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Evidence for Multi‐Stability of the Tubuloglomerular Feedback System in Spontaneously‐Hypertensive Rats (SHR)
Author(s) -
Moore Leon C,
Siu Kin L,
Layton Anita T,
Layton Harold E,
Chon Ki H
Publication year - 2006
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.20.4.a762
Subject(s) - tubuloglomerular feedback , transforming growth factor , chemistry , medicine , endocrinology , kidney
A recent modeling study (Layton, et al., AJP Renal, in press) predicted that the tubuloglomerular feedback (TGF) system in SHR may exhibit multi‐stability, (viz., steady‐flows or stable primary‐ or secondary‐mode TGF oscillations). TGF multi‐stability is predicted when TGF gain is high, which has been reported in several publications, and if TGF system tubular delays are elongated relative to normotensive rats. In a micropuncture study, we found Henle’s loop transit time in SHR (n=12) to be ~70% longer than in Sprague‐Dawley rats (n=9) (SDR). This implies a ~26% lower TGF oscillatory frequency in SHR relative to SDR. Further, TGF multi‐stability in coupled nephrons is predicted to produce simultaneous peaks within the TGF frequency band, as well as abrupt and gradual shifts in TGF oscillatory frequency. These features and low primary TGF frequencies are seen in SHR time‐varying power spectra of cortical blood flow (CBF) measured via laser Doppler under anesthesia, in RBF in conscious rats, and in published spectra. Together, these results lend support to the concept that the TGF system may exhibit multi‐stability, a property that, in coupled nephrons, can result in complex TGF fluctuations similar to those observed in SHR. Funded by NIH grants HL69629 and DK42091.