Factors controlling the regional differentiation of sympathetic outflow — influence of the chemoreceptor reflex

Iriki, Masami; Kozawa, Emi

doi:10.1016/0006-8993(75)90425-4

Cited by 32 publications

(13 citation statements)

References 18 publications

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“…We are not aware of any studies that have examined responses in LSNA to chemoreceptor stimulation previous to this study. Interestingly, arterial hypoxia leads to inhibition of cardiac SNA in the anesthetized rabbit (13,14) and the rat, as evidenced by a decrease in cardiac norepinephrine turnover (16). Thus, although our results showed no differential response in the RSNA and LSNA response, it does appear that moderate chemoreceptor stimulation leads to differential inhibition of cardiac SNA.…”

Section: Baroreflex and Chemoreflex Control Of Snacontrasting

confidence: 52%

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Ramchandra¹,

Barrett²,

Guild³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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We have explored the possibility that renal sympathetic nerve activity (RSNA) and vasomotor sympathetic nerve activity are differentially regulated. We measured sympathetic nerve activity (SNA) to the kidney and the hind limb vasculature in seven conscious rabbits 6 -8 days after the implantation of recording electrodes. Acute infusion of N G -nitro-Larginine methyl ester (L-NAME) (6 mg ⅐ kg Ϫ1 ⅐ min Ϫ1 for 5 min) led to an increase in blood pressure (from 66 Ϯ 1 to 82 Ϯ 3 mmHg) and a decrease in heart rate (from 214 Ϯ 15 to 160 Ϯ 13 bpm). L-NAME administration caused a significantly greater decrease in RSNA than lumbar sympathetic nerve activity (LSNA) (to 68 Ϯ 14% vs. 84 Ϯ 4% of control values, respectively). Volume expansion (1.5 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 ) resulted in a significant decrease in RSNA to 66 Ϯ 7% of control levels but no change in LSNA (127 Ϯ 20%). There was no difference in the gain of the baroreflex curves between the LSNA and RSNA [maximum gain of Ϫ7.6 Ϯ 0.4 normalized units (nu)/ mmHg for LSNA vs. Ϫ7.9 Ϯ 0.75 nu/mmHg for RSNA]. A hypoxic stimulus (10% O2 and 3% CO2) led to identical increases in both RSNA and LSNA (195 Ϯ 40% and 158 Ϯ 21% of control values, respectively). Our results indicate tailored differential control of RSNA and LSNA in response to acute stimuli. sympathetic activity; blood pressure EARLY CONCEPTS OF AUTONOMIC control suggested a global uniform activation of sympathetic nerve activity (SNA) to all organs in response to a "fight or flight" stimulus (3). The general convention was to refer to SNA as if the same signal travels to all organs, but this has been replaced with a more organized model that emphasizes differential control of sympathetic outflow to functionally specific targets (4, 22). Sympathetic nerve activity appears to be elevated in hypertension (9, 10), and half of the increase can be accounted for by increased norepinephrine spillover solely from the heart and the kidney (7,8). The selective increase in cardiac and renal sympathetic nerve activity (RSNA) indicates the importance of studying the differential control of nerve activity to better understand the control of blood pressure. The majority of evidence supporting differential control of SNA has come from anesthetized experiments in which sympathetic outflow to different organs in response to stimuli, such as volume expansion and baroreceptor stimulation, were measured.Studies in anesthetized rabbits have shown that volume expansion leads to an inhibition of RSNA (32). This reduction in RSNA with volume expansion appears to be differentially regulated compared with SNA to other nonrenal organs. Although volume expansion is also accompanied by a decrease in lumbar SNA (LSNA), this decrease appears to be differentially regulated compared with the RSNA response (33), although it must be mentioned that the two nerve activities were recorded in two separate sets of animals. It is pertinent to note that both of these studies were conducted in anesthetized rabbits. Recent studies have indicated that anesthesia can...

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Section: Baroreflex and Chemoreflex Control Of Snacontrasting

confidence: 52%

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Ramchandra¹,

Barrett²,

Guild³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Because the sympathetic nervous system has a characteristic regional differentiation, 13 it is possible that these correlations were not observed because MSNA regulating sympathetic tone into leg muscles was compared to MIBG uptake, which reflects the function of cardiac sympathetic neurons. Another possible explanation for the missing correlation between H/M ratio and MSNA is that MIBG uptake is already very low at early stages of the disease and, therefore, cannot decrease anymore over time.…”

Section: Discussionmentioning

confidence: 97%

Analysis of the relationship between muscle sympathetic nerve activity and cardiac ¹²³I‐metaiodobenzylguanidine uptake in patients with Parkinson's disease

et al. 2005

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To analyze the correlation between muscle sympathetic nerve activity (MSNA) and cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake in patients with Parkinson's disease (PD), we measured both parameters in 14 PD patients who were 51 to 82 years of age (mean, 63.1 +/- 8.7 years). The duration of PD was 2 to 26 years, and the disability level (modified Hoehn and Yahr stage) ranged from 2.0 to 4.0 (mean, 3.2 +/- 0.5). MSNA was recorded from the peroneal nerve fascicles using microneurographic methods, and then cardiac MIBG scintigraphy was performed within 1 month. We analyzed the correlation between the standardized MSNA, expressed as a percentage of the predicted value based on control subject data, and the heart-to-mediastinum ratio (H/M) or washout ratio (WR) from early and delayed MIBG images. The relationships between disease duration or disability and MSNA, the H/M ratio, or the WR were also analyzed. No significant correlations were found between MSNA and H/M ratio or WR. Although MSNA was inversely correlated with disease duration and with disability level, neither the H/M ratio nor the WR showed a significant correlation with disease duration or disability level. Because MSNA and MIBG abnormalities were not related, functional changes in addition to organic changes in cardiac sympathetic nerve endings may result in abnormal uptake of MIBG in Parkinson's disease. .

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“…Some studies have suggested that sympathetic premotor neurons for cutaneous vasoconstrictors are located in the RVLM, at sites medial to the RVLM or nucleus raphé of the medulla (13,18,20,24,26). Chemoreceptor stimulation or hypoxia inhibits activity of cutaneous vasoconstrictors, including the supply to the rabbit's ear, which is a specialized heat exchanger (7,9). Premotor neurons may also be inhibited by hypoxia.…”

Section: Discussionmentioning

confidence: 99%

“…However, it has been known that hypoxia produces different responses in sympathetic nerves. For example, hypoxia induces inactivation of cutaneous vasoconstrictors in cats, rats, and rabbits (7,9). Furthermore, at least in the rabbit, hypoxia induces bradycardia through the inhibition of the activity of the cardiac sympathetic nerve (10).…”

mentioning

confidence: 99%

Differential responsiveness of RVLM sympathetic premotor neurons to hypoxia in rabbits

Koganezawa¹,

Terui²

2007

American Journal of Physiology-Heart and Circulatory Physiology

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Koganezawa T, Terui N. Differential responsiveness of RVLM sympathetic premotor neurons to hypoxia in rabbits. Am J Physiol Heart Circ Physiol 292: H408 -H414, 2007. First published September 22, 2006; doi:10.1152/ajpheart.00881.2006.-To determine whether differential sympathetic nerve responses to hypoxia are explained by opposing effects of hypoxia upon sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM), the cardiac sympathetic nerve and the renal sympathetic nerve were recorded in anesthetized and vagotomized rabbits. Renal sympathetic nerve was activated by the injection of sodium cyanide solution close to the bifurcation of the common carotid artery and/or by inhalation of hypoxic gas (3% oxygen-97% nitrogen). On the other hand, cardiac sympathetic nerve was inhibited by these stimuli. Barosensitive (inhibited by the stimulation of baroreceptor afferents) reticulospinal (antidromically activated by the stimulation of the spinal cord) neurons in the RVLM were divided into three groups according to their responses to hypoxic stimulation: neurons (Type I, n ϭ 25), the activity of which was inhibited by the injection of sodium cyanide solution close to the bifurcation of the common carotid artery and/or by inhalation of hypoxic gas, neurons (Type II, n ϭ 99), the activity of which was facilitated by the same stimulation, and neurons (Type III, n ϭ 11), the activity of which was not changed. These data indicated that the differential responses of cardiac and renal sympathetic nerves might be due to opposing effects of hypoxia on individual RVLM neurons. rostral ventrolateral medulla; cardiac sympathetic nerve; renal sympathetic nerve; chemoreceptor; regional different response PREMOTOR NEURONS for cardiovascular sympathetic nerves are located in the rostral ventrolateral medulla (RVLM) and have been called RVLM neurons (6,8,15). In almost all of the previous papers, the consensus is that RVLM neurons have tonic activity; receive information from baroreceptors, chemoreceptors, and other peripheral and central sources; and control vasoconstrictors and cardiac sympathetic nerve activity (CSNA) that control heart function and arterial pressure (15). Because the activities of cardiac accelerators and vasoconstrictors usually proceed in the same direction, for instance, in the case of the baroreceptor reflex, it has not been established whether a single premotor neuron innervates both of the preganglionic neurons of cardiac accelerators and vasoconstrictors or premotor neurons differentially control functionally different target neurons.Generally, a hypoxic stimulation is believed to excite sympathetic nerves, as well as visceral vasoconstrictors and muscle vasoconstrictors (12). However, it has been known that hypoxia produces different responses in sympathetic nerves. For example, hypoxia induces inactivation of cutaneous vasoconstrictors in cats, rats, and rabbits (7, 9). Furthermore, at least in the rabbit, hypoxia induces bradycardia through the inhibition of the activity of the cardiac sym...

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Factors controlling the regional differentiation of sympathetic outflow — influence of the chemoreceptor reflex

Cited by 32 publications

References 18 publications

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Analysis of the relationship between muscle sympathetic nerve activity and cardiac ¹²³I‐metaiodobenzylguanidine uptake in patients with Parkinson's disease

Differential responsiveness of RVLM sympathetic premotor neurons to hypoxia in rabbits

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Factors controlling the regional differentiation of sympathetic outflow — influence of the chemoreceptor reflex

Cited by 32 publications

References 18 publications

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits

Analysis of the relationship between muscle sympathetic nerve activity and cardiac 123I‐metaiodobenzylguanidine uptake in patients with Parkinson's disease

Differential responsiveness of RVLM sympathetic premotor neurons to hypoxia in rabbits

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Analysis of the relationship between muscle sympathetic nerve activity and cardiac ¹²³I‐metaiodobenzylguanidine uptake in patients with Parkinson's disease