Sympathoexcitatory responses to renal chemosensitive stimuli are exaggerated at nighttime in rats

Abstract

The current study discovers that the circadian cycle influences sympathetic and hemodynamic responses to activation of renal chemosensitive sensory fibers. Sympathetic responses to intrarenal bradykinin or capsaicin infusion were exaggerated during nighttime (active period), but mechanosensitive responses to elevated renal pelvic pressure were not. Importantly, renal afferent nerve responses were not different between nighttime and daytime. These data suggest that the circadian cycle modulates sympathetic responses to visceral afferent activation.