Characterization of Dynamics in Renal Autoregulation Using Volterra Models

The dynamics of renal autoregulation are modeled using a modified Volterra representation called the fixed pole expansion technique (FPET). A data dependent procedure is proposed for selecting the pole locations in this expansion that enables a reduction in model complexity compared to standard Volterra models. Furthermore, a quantitative characterization of frequency dependent features of the renal autoregulatory response is enabled via the model's pole locations. The utility of this approach is demonstrated by applying the modeling technique to renal blood pressure and renal blood flow measurements in conscious rats. The model is used to characterize the myogenic autoregulatory response in control rats and rats whose renal autoregulation has been impaired by calcium channel blockers.