Modulation of the Myogenic Mechanism:Concordant effects of NO Synthesis Inhibition and O2- Dismutation on Renal Autoregulation in the Time and Frequency Domains.

Modulation of the Myogenic Mechanism:Concordant effects of NO Synthesis Inhibition and O2- Dismutation on Renal Autoregulation in the Time and Frequency Domains. Am J Physiol Renal Physiol. 2016 Jan 28;:ajprenal.00461.2015 Authors: Moss NG, Kopple TE, Arendshorst WJ Abstract Renal blood flow (RBF) autoregulation was investigated in anesthetized C57Bl6 mice using time- and frequency-domain analyses. Autoregulation was reestablished by 15 sec in two stages after a 25 mmHg step increase in perfusion pressure (RPP). The renal vascular resistance (RVR) response did not include a contribution from the macula densa tubuloglomerular feedback mechanism (MD-TGF). Inhibition of nitric oxide synthase (NOS) (L-NAME) reduced the time for complete autoregulation to 2 sec and induced 0.25 Hz oscillations in RVR. Quenching of superoxide (O2-) (SOD mimetic tempol) during L-NAME normalized the speed and strength of stage 1 of the RVR increase and abolished oscillations. The slope of stage 2 was unaffected by L-NAME or tempol. These effects of L-NAME and tempol were evaluated in the frequency domain during random fluctuations in RPP. NOS inhibition amplified the resonance peak in admittance gain at 0.25 Hz and markedly increased the gain slope at the upper myogenic frequency range (0.06 to 0.25 Hz, identified as stage 1), with reversal by tempol. The slope of admittance gain in the lower half of the myogenic frequency range (equated with stage 2) was no...
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research