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Laser‐speckle analysis of renal cortical perfusion – regional perfusion dynamics
Author(s) -
Cupples William A,
Waring Jennifer,
HolsteinRathlou NielsHenrik,
Chon Ki,
Braam Branko
Publication year - 2010
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.24.1_supplement.1059.25
Subject(s) - perfusion , chemistry , autoregulation , coupling (piping) , medicine , perfusion scanning , blood pressure , materials science , metallurgy
Tubuloglomerular feedback and a myogenic mechanism act on afferent arterioles to mediate autoregulation of renal blood flow (RBF) and their actions may extend beyond single nephrons. We tested for physiologically significant coupling among neighboring nephrons. Cortical surface perfusion was assessed by laser‐speckle perfusion imaging at 1 Hz. Time series from 5 regions of interest (ROI, ~0.5 × 0.5 mm) were extracted. RBF (Transonic 400) was systematically altered by manipulation of perfusion pressure, by captopril (−/+ ANG II), and by L‐NAME. Perfusion in the ROIs (units) was linear in RBF (slope = 1120 ± 63 units × min/mL, r2 = 0.94 ± 0.03, n=5). Power spectra of the ROI time series contain the same information as RBF spectra and spectra of all ROIs are very similar. Comparing adjacent to remotely located ROIs by spectra of difference series, by linear cross spectra, and by nonlinear cross bi‐spectra showed that coupling decreased with separation between ROIs. The cross bi‐spectral coupling index declined with separation of ROIs: adjacent = 0.269, medium = 0.170, remote = 0 during control (greater index = greater coupling). ANG II infusion increased the spread of coupling: adjacent = 0.133, medium = 0.034, remote = 0.014. Local coupling suggests that autoregulation may involve coordinate action of clusters of nephrons. Coupling may be regulated by ANG II. Funded by Heart & Stroke Fdn of BC & Yukon, & Victoria Fdn