Math @ Duke

Publications [#287306] of Harold Layton
Papers Published
 Layton, HE; Pitman, EB; Moore, LC, Potential natriuretic effects of limitcycle oscillations mediated by tubuloglomerular feedback,
Faseb Journal, vol. 12 no. 4
(1998),
pp. A108, ISSN 08926638
(last updated on 2019/01/17)
Abstract: Previously, we used a mathematical model to show that limitcycle oscillations in nephron water and NaCl flow emerge when tubuloglomerular feedback (TGF) gain magnitude γ exceeds a critical value γc ≈ 3.5. Here, we used the model to investigate the effect of oscillations on the ability of TGF to regulate water and NaCl delivery to the distal nephron. For γ < γc, the TGF system, if transiently perturbed, returned to a steadystate in which distal delivery of water and NaCl was independent of γ. Moreover, feedback compensation for infinitesimal sustained perturbations agreed well with the predictions of linear systems theory (LST). However, for γ > γc, as the system tended to a limit cycle, two phenomena emerged. First, as γ increased from γc to 10, timeaveraged NaCl delivery increased 3.7% above steadystate delivery, whereas water delivery deviated from the steadystate by < 0.5%. Second, for γ > γc, feedback compensation was reduced up to 21%, in comparison with the predictions of LST. Hence, these studies suggest that the emergence of TGF oscillations increases distal NaCl delivery and limits regulatory ability, effects that tend to enhance sodium excretion.


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