Rates of protein synthesis can be determined from the incorporation of 2H-labeled water. For example, following a bolus injection of ²H-labeled water one can collect samples (e.g. blood, liver, muscle, etc). Total proteins are isolated and their ²H-labeling is determined. This test can be performed in 2 modes, short term vs long term. In a short term study, the tracer is administered and samples are collected within hours to determine the synthesis of proteins in plasma, liver, etc. This mode is well-suited for examining the acute response of protein synthesis to a perturbation (e.g. food intake). In a long term study, the tracer is continuously administered over several days. Samples are collected and the assays are performed. The long term design yields an integrative measure of protein synthesis, i.e. the isotope is present during the fed and the fasted state and accounts for all protein synthesis over such a transition.

Note: This test does not require catheterized mice, nor does it require that mice be shipped to the MMPC. The isotopes are non-radioactive and no special safety precautions are required, the tracers will be shipped from the MMPC to the investigator. Investigators will be instructed on how to administer the isotopes, collect samples and then ship them back to the MMPC.