Introduction: The majority of collagen is found in connective tissues of the skeletal system. In diseases like Osteogenesis Imperfecta, the collagen synthesis is disturbed. The interest of this study is to determine if supplementation of amino acids can influence the Fractional Synthese Rate (FSR) of collagen I, especially in growing bone. We developed a method for direct measurement of collagen I s ynthesis in long bones.

Methods: Thirteen piglets were randomly divided into two groups. The animals were fed a standard diet. Group 1, was supplemented amino acids, counting for 150% of the normal protein intake, intravenously by constant infusion, starting 3 days prior to the experiment. Group 2 served as a control group. L-[1-13C]-valine was used as a tracer, and isotopic enrichment in plasma a-ketoisovalerate (KIV) was used as an indicator for intracellular valine enrichment. The tracer infusion rate was adapted to maintain a constant tracer to tracee ratio of the labeled amino acid precursor in the plasma blood samples were taken to measure the isotopic enrichment, P1CP, IGF1 and the amount of amino acids. At the end of the experiment the animals were killed and the femora were taken and new formed bone was collected just below the growth plate and collagen I was isolated, hydrolyzed, enrichment in valine with combustion mass spectrometry and FSR was calculated from the incorporation of the labeled valine in long bones.

Results: Although the amount of amino acids in blood in group I was much higher, there was no significant difference between the FSR of the amino acid group I (44.1% /day, SD 6.7) and the control group II (48.2%/day, SD 9.2). There was also no significant difference between the amount of P1CP and IGF between the groups.

Conclusion: Supplementation of a normal diet with amino acids doesn’t stimulate the collagen I synthesis in new formed bone.