Whole-body degradation rates of transfer-, ribosomal-, and messenger ribonucleic acids and resting metabolic rate in 3-to 18-year-old humans

Whole-body degradation rates of transfer, ribosomal, and messenger RNA were determined noninvasively in 3-, 6-, 10-, 14-, and 18-y-old female and male subjects (n = 14 per age group per sex) under normal living conditions. Th e method for determining the RNA degradation rates is based on measuring th e renal excretion rates of special RNA catabolites (modified ribonucleoside s and nucleobases) by HPLC. Resting metabolic rates were calculated for the same subjects by their body weights using formulas taken from literature. We found high correlations between the degradation rates of the different R NA classes (micromoles per day per kilogram body weight) and the resting me tabolic rate (kilojoules per day per kilogram body weight): in females (n = 70), r = 0.75-0.82 and in males (n = 70), r = 0.68-0.79 (p < 0.0001). We c onclude that a causal relationship exists between the whole-body degradatio n rates of the different RNA classes and the resting metabolic rate. Theref ore, in healthy subjects noninvasive determinations of RNA degradation rate s could be very useful to assess the resting metabolic rate.