HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 295/3/F734    most recent 00115.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Iliescu, R. Articles by Ryan, M. J. Search for Related Content PubMed PubMed Citation Articles by Iliescu, R. Articles by Ryan, M. J.

Renal blood flow and dynamic autoregulation in conscious mice

¹Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi; and ²Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia

Submitted 4 March 2008 ; accepted in final form 24 June 2008

Autoregulation of renal blood flow (RBF) occurs via myogenic and tubuloglomerular feedback (TGF) mechanisms that are engaged by pressure changes within preglomerular arteries and by tubular flow and content, respectively. Our understanding of autoregulatory function in the kidney largely stems from experiments in anesthetized animals where renal perfusion pressure is precisely controlled. However, normally occurring variations in blood pressure are sufficient to engage both myogenic and TGF mechanisms, making the assessment of autoregulatory function in conscious animals of significant value. To our knowledge, no studies have evaluated the dynamics of RBF in conscious mice. Therefore, we used spectral analysis of blood pressure and RBF and identified dynamic operational characteristics of the myogenic and TGF mechanisms in conscious, freely moving mice instrumented with ultrasound flow probes and arterial catheters. The myogenic response generates a distinct resonance peak in transfer gain at 0.31 ± 0.01 Hz. Myogenic-dependent attenuation of RBF oscillations, indicative of active autoregulation, is apparent as a trough in gain below 0.3 Hz (–6.5 ± 1.3 dB) and a strong positive phase peak (93 ± 9 deg), which are abolished by amlodipine infusion. Operation of TGF produces a local maximum in gain at 0.05 ± 0.01 Hz and a positive phase peak (62.3 ± 12.3 deg), both of which are eliminated by infusion of furosemide. Administration of amlodipine eliminated both myogenic and TGF signature peaks, whereas furosemide shifted the myogenic phase peak to a slower operational frequency. These data indicate that myogenic and TGF dynamics may be used to investigate the effectiveness of renal autoregulatory mechanisms in conscious mice.

myogenic; tubuloglomerular feedback; mouse; renal blood flow; dynamics; conscious