Differential effect of behavior on cardiac and vasomotor baroreflex responses

Combs, C. Andrew; Smith, Orville A.; Astley, C. A.; Feigl, Eric O.

doi:10.1152/ajpregu.1986.251.1.r126

Cited by 8 publications

(9 citation statements)

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“…When baroreflex sensitivity was assessed as a ratio of the change in R-R interval or HR in response to an alteration in AP, it was reduced during dynamic or static exercise in humans (3,14) and dogs (25). In addition, the response in R-R interval or HR to a change in carotid sinus transmural pressure was blunted during dynamic or static exercise in humans (18,19,47) and baboons (5), although Bevegård and Shephard (2) reported that a reflex decrease in HR in response to neck suction was similar during rest and exercise. On the other hand, the responses in AP to neck pressure and suction were less affected or preserved during exercise (2,8,18,47).…”

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confidence: 99%

Central command blunts the baroreflex bradycardia to aortic nerve stimulation at the onset of voluntary static exercise in cats

Komine

Matsukawa

Tsuchimochi

et al. 2003

American Journal of Physiology-Heart and Circulatory Physiology

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Komine, Hidehiko, Kanji Matsukawa, Hirotsugu Tsuchimochi, and Jun Murata. Central command blunts the baroreflex bradycardia to aortic nerve stimulation at the onset of voluntary static exercise in cats. Am J Physiol Heart Circ Physiol 285: H516-H526, 2003. First published May 1, 2003 10.1152/ajpheart.00013.2003.-To examine whether the central characteristics of the aortic baroreflex alter from moment to moment during static exercise, we identified the dynamic changes in the sizes of the bradycardia and depressor response evoked by stimulation of the aortic depressor nerve (ADN). Three conscious cats were trained to voluntarily extend the right forelimb and press a bar for 31 Ϯ 1 s with a peak force of 337 Ϯ 22 g while maintaining a sitting posture. The ADN stimulation-induced bradycardia was attenuated at the initial period of exercise (up to 8 s from the exercise onset) to 62 Ϯ 5% of the preexercise bradycardia and remained blunted until the end of exercise. The most blunted bradycardia was observed immediately before or when the forelimb was extended before force development. The baroreflex-induced bradycardia was suppressed again at cessation of exercise when the forelimb was retracted and recovered within a few seconds. In contrast, static exercise did not affect the ADN stimulation-induced depressor response. The ADN stimulation-induced bradycardia was also blunted at the beginning of naturally occurring body movement such as spontaneous postural change or grooming behavior. Thus it is likely that the central characteristics of the aortic baroreflex dynamically change from moment to moment during voluntary static exercise and during natural body movement and that particularly a central inhibition of the cardiac component of the aortic baroreflex is induced by central command at the onset of static exercise, whereas the central property of the vasomotor component of the baroreflex is preserved.aortic depressor nerve; aortic baroreceptors; baroreflex sensitivity; baroreflex depressor response; central modulation of the arterial baroreflex ARTERIAL BLOOD PRESSURE (AP) is sensed by arterial baroreceptors in the carotid sinus and aortic arch regions, whose activities transmit the beat-to-beat changes in AP to the central nervous system and evoke the baroreflex responses of autonomic efferent nerve activities to the heart and blood vessels. For example, if AP increases during resting, arterial baroreceptors are stimulated in proportion to the rise in AP, which elicits reflex bradycardia and depressor response and thereby restores AP to the control level. However, it is well known that heart rate (HR) and AP increase simultaneously during static or dynamic exercise in humans and conscious animals, indicating that arterial baroreflex function is modulated by exercise.The effect of exercise on the arterial baroreflexes has been extensively studied in humans and animals. When baroreflex sensitivity was assessed as a ratio of the change in R-R interval or HR in response to an alteration in AP, it was reduced during d...

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Central command blunts the baroreflex bradycardia to aortic nerve stimulation at the onset of voluntary static exercise in cats

Komine

Matsukawa

Tsuchimochi

et al. 2003

American Journal of Physiology-Heart and Circulatory Physiology

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“…The baboons were conditioned to this study system for at least 1 month before operation, and all studies were performed with animals sitting quietly in an upright position. 10 Systemic arterial pressure was recorded continuously using a pressure transducer (Model 4-327-1, Bell and HoweU, Pasadena, CA, USA) positioned at the midthoracic level and connected to a chart recorder (Neotrace 600, Neomedix Systems, Sydney, Australia). HR was calculated from the pulse interval of the phasic arterial pressure tracings, recorded at a paper speed of 25 mm/sec.…”

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confidence: 99%

Effect of angiotensin II on baroreceptor reflex control of heart rate in conscious baboons.

et al. 1987

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SUMMARY Studies of the baroreceptor-heart rate reflex were performed in four conscious, unrestrained male baboons to determine whether changes in circulating angiotensin II within the physiological range are associated with alterations in baroreceptor reflex sensitivity. With the animals on a high sodium intake, studies were performed before and during graded angiotensin II infusion (10 and 20 ng/kg/min). To separate effects on baroreceptor reflex function mediated by angiotensin H-induced increases in arterial pressure, these studies were repeated on a different day with simultaneous glyceryl trinitrate infusion to prevent increases in pressure during angiotensin II infusion. With the animals on a low sodium intake, studies were performed before and after angiotensin converting enzyme inhibition with captopril (1 and 5 mg/kg). These studies were also repeated on a separate day during simultaneous phenylephrine infusion to prevent a decrease in pressure with captopril. Reduction in sodium intake had no significant effect on arterial pressure, heart rate, or plasma volume, although arterial plasma angiotensin II concentration and renin activity were significantly increased (p<0.01). Infusion of angiotensin II produced a significant reduction in baroreceptor reflex sensitivity (p<0.01), and converting enzyme inhibition produced a significant increase (p<0.05). These effects accompanied significant increases and decreases in arterial angiotensin II concentration, respectively (p<0.01), but were independent of angiotensin Il-related changes in arterial pressure. The data indicate that physiological variations in circulating angiotensin II have a direct effect on sensitivity of the baroreceptor-heart rate reflex. (Hypertension 10: 628-634, 1987) KEY WORDS • angiotensin • captopril • baboon • baroreceptor reflex • converting enzyme inhibitor • heart rate T HE role of angiotensin II (Ang II) in cardiovascular homeostasis extends beyond its direct vasoconstrictor effect and its stimulation of aldosterone secretion. There is a complex interaction between the renin-angiotensin system and the autonomic nervous system in control of the circulation that involves both direct sympathetic effects on renal renin release 1 and positive feedback by Ang II on the autonomic nervous system at peripheral and central sites.2 -3 In particular, Ang II may modulate baroreceptor reflex control of heart rate (HR). Reflex bradycardia is less pronounced in response to Ang II-induced From the

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“…ADN electrical stimulation gave the most robust, consistent baroreflex activation, and EEG ␦ is a commonly accepted index of "slow-wave" or "quiet" sleep 2 ; given this, our analyses were based on the relationship between EEG ␦ and the responses to the ADN test stimuli 3 .…”

Section: Methodsmentioning

confidence: 99%

“…1, 6, and 11 of Ref.7). 3 Having included the results of sinus stimulation, other EEG measures, or the three additional rats (DU, EC, and EG) described in Refs. 8 and 9 would not have substantially changed any of the results: for all five rats, for both the ADN electrode and sinus balloon stimulation, neither HP nor BP measures of the baroreflex gain ratio were dependent on the EEG or EEG␤ amplitude.…”

Section: Methodsmentioning

confidence: 99%

“…That HP might not correlate well with the net baroreflex depressor action was first suggested in chronic dog studies using implanted carotid sinus nerve stimulators, which, during sleep, produced 12-22% greater bradycardia but no change in the net BP depressor effect (31). Similarly, in baboons, using carotid occlusion to inhibit the baroreceptors, Combs et al (3) found that during sleep, compared with the awake resting state, changes in HP increased, in lower abdominal conductance remained the same, and in renal conductance decreased.…”

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confidence: 98%

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Baroreflexes of the rat. III. Open-loop gain and electroencephalographic arousal

Dworkin¹,

Dworkin²

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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In early studies of humans, baroreflex sensitivity was found to be higher during sleep; however, subsequent observations in several species, including humans, have been at variance with the original reports. Sleep and arousal are behavioral states, and it is difficult to accurately and repeatedly measure baroreflex sensitivity in behaving animals. However, pharmacologically immobilized (neuromuscularly blocked) rats have apparently normal sleep-wakefulness cycles, and baroreflex gain can be measured directly in this preparation. Using the delta band of the EEG (EEG(delta)) as an index of sleep and arousal and open-loop aortic depressor nerve (ADN) stimulation as a baroreflex input, we found that blood pressure (BP) level depended on arousal (r = -0.416; P < 0.0001), and BP baroreflex gain depended on BP level (r = 0.496; P < 0.0001), but that BP baroreflex gain was independent of arousal (r = 0.001; NS). Heart period (HP) was different; although HP level depended on arousal (r = 0.352; P < 0.0001), HP baroreflex gain did not depend on HP level (r = 0.029; NS), and HP baroreflex gain increased with arousal (r = 0.315; P < 0.0001). A partial-correlations analysis showed that the presence of the relationship between BP level and BP baroreflex gain probably attenuated the relationship between arousal and BP gain. The results are consistent 1) with physiological findings showing that arousal attenuates afferent transmission through the nucleus of the solitary tract and enhances sympathoinhibition at the rostral ventrolateral medulla; and 2) with observations in humans and animals showing increased cardiac baroreflex sensitivity during sleep, but little if any effect of sleep on BP baroreflex sensitivity. The findings are relevant to all methods of baroreflex gain estimation that use HP as the index of baroreflex activation.

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Differential effect of behavior on cardiac and vasomotor baroreflex responses

Cited by 8 publications

References 0 publications

Central command blunts the baroreflex bradycardia to aortic nerve stimulation at the onset of voluntary static exercise in cats

Central command blunts the baroreflex bradycardia to aortic nerve stimulation at the onset of voluntary static exercise in cats

Effect of angiotensin II on baroreceptor reflex control of heart rate in conscious baboons.

Baroreflexes of the rat. III. Open-loop gain and electroencephalographic arousal

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