Long-term control of renal blood flow: what is the role of the renal nerves?

2001 ◽  
Vol 280 (5) ◽  
pp. R1534-R1545 ◽  
Author(s):  
Carolyn J. Barrett ◽  
Michael A. Navakatikyan ◽  
Simon C. Malpas
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Renal Nerves ◽  
Renal Vasculature ◽  
Nerve Activity ◽  
Renal Sympathetic

We have developed a system for long-term continuous monitoring of cardiovascular parameters in rabbits living in their home cage to assess what role renal sympathetic nerve activity (RSNA) has in regulating renal blood flow (RBF) in daily life. Blood pressure, heart rate, locomotor activity, RSNA, and RBF were recorded continuously for 4 wk. Beginning 4–5 days after surgery a circadian rhythm, dependent on feeding time, was observed. When averaged over all days RBF to the innervated and denervated kidneys was not significantly different. However, control of RBF around these mean levels was dependent on the presence of the renal sympathetic nerves. In particular we observed episodic elevations in heart rate and other parameters associated with activity. In the denervated kidney, during these episodic elevations, the increase in renal resistance was closely related to the increase in arterial pressure. In the innervated kidney the renal resistance response was significantly more variable, indicating an interaction of the sympathetic nervous system. These results indicate that whereas overall levels of RSNA do not set the mean level of RBF the renal vasculature is sensitive to episodic increases in sympathetic nerve activity.

Effect of renal denervation on dynamic autoregulation of renal blood flow

2004 ◽  
Vol 286 (6) ◽  
pp. F1209-F1218 ◽  
Author(s):  
Gerald F. DiBona ◽  
Linda L. Sawin
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Sympathetic Nerve ◽  
Renal Denervation ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Spontaneously Hypertensive ◽  
Renal Sympathetic Nerve ◽  
Renal Sympathetic

Vasoconstrictor intensities of renal sympathetic nerve stimulation elevate the renal arterial pressure threshold for steady-state stepwise autoregulation of renal blood flow. This study examined the tonic effect of basal renal sympathetic nerve activity on dynamic autoregulation of renal blood flow in rats with normal (Sprague-Dawley and Wistar-Kyoto) and increased levels of renal sympathetic nerve activity (congestive heart failure and spontaneously hypertensive rats). Steady-state values of arterial pressure and renal blood flow before and after acute renal denervation were subjected to transfer function analysis. Renal denervation increased basal renal blood flow in congestive heart failure (+35 ± 3%) and spontaneously hypertensive rats (+21 ± 3%) but not in Sprague-Dawley and Wistar-Kyoto rats. Renal denervation significantly decreased transfer function gain (i.e., improved autoregulation of renal blood flow) and increased coherence only in spontaneously hypertensive rats. Thus vasoconstrictor intensities of renal sympathetic nerve activity impaired the dynamic autoregulatory adjustments of the renal vasculature to oscillations in arterial pressure. Renal denervation increased renal blood flow variability in spontaneously hypertensive rats and congestive heart failure rats. The contribution of vasoconstrictor intensities of basal renal sympathetic nerve activity to limiting renal blood flow variability may be important in the stabilization of glomerular filtration rate.

Relationship between renal sympathetic nerve activity and renal blood flow during natural behavior in rats

2004 ◽  
Vol 286 (5) ◽  
pp. R881-R887 ◽  
Author(s):  
Misa Yoshimoto ◽  
Tamaki Sakagami ◽  
Satsuki Nagura ◽  
Kenju Miki
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Rem Sleep ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nrem Sleep ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Behavioral Activities ◽  
Renal Sympathetic

The purpose of the present study was to determine the relationship between renal sympathetic nerve activity (RSNA) and renal blood flow (RBF) during normal daily activity in conscious, chronically instrumented Wistar rats ( n = 8). The animal's behavior was classified as rapid eye movement (REM) sleep, non-REM (NREM) sleep, quiet awake, moving, and grooming states. On average RSNA was lowest during REM sleep, which was decreased by 39.0 ± 3.2% ( P < 0.05) relative to NREM sleep, and rose linearly with an increase in activity level in the order of quiet awake (by 10.9 ± 1.8%, P < 0.05), moving (by 29.4 ± 2.9%, P < 0.05), and grooming (by 65.3 ± 3.9%, P < 0.05) relative to NREM sleep. By contrast, RBF was highest during REM sleep, which was increased by 4.8 ± 0.7% ( P < 0.05) relative to NREM sleep and decreased significantly ( P < 0.05) by 5.5 ± 0.6 and 6.6 ± 0.5% during moving and grooming states, respectively, relative to NREM sleep. There was a significant ( P < 0.05) inverse linear relationship between the percent changes in RSNA and RBF and between those in RSNA and renal vascular conductance. Furthermore, renal denervation ( n = 8) abolished the changes in RBF induced by different natural behavioral activities. These results suggest that the changes in RSNA induced by natural behavioral activities had a significant influence on RBF.

Cardiovascular and neurohormonal effects of intravenous adrenomedullin in conscious rabbits

1995 ◽  
Vol 269 (5) ◽  
pp. R1289-R1293 ◽  
Author(s):  
M. Fukuhara ◽  
T. Tsuchihashi ◽  
I. Abe ◽  
M. Fujishima
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic Nerve ◽  
Conscious Rabbits ◽  
Renal Sympathetic

Adrenomedullin is a vasodilative peptide and shows slight homology with calcitonin gene-related peptide. In the present study, we investigated the effects of adrenomedullin on cardiovascular and neurohormonal responses in 13 conscious rabbits. The animals were chronically instrumented with bipolar electrodes on the left renal sympathetic nerve. Intravenous administration of human adrenomedullin (10, 100, 1,000, and 3,000 pmol/kg, n = 6) caused a dose-dependent reduction in mean arterial pressure (0 +/- 2, -1 +/- 2, -19 +/- 2, and -29 +/- 4 mmHg, respectively) concomitant with increases in heart rate, renal sympathetic nerve activity, plasma renin activity, and plasma norepinephrine. The significant reduction in mean arterial pressure induced by 1,000 pmol/kg of adrenomedullin occurred within 1 min after injection and lasted for 15 min (n = 7). In contrast, the significant increases in heart rate and renal sympathetic nerve activity lasted for more than 50 min. When mean arterial pressure was decreased by 15 mmHg by adrenomedullin, the increases in heart rate and renal sympathetic nerve activity were 53 +/- 8 beats/min and 78 +/- 13%, respectively, which were significantly smaller than those induced by intravenous injection of sodium nitroprusside (102 +/- 14 beats/min and 155 +/- 34%, respectively). These results suggest that intravenous adrenomedullin exerts a hypotensive action that is associated with the attenuated reflex-mediated sympathetic activation.

Discharge Pattern of Renal Sympathetic Nerve Activity in the Conscious Rat: Spectral Analysis of Integrated Activity

2000 ◽  
Vol 84 (6) ◽  
pp. 2859-2867 ◽  
Author(s):  
Takato Kunitake ◽  
Hiroshi Kannan
Keyword(s):  
Heart Rate ◽  
Power Spectrum ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Low Frequency ◽  
Heart Beat ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Conscious Rats ◽  
Renal Sympathetic

We investigated the periodic characteristics of bursting discharge in renal sympathetic nerve activity (RSNA) in conscious rats. Employing a discrete fast Fourier transform algorithm, a power spectrum analysis was used to quantify periodicities present in rectified and integrated RSNA whose signal-to-noise ratio in the recordings was greater than six. In conscious rats with intact baroreceptors, RSNA was characterized by four frequency components occurring at about 0.5, 1.5, 6, and 12 Hz, which corresponded to the low-frequency fluctuation of heart rate, respiration, and frequency of heart beat, and its harmonics, respectively. After intravenous infusion of sodium nitroprusside (SNP) to elicit reflex increases in RSNA and heart rate, the power for the component at 6 Hz followed the changes in heart beat frequency and was significantly increased, while those for the three other components were attenuated or experienced no change. In sino-aortic denervated (SAD) conscious rats, all four components were abolished, and the power spectrum was well fitted by a flat or Lorentzian curve, suggesting an almost random pattern. Only a respiratory-related component, which suggested common central modulation, appeared sporadically for short periods but was absent for the most part. Therefore most of this component together with the low-frequency component was also likely due to the baroreceptor-dependent peripheral modulation. The activity was sorted in 15 subgroups on the basis of spike amplitudes in the RSNA. Each subgroup showed frequency characteristics similar to the whole nerve activity. These results suggest that all periodicity in the RSNA of conscious rats with intact baroreceptors is caused by the baroreceptor input.

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