Dexamethasone attenuates the modulatory effect of the insular cortex on the baroreflex in anesthetized rat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2021-0385 ◽

2021 ◽

Author(s):

Tatiana Sergeevna Tumanova ◽

Tatiana Nikolaevna Кokurina ◽

Galina Ivanovna Rybakova ◽

Viacheslav G. Aleksandrov

Keyword(s):

Arterial Pressure ◽

Baroreflex Sensitivity ◽

Insular Cortex ◽

Neural Mechanism ◽

Arterial Baroreflex ◽

Inhibitory Effects ◽

Short Term ◽

Central Autonomic Network

The arterial baroreflex (BR) is an important neural mechanism for the stabilization of arterial pressure (AP). It is known that the insular cortex (IC) and other parts of the central autonomic network (CAN) are able to modulate the BR arc, altering baroreflex sensitivity (BRS). In addition, the sensitivity of the BR changes under the influence of hormones, in particular glucocorticoids (GC). It has been suggested that GC may influence BRS by altering the ability of the IC to modulate the BR. This hypothesis has been tested in experiments on rats anesthetized with urethane. It was found that microelectrostimulation of the visceral area in the left IC causes a short-term drop in AP, which is accompanied by bradycardia, and impairs BRS. The synthetic GC dexamethasone (DEX) did not significantly affect the magnitude of depressor responses but increased BRS and impaired the effect of IC stimulation on the BR. The results obtained confirm the hypothesis put forward and suggest that GC can attenuate the inhibitory effects of the IC on the BR arc, thereby enhancing the sensitivity of the BR.

Download Full-text

Rapid resetting of baroreflexes in hypertensive dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1992.262.5.h1508 ◽

1992 ◽

Vol 262 (5) ◽

pp. H1508-H1514

Author(s):

M. J. Brunner ◽

M. D. Kligman

Keyword(s):

Heart Rate ◽

Arterial Pressure ◽

Carotid Sinus ◽

Experimental Hypertension ◽

Arterial Baroreflex ◽

Short Term ◽

Baroreflex Control ◽

Pentobarbital Sodium ◽

Reflex Gain ◽

Pentobarbital Sodium Anesthesia

The hypothesis tested was that the rapid resetting of the arterial baroreflex control of arterial pressure in normotension could be demonstrated in experimental hypertension. After the development of experimental hypertension (using a bilateral renal wrap technique), rapid resetting of arterial pressure and heart rate (HR) was acutely assessed under pentobarbital sodium anesthesia in hypertensive and normotensive vagotomized dogs. The carotid sinus area was isolated and perfused at controlled carotid sinus pressures (CSPs). Baroreflex response [mean arterial pressure (MAP) and HR] curves were measured after three carotid sinus conditioning pressures (50, 125, and 200 mmHg) were applied. For the MAP response, the CSPo (CSP at point of maximum reflex gain) increased significantly to the same extent in both groups with increasing conditioning pressures (with 22.2 and 16.7% resetting in the normotensive group, and 20.3 and 14.2% resetting in the hypertensive group). We conclude that short-term adjustments to changes in prevailing pressure (rapid resetting) occur in the arterial pressure response in experimental hypertension to the same extent seen in normotension.

Download Full-text

Abstract 413: Electroacupuncture Improves Arterial Baroreflex and Chemoreflex Sensitivity in Angiotensin II-induced Hypertension in Rats

Hypertension ◽

10.1161/hyp.60.suppl_1.a413 ◽

2012 ◽

Vol 60 (suppl_1) ◽

Author(s):

Qi Zhang ◽

Yingying Tan

Keyword(s):

Arterial Pressure ◽

Baroreflex Sensitivity ◽

Saline Control ◽

Control Group ◽

Sensitivity Index ◽

Ang Ii ◽

Arterial Baroreflex ◽

Induced Hypertension ◽

Chemoreflex Sensitivity ◽

Stimulation Of

Despite the use of electroacupuncture (EA) to treat a number of cardiovascular diseases, little is known about the mechanisms that underlie its actions. It is well known that renin-angiotensin system plays a major role in pathogenesis of hypertension. The purpose of this study was to examine the influence of EA stimulation of ST 36 on arterial baro- and chemoreflex sensitivity in angiotensin (Ang) II-induced hypertension in rats. Four groups of SD rats (n=8/group) were implanted with subcutaneous osmotic minipumps for infusion of Ang II (300 ng/kg/min) or saline control, with or without EA stimulation. EA groups underwent a 2 Hz EA treatment at the acupoints ST36 or a non-acupoint with the intensity increasing stepwise from 0.5-1-1.5 mA once a day for 30 min. Baroreflex sensitivity index was calculated on the basis of reflex changes in heart rate (HR) related to the arterial pressure (AP) changes induced by phenylephrine or sodium nitroprusside injection, and chemoreflex sensitivity was evaluated by intravenous injections of increasing doses of potassium cyanide (KCN). After 4 weeks of treatment, Ang II significantly increased mean arterial pressure (107±2 and 139±2 mmHg in control vs. Ang II group). Baroreflex sensitivity to AP rises and falls were also impaired in Ang II infusion group (1.3±0.08 and 2.1 ±0.18 bpm/mmHg) compared with those in control group (1.7±0.08 and 2.7±0.06 bpm/mmHg). EA stimulation of ST 36 on Ang II infusion rats significantly improved the impaired baroreflex sensitivity (1.7±0.06 and 2.6±0.1 bpm/mmHg, P < 0.05). In addition, the bradycardic and pressor responses evoked by KCN injections were attenuated in Ang II infusion rats (23±9 bpm and 7±1 mmHg in Ang II group vs. 78±7 bpm and 22±3mmHg in control group, P < 0.05), while EA stimulation improved both chemoreflex responses in AngII rats (84±15 bpm and 32±5 mmHg, P<0.05). In contrast, EA stimulation had no significant effect on control group. These results indicate that EA stimulation improves arterial baroreflex function and chemoreflex sensitivity in conditions of high Ang II.

Download Full-text

Modulation of arterial baroreflex control of heart rate by skin cooling and heating in humans

Journal of Applied Physiology ◽

10.1152/jappl.2000.88.2.393 ◽

2000 ◽

Vol 88 (2) ◽

pp. 393-400 ◽

Cited By ~ 43

Author(s):

Fumio Yamazaki ◽

Ryoko Sone

Keyword(s):

Heart Rate ◽

Thermal Stress ◽

Arterial Pressure ◽

Baroreflex Sensitivity ◽

Whole Body ◽

Arterial Baroreflex ◽

Carotid Baroreflex ◽

Skin Cooling ◽

Neck Pressure ◽

Arterial Baroreflex Sensitivity

The purpose of this study was to examine the effects of skin cooling and heating on the heart rate (HR) control by the arterial baroreflex in humans. The subjects were 15 healthy men who underwent whole body thermal stress (esophageal temperatures, ∼36.8 and ∼37.0°C; mean skin temperatures, ∼26.4 and ∼37.7°C, in skin cooling and heating, respectively) produced by a cool or hot water-perfused suit during supine rest. The overall arterial baroreflex sensitivity in the HR control was calculated from spontaneous changes in beat-to-beat arterial pressure and HR during normothermic control and thermal stress periods. The carotid baroreflex sensitivity was evaluated from the maximum slope of the HR response to changes in carotid distending pressure, calculated as mean arterial pressure minus neck pressure. The overall arterial baroreflex sensitivity at existing arterial pressure increased during cooling (−1.32 ± 0.25 vs. −2.13 ± 0.20 beats ⋅ min− 1 ⋅ mmHg− 1 in the control and cooling periods, respectively, P < 0.05), whereas it did not change significantly during heating (−1.39 ± 0.23 vs. −1.40 ± 0.15 beats ⋅ min− 1 ⋅ mmHg− 1in the control and heating periods, respectively). Neither the cool nor heat loadings altered the carotid baroreflex sensitivity in the HR control. These results suggest that the sensitivity of HR control by the extracarotid (presumably aortic) baroreflex was augumented by whole body skin cooling, whereas the sensitivities of HR control by arterial baroreflex remain unchanged during mild whole body heating in humans.

Download Full-text

158 Importance of arterio-venous fistulas on sympathetic nerve activity and on arterial baroreflex sensitivity in renal transplanted patients

European Heart Journal ◽

10.1016/s0195-668x(03)93703-1 ◽

2003 ◽

Vol 24 (5) ◽

pp. 15

Author(s):

S VELEZROA

Keyword(s):

Sympathetic Nerve ◽

Baroreflex Sensitivity ◽

Sympathetic Nerve Activity ◽

Arterial Baroreflex ◽

Nerve Activity ◽

Arterial Baroreflex Sensitivity

Download Full-text

Impaired baroreflex sensitivity predicts poor short-term outcome in intracerebral haemorrhage – preliminary results

Aktuelle Neurologie ◽

10.1055/s-2007-988079 ◽

2007 ◽

Vol 34 (S 2) ◽

Author(s):

M Sykora ◽

J Diedler ◽

T Steiner

Keyword(s):

Intracerebral Haemorrhage ◽

Baroreflex Sensitivity ◽

Short Term ◽

Term Outcome ◽

Preliminary Results ◽

Short Term Outcome

Download Full-text

Cardiovascular and Valsalva responses during parabolic flight

Journal of Applied Physiology ◽

10.1152/jappl.1998.85.5.1957 ◽

1998 ◽

Vol 85 (5) ◽

pp. 1957-1965 ◽

Cited By ~ 15

Author(s):

Todd T. Schlegel ◽

Edgar W. Benavides ◽

Donald C. Barker ◽

Troy E. Brown ◽

Deborah L. Harm ◽

...

Keyword(s):

Mean Arterial Pressure ◽

Arterial Pressure ◽

Vascular Resistance ◽

Human Subjects ◽

Parabolic Flight ◽

Cardiovascular Responses ◽

Systematic Evaluation ◽

Arterial Baroreflex ◽

Baroreflex Control ◽

Flight Measurements

We investigated the integrated cardiovascular responses of 15 human subjects to the acute gravitational changes (micro- and hypergravity portions) of parabolic flight. Measurements were made with subjects quietly seated and while subjects performed controlled Valsalva maneuvers. During quiet, seated, parabolic flight, mean arterial pressure increased during the transition into microgravity but decreased as microgravity was sustained. The decrease in mean arterial pressure was accompanied by immediate reflexive increases in heart rate but by absent (or later-than-expected) reflexive increases in total vascular resistance. Mean arterial pressure responses in Valsalva phases IIl, III, and IV were accentuated in hypergravity relative to microgravity ( P < 0.01, P < 0.01, and P < 0.05, respectively), but accentuations differed qualitatively and quantitatively from those induced by a supine-to-seated postural change in 1 G. This study is the first systematic evaluation of temporal and Valsalva-related changes in cardiovascular parameters during parabolic flight. Results suggest that arterial baroreflex control of vascular resistance may be modified by alterations of cardiopulmonary, vestibular, and/or other receptor activity.

Download Full-text