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

2003 ◽  
Vol 285 (2) ◽  
pp. H516-H526 ◽  
Author(s):  
Hidehiko Komine ◽  
Kanji Matsukawa ◽  
Hirotsugu Tsuchimochi ◽  
Jun Murata
Keyword(s):  
Initial Period ◽  
Body Movement ◽  
Central Command ◽  
Static Exercise ◽  
Sitting Posture ◽  
Depressor Response ◽  
Aortic Depressor Nerve ◽  
Central Inhibition ◽  
Cardiac Component ◽  
The Right

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 ± 1 s with a peak force of 337 ± 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 ± 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 The baroreflex-induced bradycardia was suppressed again at cessation of exercise when the forelimb was retracted and recovered within a few seconds.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.

Central command blunts sensitivity of arterial baroreceptor-heart rate reflex at onset of voluntary static exercise

2006 ◽  
Vol 290 (1) ◽  
pp. H200-H208 ◽  
Author(s):  
Kanji Matsukawa ◽  
Hidehiko Komine ◽  
Tomoko Nakamoto ◽  
Jun Murata
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Response Curve ◽  
Central Command ◽  
Arterial Baroreflex ◽  
Static Exercise ◽  
Response Curves ◽  
Stimulus Response ◽  
Aortic Depressor Nerve ◽  
Blood Pressures

We have reported that baroreflex bradycardia by stimulation of the aortic depressor nerve is blunted at the onset of voluntary static exercise in conscious cats. Central command may contribute to the blunted bradycardia, because the most blunted bradycardia occurs immediately before exercise or when a forelimb is extended before force development. However, it remained unknown whether the blunted bradycardia is due to either reduced sensitivity of the baroreflex stimulus-response curve or resetting of the curve toward a higher blood pressure. To determine this, we examined the stimulus-response relationship between systolic (SAP) or mean arterial pressure (MAP) and heart rate (HR) at the onset of and during the later period of static exercise in seven cats ( n = 348 trials) by changing arterial pressure with infusion of nitroprusside and phenylephrine or norepinephrine. The slope of the MAP-HR curve decreased at the onset of exercise to 48% of the preexercise value (2.9 ± 0.4 beats·min−1·mmHg−1); the slope of the SAP-HR curve decreased to 59%. The threshold blood pressures of the stimulus-response curves, at which HR started to fall due to arterial baroreflex, were not affected. In contrast, the slopes of the stimulus-response curves during the later period of exercise returned near the preexercise levels, whereas the threshold blood pressures elevated 6–8 mmHg. The maximal plateau level of HR was not different before and during static exercise, denying an upward shift of the baroreflex stimulus-response curves. Thus central command is likely to attenuate sensitivity of the cardiac component of arterial baroreflex at the onset of voluntary static exercise without shifting the stimulus-response curve.

Aortic depressor fibers in the rat: an electrophysiological study

1963 ◽  
Vol 205 (4) ◽  
pp. 771-774 ◽  
Author(s):  
Eduardo Moacyr Krieger ◽  
Ricardo Francisco Marseillan
Keyword(s):  
Action Potential ◽  
Electrophysiological Study ◽  
Sympathetic Trunk ◽  
Cervical Region ◽  
Laryngeal Nerves ◽  
Aortic Depressor Nerve ◽  
Aortic Nerve ◽  
Msec Duration ◽  
The Right

In 51 rats the distribution of the aortic depressor fibers which travel in the cervical region with the vagus, sympathetic, laryngeal, or as a separate aortic nerve was investigated by recording the action potential or by stimulating these nerves. A separate aortic depressor nerve was found in only 20% of the rats on the left side and in 5% on the right side. In these animals no depressor fibers were identified in the sympathetic trunk but the laryngeal nerves usually still exhibited depressor fiber activity. In those rats with no separate aortic depressor nerve the aortic fibers were present almost equally in the sympathetic trunk and laryngeal nerves, and on both sides of the neck. Only exceptionally was depressor activity found in the vagus trunk, and stimulation elicited depressor instead of pressor effects in 2 out of 12 rats. Optimal stimuli for obtaining hypotensive effects from the aortic depressor fibers were 80–150 per frequency and 1–2-msec duration.

Differential contribution of central command to the cardiovascular responses during static exercise of ankle dorsal and plantar flexion in humans

2011 ◽  
Vol 110 (3) ◽  
pp. 670-680 ◽  
Author(s):  
Nan Liang ◽  
Tomoko Nakamoto ◽  
Seina Mochizuki ◽  
Kanji Matsukawa
Keyword(s):  
Stroke Volume ◽  
Total Peripheral Resistance ◽  
Plantar Flexion ◽  
Peripheral Resistance ◽  
Cardiovascular Responses ◽  
Central Command ◽  
Static Exercise ◽  
Maximum Increase ◽  
Arterial Blood ◽  
Differential Contribution

To examine whether central command contributes differently to the cardiovascular responses during voluntary static exercise engaged by different muscle groups, we encouraged healthy subjects to perform voluntary and electrically evoked involuntary static exercise of ankle dorsal and plantar flexion. Each exercise was conducted with 25% of the maximum voluntary force of the right ankle dorsal and plantar flexion, respectively, for 2 min. Heart rate (HR) and mean arterial blood pressure (MAP) were recorded, and stroke volume, cardiac output (CO), and total peripheral resistance were calculated. With voluntary exercise, HR, MAP, and CO significantly increased during dorsal flexion (the maximum increase, HR: 12 ± 2.3 beats/min; MAP: 14 ± 2.0 mmHg; CO: 1 ± 0.2 l/min), whereas only MAP increased during plantar flexion (the maximum increase, 6 ± 2.0 mmHg). Stroke volume and total peripheral resistance were unchanged throughout the two kinds of voluntary static exercise. With involuntary exercise, there were no significant changes in all cardiovascular variables, irrespective of dorsal or plantar flexion. Furthermore, before the force onset of voluntary static exercise, HR and MAP started to increase without muscle contraction, whereas they had no significant changes with involuntary exercise at the moment. The present findings indicate that differential contribution of central command is responsible for the different cardiovascular responses to static exercise, depending on the strength of central control of the contracting muscle.

scholarly journals Constructing the Ideology of the Right-Wing Radical Party in Modern United Kingdom: The Case of the United Kingdom Independence Party

2021 ◽  
Vol 23 (3) ◽  
pp. 446-462
Author(s):  
Mikhail S. Golovin
Keyword(s):  
United Kingdom ◽  
Initial Period ◽  
British Society ◽  
Right Wing ◽  
The European Union ◽  
Political Struggle ◽  
Frequent Change ◽  
Cultural Conditions ◽  
The United Kingdom ◽  
The Right

This article examines the update of ideological foundations of the largest right-wing radical party in Britain (and in the whole of Europe) - the United Kingdom Independence Party (UKIP). The subject of the research is the partys programmatic text, Manifesto for Brexit and Beyond, a document that is not limited to the discussion of Brexit alone. This document appeared at the end of 2019 and, despite the frequent change of leadership in the party during 2020, remained the ideological foundation of the organization after Brexit. The aim of the article is to analyze how the ideological base of the right-wing British radical party was formed in the socio-political realities of the initial period after the states exit from the European Union. The paper presents a discursive analysis of the main ideological document of one of UKIP, as well as identifies the ideological positions of British right-wing radicals at the present stage. Since the research is mainly practice-oriented, the main results are presented the data obtained through discourse analysis using to the method of R. Wodak. The data testify the changes that have been taking place in the discourse of the extreme right in Britain in recent years, as well as the prospects for its evolution in the coming years after Brexit. Studying UKIPs discourse, the author concludes that it forms depending on the political, social and cultural conditions that prevail in modern British society, as well as on the general European context. The article also shows how a modern right-wing radical party constructs its discourse using the most painful issues for the society within the framework of political struggle.

Cardiac Helical Function

2020 ◽  
Author(s):  
Jorge Trainini ◽  
Jorge Lowenstein ◽  
Mario Beraudo ◽  
Mario Wernicke ◽  
Vicente Mora Llabata ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Initial Period ◽  
Three Dimensional ◽  
Electrical Activation ◽  
Histological Structure ◽  
Great Resistance ◽  
Diastolic Phase ◽  
The Right ◽  
Ventricular Twist ◽  
Ventricular Filling

Abstract Background. The aim of this study was to investigate: a) the starts and ends of the myocardial band; b) the slippage between the band segments, when performing both torsion and ventricular detorsion, implies that there should be an antifriction mechanism that avoids dissipating the energy; c) the electrical activation of the endocardial and epicardial bands and secondarily understand ventricular twist and the mechanism of active suction during the diastolic isovolumic phase. Methods. They were used: a) Ten young-bovine hearts (800-1000 g) and seven human hearts (one embrión, 4 g; one 10 years, 250 g and five adult, 300 g/average); b) five patients with no structural cardiac abnormalities and normal QRS complexes underwent three-dimensional endoepicardial electroanatomic mapping. Results. We have found in all the bovine and human hearts studied a nucleus (fulcrum) underlying the right trigone, whose osseus, chondroid or tendinous histological structure depends on the specimen analyzed. All the hearts studied presented myocardial attachment to the rigid structure of the fulcrum. Hyaluronic acid was found in the cleavage planes between the myocardial bundles.Endo-epicardial mapping demonstrates an electrical activation sequence in the area of the apex loop in agreement with the synchronic contraction of the descending and ascending band segments, consistent with the mechanism of ventricular twist. The late activation of the ascending band segment is consistent with its persistent contraction during the initial period of the isovolumic diastolic phase (the basis of the suction mechanism). Conclusions. The finding of the fulcrum gives support to the spiral myocardial band being the point of fixation that allows the helicoidal torsion. The hyaluronic acid would act as a lubricant and provide great resistance to mechanical pressures. This study explains the ventricular twist and the active suction mechanism during the isovolumic diastolic and early ventricular filling phases.Trial. This work does not correspond to a trial

Dynamic transduction properties of in situ baroreceptors of rabbit aortic depressor nerve

1998 ◽  
Vol 274 (1) ◽  
pp. H358-H365 ◽  
Author(s):  
Takayuki Sato ◽  
Toru Kawada ◽  
Toshiaki Shishido ◽  
Hiroshi Miyano ◽  
Masashi Inagaki ◽  
...  
Keyword(s):  
Transfer Function ◽  
White Noise ◽  
Innominate Artery ◽  
Operating Pressure ◽  
Frequency Range ◽  
Aortic Depressor Nerve ◽  
The Right ◽  
Common Carotid Arteries ◽  
Made In

We developed a new method for isolating in situ baroreceptor regions of the rabbit aortic depressor nerve (ADN) and estimated the transfer function from pressure to afferent nerve activity in the frequency range of 0.01–5 Hz by a white noise technique. Complete isolation of the baroreceptor area of the right ADN was made in situ by ligation of the innominate artery and the right subclavian and common carotid arteries. We altered the pressure in the isolated baroreceptor area according to a binary quasi-white noise between 80 and 100 mmHg in 12 urethan-anesthetized rabbits. The gain increased two to three times as the frequency of pressure perturbation increased from 0.01 to 2 Hz and then decreased at higher frequencies. The phase slightly led below 0.2 Hz. The squared coherence value was >0.8 in the frequency range of 0.01–4 Hz. The step responses estimated from the transfer function were indistinguishable from those actually observed. We conclude that the baroreceptor transduction of the ADN is governed by linear dynamics under the physiological operating pressure range.

Acute resetting of the carotid sinus baroreflex by aortic depressor nerve stimulation

1993 ◽  
Vol 264 (4) ◽  
pp. H1215-H1222 ◽  
Author(s):  
L. Hayward ◽  
M. Hay ◽  
R. B. Felder
Keyword(s):  
Sympathetic Nerve Activity ◽  
Carotid Sinus ◽  
Renal Sympathetic Nerve Activity ◽  
Aortic Depressor Nerve ◽  
Central Neurons ◽  
Carotid Sinus Baroreflex ◽  
Before And After ◽  
The Right ◽  
Sinus Pressure ◽  
Renal Sympathetic

The effect of prolonged aortic depressor nerve (ADN) stimulation on carotid sinus baroreflex regulation of arterial pressure (AP) and renal sympathetic nerve activity (RSNA) was examined in anesthetized rabbits. Ramp increases in carotid sinus pressure (CSP) were repeated before and after 5 min of bilateral ADN stimulation. One minute after ADN stimulation the curve relating AP to CSP had shifted up and to the right, characterized by significant increases (P < 0.05) in the maximum (91 +/- 2 to 101 +/- 3 mmHg; mean +/- SE), midpoint (118 +/- 7 to 125 +/- 8 mmHg CSP), and minimum (45 +/- 3 to 53 +/- 4 mmHg) of the AP reflex curve. There was a parallel shift downward of the curve relating RSNA to CSP, characterized by significant decreases in the maximum [100 +/- 0 to 66 +/- 8% of maximum control RSNA value (%max)], the range (90 +/- 2 to 59 +/- 8%max), and the gain (-1.0 +/- 0.2 to -0.5 +/- 0.1%max/mmHg) of the RSNA reflex curve. Values returned to control within 10 min of cessation of ADN stimulation. These results suggest that central neurons processing baroreflex information from one set of mechanoreceptors can be reset by convergent signals arising from another baroreceptor site.

EFFECTS OF CENTRAL COMMAND ON CAROTID BAROREFLEX FUNCTION DURING STATIC EXERCISE IN HUMANS

2002 ◽  
Vol 34 (5) ◽  
pp. S112
Author(s):  
S Ogoh ◽  
D Keller ◽  
R Vinson ◽  
W Wasmund ◽  
A H. Olivencia-Yurvati ◽  
...  
Keyword(s):  
Central Command ◽  
Static Exercise ◽  
Baroreflex Function ◽  
Carotid Baroreflex ◽  
Exercise In Humans

Transient middle cerebral artery occlusion and reperfusion alters inducible NOS expression within the ventrolateral medulla and modulates cardiovascular function during static exercise

2011 ◽  
Vol 89 (9) ◽  
pp. 639-646 ◽  
Author(s):  
Ahmmed Ally ◽  
Timothy J. Maher
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cardiovascular Function ◽  
Cardiovascular Responses ◽  
Inos Expression ◽  
Ventrolateral Medulla ◽  
Static Exercise ◽  
Inos Protein ◽  
The Right ◽  
Inducible Nos

A major cause of stroke is cerebral ischemia in regions supplied by the middle cerebral artery (MCA). In this study, we hypothesized that compromised cardiovascular function during static exercise may involve altered expression of inducible NOS (iNOS) protein within the rostral ventrolateral medulla (RVLM) and caudal ventrolateral medulla (CVLM). We compared cardiovascular responses and iNOS protein expression within the left and right sides of both RVLM and CVLM in sham-operated rats and in rats with a 90 min left-sided MCA occlusion (MCAO) followed by 24 h of reperfusion. Increases in blood pressure during a static muscle contraction were attenuated in MCAO rats compared with sham-operated rats. Also, iNOS expression within the left RVLM was augmented compared with the right RVLM in MCAO rats and compared with both RVLM quadrants in sham-operated rats. In contrast, compared with sham-operated rats and the right CVLM of MCAO rats, iNOS expression was attenuated in the left CVLM in left-sided MCAO rats. These data suggest that the attenuation of pressor responses during static exercise in MCAO rats involves overexpression of iNOS within the ipsilateral RVLM and attenuation in iNOS within the ipsilateral CVLM. Differential expression of iNOS within the medulla plays a role in mediating cardiovascular responses during static exercise following stroke.

Sign in / Sign up

Export Citation Format

Share Document