Renally excreted modified RNA catabolites [pseudouridine (ѱ), N2,N2-dimethylguanosine (m22G) and N6-threoninocarbonyladenosine (t6A)] are markers of whole-body rates of degradation of rRNA and tRNA, and are thought to be potential indicators of the resting metabolic rate. To investigate diurnal variations of these RNA catabolites, the amounts of ѱ, m22G and t6A excreted were determined by HPLC of the urine from eight healthy male adults collected over 47-h periods, which were subdivided into the morning (06.00 or 09.00 to 12.00 hours), the afternoon (12.00 to 18.00 hours), the evening (18.00 to 24.00 hours) and the night (00.00 to 06.00 or 08.00 hours), under two different nutritional regimens with 100 or 50 g of protein/day. Furthermore, rates of degradation of rRNA and tRNA were calculated using values for these RNA catabolites. For comparison, the corresponding excretion of creatinine, which originates from the energy metabolism of muscle, and of 3-methylhistidine (m3His), which is an indicator of muscle protein degradation, was determined. Differences in excretion during the collection periods were tested using the Friedmann test. The excretion of ѱ, creatinine and m3His (μmol·h-1·kg-1) altered significantly (P<0.001) during the day. Medians were: for ѱ, 0.21 (morning), 0.19 (afternoon), 0.19 (evening) and 0.18 (night); for creatinine, 8.8, 8.4, 8.0 and 7.3 respectively; for m3His, 0.13, 0.11, 0.12 and 0.10 respectively. The excretion rates of m22G and t6A (nmol·h-1·kg-1) altered, but not significantly, during the day; corresponding medians were: for m22G, 9.0, 8.4, 8.0 and 8.4 respectively; for t6A, 4.3, 4.1, 3.9 and 3.9 respectively. From these results it can be concluded that, in order to assess the average daily rates of degradation of tRNA and rRNA using modified RNA catabolites, urine collection should be carried out quantitatively over 24 h periods. Likewise, the catabolites creatinine and m3His must be determined using 24 h urine samples when average daily excretion values are required.
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Research Article|
August 01 2003
Diurnal variation in the renal excretion of modified RNA catabolites in humans
Heinrich TOPP;
*Neonatology, Children's Hospital, Ernst Moritz Arndt University, Soldmannstrasse 15, D-17487 Greifswald, Germany
†Federal Institute for Drugs and Medical Devices, Kurt-Georg-Kiesinger-Allee 3, D-53175 Bonn, Germany
Correspondence: Dr Heinrich Topp, Federal Institute for Drugs and Medical Devices (e-mail [email protected]).
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Susanne UNVERZAGT;
Susanne UNVERZAGT
‡Coordination Centre for Clinical Trials, Weinbergweg 13, D-06108 Halle, Germany
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Silvia RUDLOFF;
Silvia RUDLOFF
§Institute of Nutritional Science, Justus-Liebig-University, Wilhelmstrasse 20, D-35392 Giessen, Germany
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Gerhard SCHÖCH;
Gerhard SCHÖCH
║Research Institute for Child Nutrition, Heinstück 11, D-44225 Dortmund, Germany
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Friedrich MANZ;
Friedrich MANZ
║Research Institute for Child Nutrition, Heinstück 11, D-44225 Dortmund, Germany
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Christoph FUSCH
Christoph FUSCH
*Neonatology, Children's Hospital, Ernst Moritz Arndt University, Soldmannstrasse 15, D-17487 Greifswald, Germany
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Publisher: Portland Press Ltd
Received:
September 23 2002
Revision Received:
February 27 2003
Accepted:
April 23 2003
Accepted Manuscript online:
April 23 2003
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© 2003 The Biochemical Society
2003
Clin Sci (Lond) (2003) 105 (2): 195–202.
Article history
Received:
September 23 2002
Revision Received:
February 27 2003
Accepted:
April 23 2003
Accepted Manuscript online:
April 23 2003
Citation
Heinrich TOPP, Susanne UNVERZAGT, Silvia RUDLOFF, Gerhard SCHÖCH, Friedrich MANZ, Christoph FUSCH; Diurnal variation in the renal excretion of modified RNA catabolites in humans. Clin Sci (Lond) 1 August 2003; 105 (2): 195–202. doi: https://doi.org/10.1042/CS20020253
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