  We present progress on a comprehensive, modular, interactive modeling
environment centered on overall regulation of blood pressure and body fluid
homeostasis. We call the project SAPHIR, for "a Systems Approach for
PHysiological Integration of Renal, cardiac, and respiratory functions". The
project uses state-of-the-art multi-scale simulation methods. The basic core
model will give succinct input-output (reduced-dimension) descriptions of all
relevant organ systems and regulatory processes, and it will be modular,
multi-resolution, and extensible, in the sense that detailed submodules of any
process(es) can be "plugged-in" to the basic model in order to explore, eg.
system-level implications of local perturbations. The goal is to keep the basic
core model compact enough to insure fast execution time (in view of eventual
use in the clinic) and yet to allow elaborate detailed modules of target
tissues or organs in order to focus on the problem area while maintaining the
system-level regulatory compensations.
