Key result
Renal nerve stimulation in CHF rats resulted in a 10-fold increase in renal blood flow power and a flat gain response (-20 dB) over the 0.1 to 1.0 Hz frequency range compared to control rats.
The enhanced renal vasoconstrictor response to renal nerve stimulation in CHF rats is due to an impaired low-pass filter function of the renal vasculature.
No immediate clinical implications for HF management; leaves open whether renal vascular filter defects drive sympathetic overdrive in humans.
BACKGROUND: The renal vasoconstrictor response to renal nerve stimulation is greater in congestive heart failure (CHF) rats than in control rats. This study tested the hypothesis that the enhanced renal vasoconstrictor response to renal nerve stimulation in CHF is a result of an impairment in the low-pass filter function of the renal vasculature. METHODS AND RESULTS: In response to conventional graded-frequency renal nerve stimulation, the reductions in renal blood flow at each stimulation frequency were greater in CHF rats than control rats. A pseudorandom binary sequence pattern of renal nerve stimulation was used to examine the frequency response of the renal vasculature. Although this did not affect the renal blood flow power spectrum in control rats, there was a 10-fold increase in renal blood flow power over the frequency range of 0.01 to 1.0 Hz in CHF rats. On analysis of transfer function gain, attenuation of the renal nerve stimulation input signal was similar in control and CHF rats over the frequency range of 0.001 to 0.1 Hz. However, over the frequency range of 0.1 to 1.0 Hz, although there was progressive attenuation of the input signal (-30 to -70 dB) in control rats, CHF rats exhibited a flat gain response (-20 dB) without progressive attenuation. CONCLUSIONS: The enhanced renal vasoconstrictor response to renal nerve stimulation in CHF rats is caused by an alteration in the low-pass filter function of the renal vasculature, resulting in a greater transfer of input signals into renal blood flow in the 0.1 to 1.0 Hz range.
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DiBona et al. (2003) studied Congestive heart failure (animal model). Renal nerve stimulation vs. Control rats was evaluated on Renal blood flow power spectrum and transfer function gain. Renal nerve stimulation in CHF rats resulted in a 10-fold increase in renal blood flow power and a flat gain response (-20 dB) over the 0.1 to 1.0 Hz frequency range compared to control rats.
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