Spectral properties of the TGF pathway

The tubuloglomerular feedback (TGF) mechanism regulates the rate of fluid and solute entry into the nephrons, the functional units of the kidney. Experiments in rats have shown that key variables in the TGF pathway may exhibit a regular, sustained oscillation, of frequency ∼35 mHz; further experiments have revealed substantial spectral complexity, of unknown etiology, up to 500 mHz, in blood flow through the associated vasculature. We have previously published a simple mathematical model of the TGF pathway that predicts the low-frequency oscillation. Here we report additional analysis of the model that suggests that the spectral complexity in the 50-500 mHz range arises, at least in part, from intrinsic properties of the TGF pathway.