Key Points
- To determine whether reflex excitation and inhibition alter the peak height or peak frequency components of synchronized renal sympathetic nerve activity.
- Stimulated peripheral thermal receptors via hot water tail immersion in anesthetized rats (n = 8).
- Stimulated cardiac baroreceptors via acute volume loading in conscious rats (n = 8).
- Measured synchronized renal sympathetic nerve activity peak height, peak frequency, and heart rate during both reflex interventions.
- Thermal stimulation significantly increased heart rate and peak height, whereas cardiac baroreceptor stimulation significantly decreased heart rate and peak height.
- Peak frequency of synchronized renal sympathetic nerve activity remained unchanged during both sympathoexcitatory and sympathoinhibitory reflexes.
- Reflex shifts in nerve activity were mediated by changing the number of active renal nerve fibers, including the recruitment of previously silent fibers during thermal stimulation, rather than altering central rhythm.
Structured PICO
PPopulationRats (n=8 anesthetized, n=8 conscious)
IInterventionPeripheral thermal receptor stimulation (tail in hot water) and cardiac baroreceptor stimulation (volume loading)
OOutcomePeak height and peak frequency of synchronized renal sympathetic nerve activity (RSNA)surrogate
Reflex changes in renal sympathetic nerve activity are driven by recruitment or inhibition of active nerve fibers rather than changes in central rhythm frequency.