Abstract
Water homeostasis is one of the body's most critical tasks. Physical challenges to the body, including exercise and surgery, almost always coordinate with some change in water handling reflecting the changing needs of the body. Vasopressin is the most important hormone that contributes to short‐term water homeostasis. By manipulating vascular tone and regulating water reabsorption in the collecting duct of the kidneys, vasopressin can mediate the retention or loss of fluids quickly. In this study, we validated HumMod, an integrative mathematical model of human physiology, against six different challenges to water homeostasis with special attention to the secretion of vasopressin and maintenance of electrolyte balance. The studies chosen were performed in normal men and women, and represent a broad spectrum of perturbations. HumMod successfully replicated the experimental results, remaining within 1 standard deviation of the experimental means in 138 of 161 measurements. Only three measurements lay outside of the second standard deviation. Observations were made on serum osmolarity, serum vasopressin concentration, serum sodium concentration, urine osmolarity, serum protein concentration, hematocrit, and cumulative water intake following dehydration. This validation suggests that HumMod can be used to understand water homeostasis under a variety of conditions.
Highlights
Water homeostasis is an important physiological task to study: hospital readmissions due to dehydration are critical sources of cost following bariatric surgery, ileostomy, and pancreaticoduodenectomy (Whipple), as well as in end-of-life care
Even in the acute setting, is managed by multiple control systems that interact with one another, but these efforts are led by AVP
We summarize the systems controlling short-term water homeostasis in the model and attempt to validate it in the setting of dehydration and the transient response to rehydration
Summary
Water homeostasis is an important physiological task to study: hospital readmissions due to dehydration are critical sources of cost following bariatric surgery, ileostomy, and pancreaticoduodenectomy (Whipple), as well as in end-of-life care. Even in the acute setting, is managed by multiple control systems that interact with one another, but these efforts are led by AVP (vasopressin or antidiuretic hormone, ADH). Water homeostasis involves multiple systems at different times. We summarize the systems controlling short-term water homeostasis in the model and attempt to validate it in the setting of dehydration and the transient response to rehydration. We demonstrate the capacity of our model to simulate dehydration/rehydration experiments previously published in human populations and to validate the model for further investigations into water homeostasis in man. No integrative model of serum osmolarity and AVP exists
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