Abstract
The distribution and metabolism of ACTH and the dynamics of the adrenal cortical response to this tropic hormone were characterized in the rat, through mathematical models involving data derived from experiments, where plasma corticosterone concentrations were measured following both single injections and infusions of ACTH. The models, which incorporate a previously established model of the dynamics of plasma corticosterone, were statistically validated. The simulated dynamics of the different processes linking ACTH secretion by the adenohypophysis to corticosterone secretion by the adrenal cortex include: (1) a variable MCR for plasma ACTH, modeled as the sum of a constant and a saturable degradation process; (2) the ability of the adrenal gland to secrete at a maximal rate aven after the plasma ACTH concentration has become negligible, modeled as the accumulation of an intermediary productZ directly controlled by the plasma ACTH concentration; (3) a saturable secretion with a small time constant and which, for single injections, always starts in the same fashion, modeled as a “synthesis process” whose input is a saturable function ofZ; (4) an immediate fall of the plasma corticosterone concentration at the end of the ACTH infusions, modeled as a “release process” also controlled byZ.
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Supported by grants from the Medical Research Council of Canada (MT-1205, MT-1555, and MA-4970), and from INSERM, France (CRL-76-5-020-4).
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Perrin, F., Normand, M. & Fortier, C. Analysis through mathematical models of the dynamics of the adrenal cortical response to ACTH in the rat. Ann Biomed Eng 6, 1–15 (1978). https://doi.org/10.1007/BF02584528
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DOI: https://doi.org/10.1007/BF02584528