasma melatonin secretion: Evidence for a dose-response relationship in humans (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 23 (1997), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Nathan PJ, Maguire KP, Burrows GD, Norman T.R. The effect of atenolol, a β1-adrenergic antagonist, on nocturnal plasma melatonin secretion: Evidence for a dose-response relationship in humans. J. Pineal Res. 1997; 23:131–135. © Munksgaard, Copenhagen〈section xml:id="abs1-1"〉〈title type="main"〉AbstractPineal β1-adrenergic receptors are involved in the regulation of melatonin secretion. The involvement of β1adrenergic receptors has been demonstrated by the ability of acute administration ofβ-antagonists to suppress the nocturnal rise of circulating melatonin and its urinary metabolite 6-sulphatoxymelatonin (aMT6s). The present study was undertaken to examine the relationship between increasing doses of atenolol and nocturnal plasma melatonin concentrations. Six healthy subjects participated in the study for a period of 5 weeks. Subjects were administered placebo, 12.5, 25, 37.5, and 50 mg doses of atenolol in a randomized single blind design. Each dose was separated by a 1 week washout period. Blood samples were collected at regular intervals from 19.00 hr to 06.00 hr. Repeated measures analysis of variance showed a dose-dependent decrease in plasma melatonin concentrations (P 〈 0.01). A Student Newman-Keuls post hoc test indicated significant differences between placebo and all doses of atenolol (P 〈 0.05). The results demonstrate a dose-dependent relationship between β1-receptor blockade and suppression of nocturnal plasma melatonin in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1997.tb00345.x
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    Paper (German National Licenses)
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