Central and Baroreflex Control of Sympathetic Nerve Activity to the Heart and Kidney in a Daily Life of the Cat

Ninomiya, Ishio; Matsukawa, Kanji; Nishiura, Naoki

doi:10.3109/10641968809075961

Cited by 23 publications

(26 citation statements)

References 6 publications

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“…The reasons for the differences between our study and the one in conscious cats are unclear and it is possible that the difference may be attributed to the different species being studied. Our finding in conscious sheep that the sensitivity of the baroref lex control of CSNA is greater than that for RSNA confirms similar findings in the conscious cat (14) and anesthetized rabbit (15).…”

Section: Discussionsupporting

confidence: 80%

“…Anesthesia can inf luence the resting level of nerve activity as well as dampen baroref lex responses (12), and it is likely that the main differences between our study and other studies are because of anesthesia and perhaps the after effects of surgery. CSNA and RSNA have been recorded in conscious cats (2-6 days after surgery), but no consistent differences between their resting activity levels were observed (13,14). In our study, the animals were allowed at least three days to recover from surgery, after which resting arterial pressure and HR had reestablished their normal levels.…”

Section: Discussionmentioning

confidence: 99%

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Basis for the preferential activation of cardiac sympathetic nerve activity in heart failure

Ramchandra

Hood

Denton

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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In heart failure (HF) , sympathetic nerve activity is increased. Measurements in HF patients of cardiac norepinephrine spillover, reflecting cardiac sympathetic nerve activity (CSNA), indicate that it is increased earlier and to a greater extent than sympathetic activity to other organs. This has important consequences because it worsens prognosis, provoking arrhythmias and sudden death. To elucidate the mechanisms responsible for the activation of CSNA in HF, we made simultaneous direct neural recordings of CSNA and renal SNA (RSNA) in two groups of conscious sheep: normal animals and animals in HF induced by chronic, rapid ventricular pacing. In normal animals, the level of activity, measured as burst incidence (bursts of pulse related activity/100 heart beats), was significantly lower for CSNA (30 ؎ 5%) than for RSNA (94 ؎ 2%). Furthermore, the resting level of CSNA, relative to its maximum achieved while baroreceptors were unloaded by reducing arterial pressure, was set at a much lower percentage than RSNA. In HF, burst incidence of CSNA increased from 30 to 91%, whereas burst incidence of RSNA remained unaltered at 95%. The sensitivity of the control of both CSNA and RSNA by the arterial baroreflex remained unchanged in HF. These data show that, in the normal state, the resting level of CSNA is set at a lower level than RSNA, but in HF, the resting levels of SNA to both organs are close to their maxima. This finding provides an explanation for the preferential increase in cardiac norepinephrine spillover observed in HF.arterial baroreflex ͉ renal sympathetic nerve activity ͉ sheep H eart failure (HF) is associated with an increase in sympathetic nerve activity (SNA) that shows a large regional heterogeneity in the extent to which activity increases. The level of SNA to different organs may be estimated by measurements of regional norepinephrine (NE) spillover, and it has been observed that in HF there is a greater increase in NE spillover from the heart than the kidney, and no change from the gut (1, 2). This increase in cardiac NE spillover occurs at an earlier stage of HF than it does to other organs (3, 4), again suggesting a preferential stimulation of cardiac SNA (CSNA) in HF. The increase in CSNA in HF is detrimental as it can promote the progression of the disease and leads to development of arrhythmias and sudden death (5). The mechanisms accounting for the increase in CSNA in HF are poorly understood.One explanation for the preferential increase in cardiac NE spillover in HF is that, in the normal state, the resting levels of CSNA and renal SNA (RSNA) are similar, but in HF, sympathetic activity increases more to the heart than to the kidney. An alternative explanation is that the resting level of CSNA is set at a lower level compared with that to other organs, such the kidney, and in HF, both CSNA and RSNA increase to near maximum levels. Both explanations seem plausible, but the resting levels of CSNA and RSNA have not been simultaneously recorded in the normal state and compared with activities ...

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Basis for the preferential activation of cardiac sympathetic nerve activity in heart failure

Ramchandra

Hood

Denton

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…We found using this technique that CSNA increased during light body movement performed voluntarily, and the increase in CSNA occurred immediately before or simultaneously with the onset of body movement before an increase in HR (14,24). On the basis of these observations, we hypothesized that sympathetic outflow to the heart is stimulated during whole body dynamic exercise even though the exercise intensity is low to moderate, which in turn contributes to exerciseinduced tachycardia.…”

mentioning

confidence: 93%

“…Ninomiya et al (23,24) have developed a novel technique for recording CSNA in conscious cats. We found using this technique that CSNA increased during light body movement performed voluntarily, and the increase in CSNA occurred immediately before or simultaneously with the onset of body movement before an increase in HR (14,24).…”

mentioning

confidence: 99%

Direct measurement of cardiac sympathetic efferent nerve activity during dynamic exercise

Tsuchimochi

Matsukawa

Komine

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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The assumption that tachycardia during light to moderate exercise was predominantly controlled by withdrawal of cardiac parasympathetic nerve activity but not by augmentation of cardiac sympathetic nerve activity (CSNA) was challenged by measuring CSNA during treadmill exercise (speed, 10–60 m/min) for 1 min in five conscious cats. As soon as exercise started, CSNA and heart rate (HR) increased and mean arterial pressure (MAP) decreased; their time courses at the initial 12-s period of exercise were irrespective of the running speed. CSNA increased 168–297% at 7.1 ± 0.4 s from the exercise onset, and MAP decreased 8–13 mmHg at 6.0 ± 0.3 s, preceding the increase of 40–53 beats/min in HR at 10.5 ± 0.4 s. CSNA remained elevated during the later period of exercise, whereas HR and MAP gradually increased until the end of exercise. After the cessation of exercise, CSNA returned quickly to the control, whereas HR was slowly restored. In conclusion, cardiac sympathetic outflow augments at the onset of and during dynamic exercise even though the exercise intensity is low to moderate, which may contribute to acceleration of cardiac pacemaker rhythm.

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“…However, analysis of central rhythms, faster than or close to the cardiac cycle, in the awake animal is still lacking. The CSNA was influenced by behavioral stimuli (NINOMIYA et al, 1988a) and baroceptor reflex (NINOMIYA et al, 1988b).…”

mentioning

confidence: 99%

Fundamental rhythm of cardiac sympathetic nerve activity in awake cats at rest and during body movement.

Ninomiya¹,

Nishiura²,

Matsukawa³

et al. 1989

Jpn.J.Physiol

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Cardiac sympathetic nerve activity (CSNA in imp/s) was measured in the postganglionic fibers of awake cats at rest, during body movement, and with excitement. The CSNA showed synchronized discharges with various periodicities. Rhythms of the synchronized CSNA were analyzed by an interval histogram (IIH). The IIH showed a multimodal distribution. The first model interval (Ta) was in a range of 75 to 125 ms. An 8-12 cycle/s T~ rhythm, i.e., inverse value of T~, was always observed in the awake cat at rest and during body movements.

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Central and Baroreflex Control of Sympathetic Nerve Activity to the Heart and Kidney in a Daily Life of the Cat

Cited by 23 publications

References 6 publications

Basis for the preferential activation of cardiac sympathetic nerve activity in heart failure

Basis for the preferential activation of cardiac sympathetic nerve activity in heart failure

Direct measurement of cardiac sympathetic efferent nerve activity during dynamic exercise

Fundamental rhythm of cardiac sympathetic nerve activity in awake cats at rest and during body movement.

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