The purpose of this proposal is to develop a validated physiological model of the cardio- renal axis for submission to the FDA Medical Device Development Tool pilot program. The model will be used to aid in the development and regulation of devices intended to treat hypertension. Examples include medical devices for renal nerve ablation, electrical stimulation of the carotid baroreceptor or creation of an A-V Fistula. Given that 12-15% of US patients with uncontrolled hypertension even with the use of 4 or more drugs at a price tag of $11-$17 billion, the importance of a tool that streamlines the time for design, testing, and regulation of a non- pharmacological device is clear. The multifactorial nature of hypertension complicates its treatment, and no device intervention is guaranteed to successfully treat each patient. Our physiological model is a powerful tool for understanding interpatient variability and confirming the correctness of a device's context of use. In Phase I, we will demonstrate a validated and documented renal model, using HumMod, our existing model of human physiology as the basis for the new model. The aims of this study include: 1) the transfer of the model from a proprietary simulation environment into a more powerful, validated framework, 2) documentation of the model by linking a bibliographic database with a wiki, and 3) a validation suite to ensure that the model functions correctly. The model will be implemented in Modelica, a multi-domain modeling language for modeling of complex system. In Phase II, we will use the workflows developed in Phase I to create, document, and validate the cardiovascular part of the axis, including neural reflex arcs and the relevant endocrine systems.