Abstract
Our aim is the development of noninvasive methods for assessing the nutritional and metabolic statue. For this purpose we developed HPLC methods to selectively measure the turnover of rRNA (from urinary pseudouridine, ψ). tRNA (from N2, N2-dimethylguanosine, m22G) and mRNA (from 7-methylguanine, m7Gua). Preliminary data from preterm infants suggested that any kind of general stress (hunger, infection, artificial ventilation) increases excretion rates of ψ, m22G, m7Gua as well as that of 3-methylhistidine (m3His; from actin and myosin breakdown). We therefore studied the excretion of ψ, m7Gua and m3His in growing rats (age 41-46 days) fed either a control diet ad libitum or 1/2 and 1/4 respectively of the amounts consumed by the control animals. In control animals N retention was ∼ 1.4 g/kg/d throughout the 5-day period studied. With half the food intake of the controls, N retention briefly fell to zero but returned to near-normal values (∼1 g/kg/d) thereafter. Animals given 1/4 of the normal food intake had a negative N retention throughout. ψ and m7Gua excretion increased within a day in these animals (by 45 and 24 %, respectively) and fell to values at or below normal after ∼ 3 days, whereas m3His excretion increased by 50 % on the second day and remained on this level. We conclude that there was a rapid transient breakdown of ribosomes and mRNA followed by a longer lasting breakdown of actin + myosin in food restriction. Measurement of modified RNA catabolites in urine may therefore represent a means to assess rapid changes in metabolic state, while m3His excretion and N balance may be more appropriate for monitoring longer lasting deficiencies.
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Schöch, G., Held, A., Topp, H. et al. 88 INFLUENCE OF FOOD RESTRICTION ON URINARY EXCRETION OF MODIFIED RNA CATABOLITES AND OF 3-METHYLHISTIDINE IN RELATION TO NITROGEN BALANCE IN GROWING RATS. Pediatr Res 24, 419 (1988). https://doi.org/10.1203/00006450-198809000-00111
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DOI: https://doi.org/10.1203/00006450-198809000-00111