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Waveform distortion in TGF‐mediated limit‐cycle oscillations: Effects of TAL flow
Author(s) -
Layton Anita T,
Moore Leon C,
Layton Harold E
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.804.14
Subject(s) - waveform , inflow , distortion (music) , oscillation (cell signaling) , physics , limit cycle , flow (mathematics) , asymmetry , nonlinear distortion , mechanics , nonlinear system , chemistry , voltage , amplifier , biochemistry , optoelectronics , cmos , quantum mechanics
Previously, we used a mathematical model to show that nonlinearities in TGF signal transduction produces a nonsinusoidal [Cl − ] waveform at the macula densa (MD) when TAL inflow is sinusoidal. The distorted [Cl − ] waveform exhibits slope asymmetry and a broad trough relative to the peak. These characteristic features are evident in many, but not all, experimental records of TGF limit‐cycle oscillations (LCO). In the present study, we used a mathematical model of the TAL with compliant walls to examine the effect of TAL flow perturbations on waveform distortion. Step‐like changes in TAL inflow pressure were examined, as were sinusoidal oscillations in inflow input pressure at differing baseline pressures. The results show that mean TAL flow strongly influences the [Cl − ] waveform at the MD. This phenomenon is a consequence of the inverse relationship between flow and transit time, which produces asymmetry between up‐ and down‐slopes of the oscillation, and the nonlinearity of TAL transport at low flow rates, which broadens the trough of the oscillation relative to the peak. These results provide an explanation for the range of waveform distortion found in experimental recordings of TGF‐mediated LCO. The degree of distortion may provide insight into TAL function, including, e.g., fractional Na + and Cl − reabsorption in the TAL. This research was supported in part by NIH grant DK‐42091 and NSF grant DMS‐0715021.