Very high frequency components of renal sympathetic nerve activity in conscious rats

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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Role of nitric oxide in regulation of renal sympathetic nerve activity during hemorrhage in conscious rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1999.277.1.h8 ◽

1999 ◽

Vol 277 (1) ◽

pp. H8-H14 ◽

Cited By ~ 8

Author(s):

Yoshihide Fujisawa ◽

Naoko Mori ◽

Kouichi Yube ◽

Hiroshi Miyanaka ◽

Akira Miyatake ◽

...

Keyword(s):

Nitric Oxide ◽

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

Saline Group ◽

Baroreceptor Reflex ◽

Nerve Activity ◽

Renal Sympathetic Nerve Activity ◽

Conscious Rats ◽

Renal Sympathetic Nerve ◽

Renal Sympathetic

The effect of inhibition of nitric oxide (NO) synthesis on the responses of blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) during hemorrhaging was examined with the use of an NO synthase inhibitor, NG-nitro-l-arginine methyl ester (l-NAME), in conscious rats. In the 0.9% saline group, hemorrhage (10 ml/kg body wt) did not alter BP but significantly increased HR and RSNA by 88 ± 12 beats/min and 67 ± 12%, respectively. Intravenous infusion of l-NAME (50 μg ⋅ kg−1⋅ min−1) significantly attenuated these tachycardic and sympathoexcitatory responses to hemorrhage (14 ± 7 beats/min and 26 ± 12%, respectively). Pretreatment ofl-arginine (87 mg/kg) recovered the attenuation of HR and RSNA responses induced byl-NAME (92 ± 6 beats/min and 64 ± 10%, respectively).l-NAME by itself did not alter the baroreceptor reflex control of HR and RSNA. Hemorrhage increased the plasma vasopressin concentration, and its increment in thel-NAME-treated group was significantly higher than that in the 0.9% saline group. Pretreatment with the vascular arginine vasopressin V1-receptor antagonist OPC-21268 (5 mg/kg) recovered the attenuation of RSNA response induced byl-NAME (54 ± 7%). These results indicate that NO modulated HR and RSNA responses to hemorrhage but did not directly affect the baroreceptor reflex arch. It can be assumed that NO modulated the baroreflex function by altering the secretion of vasopressin induced by hemorrhage.

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Review for "Effects of intracerebroventricular leptin and orexin‐A on the baroreflex control of renal sympathetic nerve activity in conscious rats fed a normal or high‐fat diet"

10.1111/1440-1681.13451/v1/review1 ◽

2020 ◽

Author(s):

Peter Bie

Keyword(s):

Sympathetic Nerve ◽

High Fat Diet ◽

Sympathetic Nerve Activity ◽

High Fat ◽

Nerve Activity ◽

Orexin A ◽

Baroreflex Control ◽

Renal Sympathetic Nerve Activity ◽

Conscious Rats ◽

Renal Sympathetic

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Baroreflex control of lumbar and renal sympathetic nerve activity in conscious rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00147.2008 ◽

2008 ◽

Vol 295 (1) ◽

pp. R8-R14 ◽

Cited By ~ 9

Author(s):

Roy Kanbar ◽

Bruno Chapuis ◽

Valérie Oréa ◽

Christian Barrès ◽

Claude Julien

Keyword(s):

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

Baseline Period ◽

Nerve Activity ◽

Baroreflex Control ◽

Renal Sympathetic Nerve Activity ◽

Conscious Rats ◽

Renal Sympathetic Nerve ◽

Normalized Units ◽

Renal Sympathetic

This study compared the baroreflex control of lumbar and renal sympathetic nerve activity (SNA) in conscious rats. Arterial pressure (AP) and lumbar and renal SNA were simultaneously recorded in six freely behaving rats. Pharmacological estimates of lumbar and renal sympathetic baroreflex sensitivity (BRS) were obtained by means of the sequential intravenous administration of sodium nitroprusside and phenylephrine. Sympathetic BRS was significantly ( P < 0.05) lower for lumbar [3.0 ± 0.4 normalized units (NU)/mmHg] than for renal (7.6 ± 0.6 NU/mmHg) SNA. During a 219-min baseline period, spontaneous lumbar and renal BRS were continuously assessed by computing the gain of the transfer function relating AP and SNA at heart rate frequency over consecutive 61.4-s periods. The transfer gain was considered only when coherence between AP and SNA significantly differed from zero, which was verified in 99 ± 1 and 96 ± 3% of cases for lumbar and renal SNA, respectively. When averaged over the entire baseline period, spontaneous BRS was significantly ( P < 0.05) lower for lumbar (1.3 ± 0.2 NU/mmHg) than for renal (2.3 ± 0.3 NU/mmHg) SNA. For both SNAs, spontaneous BRS showed marked fluctuations (variation coefficients were 26 ± 2 and 28 ± 2% for lumbar and renal SNA, respectively). These fluctuations were positively correlated in five of six rats ( R = 0.44 ± 0.06; n = 204 ± 8; P < 0.0001). We conclude that in conscious rats, the baroreflex control of lumbar and renal SNA shows quantitative differences but is modulated in a mostly coordinated way.

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