This article presents a very brief and concise overview of a research program that incorporates experimental and modeling techniques to advance and integrate our understanding of animal metabolism. After introductory remarks directed at setting context and a couple definitions, focus is directed to models of tissue metabolism using ruminant adipose tissue as an example to illustrate the interplay of modeling and experimental research. Equations depicting the interesting interactions among glucose, acetate, and insulin in effecting rates of lipogenesis from acetate, glucose uptake, and pentose cycle flux are presented along with a very brief description of the data required and the reasoning underlying the equation forms adopted. The key observations are that acetate incorporation into fatty acids is highly dependent on the availability (concentration) of glucose and vice versa, and that rates of utilization of both nutrients are enhanced by insulin. The well-known effect of insulin on glucose uptake is not adequate for accurate simulations of observed responses in this ruminant adipose tissue. Thus, provision for the insulin-induced covalent modification of acetyl-CoA carboxylase to a more active form reported for adipose tissue in other species but not yet for ruminants is incorporated to enable the accurate simulations of reality that are the goal and test of research models. The key link between lipogenesis from acetate and increased glucose oxidation is clearly due to increased NADP availability drawing G6P into the pentose cycle as represented in the model.
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