Responses in the absorptive phase in muscle and liver protein synthesis rates of growing rats

S Dänicke, R Nieto, Gerald Lobley, M F Fuller, David Stanley Brown, Eric Milne, Alexander Graham Calder, S Chen, I Grant, W Böttcher

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7 Citations (Scopus)


The effect of time after beginning of a meal (30, 60, 90 and 120 min) on liver and gastrocnemius muscle protein synthesis was tested in growing male rats using the large dose technique, based on a 10 min exposure to [15N]phenylalanine. The fractional synthesis rate was estimated from the ratio between the atom percent excess of tissue protein-bound and free labelled phenylalanine. The latter was measured by gas chromatography mass spectrometry using the tertiary-butyldimethylsilyl amino acid derivatives. The protein-bound phenylalanine of gastrocnemius muscle was separated from the other amino acids using preparative amino acid chromatography and then oxidised to N2 in an automated carbon-nitrogen Roboprep (CN) combustion module attached to a continuous flow isotope ratio mass spectrometer (IRMS), with m/z ions 28 and 29 monitored. The protein-bound phenylalanine from liver was separated by a gas chromatograph attached to a sample preparation module and an isotope ratio mass spectrometer (GC C-IRMS), with again m/z ions of 28 and 29 monitored. The following results were obtained: the daily fractional protein synthesis rates (ks) in gastrocnemius muscle and liver were 13.9% and 65.6% respectively, in 12 h fasted 145 g rats. These ks increased within 30 min after ingestion of meal to 14.9% and 91.8% for muscle and liver, respectively, and remained at these values for the next 90 min (14.6% and 87.4% at 60 min, and 14.3% and 88.6% at 120 min after the beginning of feeding). It was concluded that measurement of protein synthesis rates characteristics for the absorptive phase can be undertaken in a period from thirty minutes to two hours after start of a meal, without significant changes in the ks values.
Original languageEnglish
Pages (from-to)41-52
Number of pages12
JournalArchiv für Tierernährung
Issue number1
Publication statusPublished - 1 Jan 1999


  • Amino Acids
  • Animals
  • Eating
  • Intestinal Absorption
  • Liver
  • Male
  • Mass Spectrometry
  • Muscle Proteins
  • Muscle, Skeletal
  • Nitrogen Isotopes
  • Phenylalanine
  • Protein Biosynthesis
  • Rats
  • Time Factors


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