Tubuloglomerular-feedback Mediated Dynamics in Two Coupled Nephrons

Friday, February 12, 1999 - 2:30pm - 3:00pm
Keller 3-180
E. Bruce Pitman (University at Albany (SUNY))
This talk describes tubuloglomerular feedback (TGF) regulated fluid flow in coupled nephrons. In previous work, a minimal model of a single nephron was developed. Analysis of the model equations suggests that a Hopf bifurcation can occur along a locus in parameter space, a finding that may explain experimentally observed regular oscillations in nephron fluid flow. Here, the single-nephron model is extended to two nephrons, with coupled glomerular filtration rates. Analysis of the model equations for coupled nephron flow indicates that sustained oscillations in nephron fluid flow and chloride concentration may emerge as a result of a Hopf bifurcation. However, these sustained oscillations emerge at a lower value of feedback gain, relative to a single (i.e., uncoupled) nephron. Depending on parameter values, numerical solutions of the model equations may exhibit synchronous oscillations, entrainment, beats, or more complex dynamics.