Acute effect of phosphorus on postprandial partitioning of energy -

Abstract

Lately, modernization and changes in dietary habits including the decreased phosphorus intake are increasing obesity rates. It is known that phosphorus provides ATP with its phosphate, making it vital for energy production, thus, the importance of its employment in carbohydrates metabolism for energy production. Previous studies have shown that hypophosphatemia reduces ATP production and in turn leads to a reduction in protein and glycogen synthesis and impaired fat oxidation. However, the acute effect of phosphorus manipulation of meal on in vivo postprandial glycogen has never been studied. The aim of this study is to investigate the acute effect of phosphorus on glycogen synthesis after the ingestion of a meal. After receiving the approval of the Institutional Animal Care and Use Committee (IACUC) at the American University of Beirut, forty five male Sprague-Dawley rats, of around 200 g, were randomly divided into five groups and kept under monitoring for 2 weeks: control group (water), two groups sacrificed after 2 hours from food ingestion (with and without phosphorus) [(2-p) and (2+P)] and two groups sacrificed after 4 hours from food ingestion (with and without phosphorus) [(4-p) and (4+P)]. In vivo glycogen synthesis was measured using labeled 13C1 glucose, by determining its distribution on the different carbons of the glucose molecules. Total glycogen production changed according to time and on phosphorus intake, with the maximal production being in the group (4+P), and the most preferred route for glycogen synthesis was the direct pathway. However, these observations were influenced by other factors, mainly hormonal factors, including insulin, ghrelin and GLP-1. In conclusion, phosphorus did show an influence on the amount of glycogen synthesized in the different experimental groups, as well as in the pathway preferred for the production, leaving us the possibility to further investigate the results and expand it to other fuels, such as protein and fat.