Afferent baroreceptor model fits. The afferent baroreceptor model, given by –, is used to fit step (*A*) and ramp (*C*) datasets associated with the WKY rat strain. *A*: dynamic components of the model are parameterized using baroreceptor step-response data (○) collected in experiments of Brown et al. (). Pressure steps of 130 (*bottom* trace), 150, 170, 190, 210, and 230 (*top* trace) mmHg were applied to an isolated aortic arch preparation. The linearized version of the dynamic model () was used to produce the fits (solid lines) shown. The optimal values of the dynamic parameters estimated from these fits are *K*_{ne} = 1, *K*_{1} = 1.5, *K*_{2} = 3.75, *K*_{3} = 1.05, *B*_{1} = 1, *B*_{2} = 10, *B*_{3} = 300, *B*_{wall} = 1 (note: units of *K*s are mmHg/mm and units of *B*s are mmHg·s/mm). The values of static parameters used to produce these fits are *S* = 255 Hz, δ_{th} = 0.2, and ζ = 1. *B*: model fits to *A* are illustrated in a time-scale consistent with the rapid-resetting phase of the response. There were not sufficient data in the 12 second step-response data of Brown et al. to identify the model components associated with the rapid-resetting phase. Therefore, the parameter *B*_{3} in our model was not identified here. *C*: model fits to 2 mmHg/s pressure ramp-response data (open markers) of a population of 3 baroreceptor fibers collected in experiments of Andresen () are shown. Both the nonlinear (solid line) and linearized (dashed line) models were used to fit the data associated with the circle markers. The values of static parameters used to produce the nonlinear fit are *S* = 800 Hz, δ_{th} = 0.18, and ζ = 0.93. The values used to produce the linear fit are *S* = 500 Hz, δ_{th} = 0.21, and ζ = 0.9. The values of dynamic parameters used in the fits of *C* are the same as those used to produce the fits of *A*. The values of the static parameters used to produce the fits of *C* were not used in later analyses. Instead, values of these static parameters were selected to match data of the SS strain (from Ref. , not shown) and are given in .

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