Aortic baroreceptors play a predominant role in the regulation of hindlimb vascular resistance in rats

1994 ◽  
Vol 267 (2) ◽  
pp. R476-R480 ◽  
Author(s):  
B. H. Machado ◽  
L. G. Bonagamba ◽  
J. A. Castania ◽  
J. V. Menani
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Carotid Baroreceptor ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Freely Moving ◽  
Vascular Beds ◽  
Aortic Baroreceptors ◽  
Stimulation Of

In previous studies using bilateral carotid occlusion in conscious freely moving rats we suggested that aortic baroreceptors may play a more important role in the regulation of hindlimb than in renal and mesenteric vascular resistances. In the present study we performed electrical stimulation of the aortic baroreceptor nerve and analyzed the changes in mean arterial pressure and in hindlimb, renal, and mesenteric vascular resistances. All the experiments were performed under urethan anesthesia. Unilateral electrical stimulation (3 V, 2 ms, 50 Hz) of the aortic baroreceptor nerve produced a fall in arterial pressure (-27 +/- 3 mmHg) and an important reduction in hindlimb vascular resistance (-43 +/- 5%), with an increase in renal (+3 +/- 14%) and mesenteric (+48 +/- 12%) vascular resistances. Similar changes in arterial pressure as well as in the resistance of the three vascular beds studied were also observed during electrical stimulation of the aortic baroreceptor nerve in rats with bilateral carotid baroreceptor denervation or in rats treated with methylatropine. The data obtained with electrical stimulation indicated that aortic baroreceptors play a more important role in the regulation of blood flow in hindlimb than in renal and mesenteric vascular beds.

Vasoconstrictor and vasodilator sites within anteroventral third ventricle region

1987 ◽  
Vol 253 (6) ◽  
pp. R827-R831 ◽  
Author(s):  
M. L. Mangiapane ◽  
M. J. Brody
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Third Ventricle ◽  
Renal Vascular Resistance ◽  
Preoptic Nucleus ◽  
Median Preoptic Nucleus ◽  
Tungsten Microelectrode ◽  
Renal Vascular ◽  
Stimulation Of

Previous studies have shown that electrical stimulation of the rat anteroventral third ventricle (AV3V) region produces a characteristic pattern of hemodynamic effects, i.e., renal and mesenteric vasoconstriction, and hindquarters vasodilation. In the present study, we localized the vasoconstrictor and vasodilator effects to specific subregions of the AV3V. In urethan-anesthetized rats prepared with arterial catheters and pulsed Doppler flow probes, we assessed the effects of electrical stimulation of four nuclei within AV3V on mean arterial pressure and renal, mesenteric, and hindquarters resistance. These nuclei were the organum vasculosum lamina terminalis (OVLT), ventral nucleus medianus (median preoptic nucleus), anterior (precommissural) nucleus medianus (median preoptic nucleus), and periventricular preoptic nuclei. Stimulation was carried out by use of a tungsten microelectrode. Stimulation of the OVLT consistently provoked stimulus-locked increases in arterial pressure coupled with increases in mesenteric and renal vascular resistance. Ganglionic blockade with chlorisondamine prevented these responses, demonstrating that they were mediated neurogenically. Stimulation of the three remaining nuclei produced decreases in arterial pressure, hindquarters vasodilation, and little change in mesenteric and renal vascular resistance. No changes in heart rate were observed with stimulation of any of the four nuclei. These results suggest that the vasoconstrictor and pressor functions of the AV3V region are localized in or near the OVLT region, whereas the remaining nuclei of the AV3V region mediate vasodilator and depressor responses.

scholarly journals Hemodynamic responses to electrical stimulation of the aortic depressor nerve in awake rats

1999 ◽  
Vol 277 (1) ◽  
pp. R31-R38 ◽  
Author(s):  
Patrícia M. De Paula ◽  
Jaci A. Castania ◽  
Leni G. H. Bonagamba ◽  
Hélio C. Salgado ◽  
Benedito H. Machado
Keyword(s):  
Electrical Stimulation ◽  
Vascular Resistance ◽  
Dependent Manner ◽  
Platinum Electrodes ◽  
Aortic Depressor Nerve ◽  
Afferent Fibers ◽  
Freely Moving ◽  
Vascular Beds ◽  
Mesenteric Vascular Resistance ◽  
Hypotensive Response

Changes in mean arterial pressure (MAP), heart rate (HR), and vascular resistance (hindquarter and mesenteric territories) in response to electrical stimulation (ES) of the aortic depressor nerve (ADN) were evaluated in conscious freely moving rats. Platinum electrodes were implanted into the ADN of all rats studied, and some of these animals were also implanted with miniaturized Doppler probes around the superior mesenteric artery and inferior abdominal aorta (hindquarter). In both groups, the femoral artery and vein were catheterized one day before the experiments. In the first group of rats ( n = 7), the control ES of the ADN in the range from 0.5 to 3.0 V (50 Hz, 10 ms) produced bradycardia and hypotension in an intensity-dependent manner, and treatment with methylatropine (intravenously) blocked the bradycardia but produced no significant changes in the hypotensive response. In a second group ( n = 6), ES of the ADN was performed with the intensity fixed at 3 V and the frequency of the stimuli varying from 10 to 50 Hz. In this group, the hypotensive response was frequency dependent, whereas the bradycardic response was not. In a third group of rats ( n = 6), ES of the ADN (2.5 V) produced hypotension (−35 ± 4 mmHg), minor changes in the mesenteric (+5 ± 14%), and vasodilation in hindquarter (−32 ± 6%) vascular beds. The data show that 1) ES of the ADN produces a fall in pressure, bradycardia, vasodilation in the hindquarter, and no changes in the mesenteric vascular resistance, 2) methylatropine blocked the bradycardia and produced no effect on the hypotensive response to ES of the ADN, and 3) the baroreceptor afferent fibers involved in the hypotensive response to ES of ADN are sensitive to the variation of the frequency of the stimuli, whereas the fibers involved in the bradycardic response are not.

Selective destruction of renal afferent versus efferent nerves in rats

1985 ◽  
Vol 249 (5) ◽  
pp. R634-R637 ◽  
Author(s):  
R. W. Lappe ◽  
R. L. Webb ◽  
M. J. Brody
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Left Kidney ◽  
Hypothalamic Area ◽  
Efferent Nerve ◽  
Selective Destruction ◽  
Dorsal Roots ◽  
Afferent Fibers ◽  
Stimulation Of

Previous anatomic studies demonstrated that afferent projections from the left kidney of the rat passed predominantly through the dorsal roots of spinal segments T10-L1. Selective destruction of renal afferent nerves, without damaging renal efferent nerves, was attempted by severing the dorsal roots carrying the afferent fibers. In anesthetized rats, the dorsal left side of the spinal cord was exposed through a partial laminectomy at vertebral sections T10-L1; and the dorsal roots were carefully isolated and cut. Four to ten days after surgery, arterial pressure and hindquarter vascular resistance were maximally reduced by 14 +/- 2 mmHg and 42 +/- 1%, respectively, during electrical stimulation of renal afferent fibers in sham-operated rats. In rats with selective dorsal rhizotomy no significant changes in arterial pressure or hindquarter vascular resistance were observed after renal afferent nerve stimulation. Renal vasoconstrictor responses to electrical stimulation of the left greater splanchnic nerve or posterior hypothalamic area were not different between sham and rhizotomized rats. These data demonstrate that severing dorsal roots T10-L1 cause a functional afferent denervation of the kidney, without impairing renal efferent nerve function.

Depressed responsiveness of the carotid sinus reflex in conscious newborn animals

1979 ◽  
Vol 237 (1) ◽  
pp. H40-H43 ◽  
Author(s):  
S. F. Vatner ◽  
W. T. Manders
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Peripheral Resistance ◽  
Carotid Baroreceptor ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Baroreceptor Reflexes ◽  
Newborn Animals

The responsiveness of the carotid sinus reflex was evaluated by comparing the effects of bilateral carotid occlusion (BCO) in conscious adult dogs and puppies on measurements of arterial pressure, cardiac output, heart rate, and calculations of total peripheral resistance (TPR). In eight adult dogs, BCO increased mean arterial pressure by 57 +/- 6%, TPR by 48 +/- 5%, and heart rate by 45 +/- 15%. In puppies, BCO induced smaller increases (P less than 0.05) in mean arterial pressure (30 +/- 5%) and TPR (29 +/- 4%), while heart rate did not change. After elimination of opposing vagal and aortic baroreceptor reflexes, the differences in responses to BCO of mean arterial pressure and TPR between adults and newborns were even greater. Thus, the carotid baroreceptor reflex appears to be depressed in the newborn when compared with the fully developed reflex in the normal, conscious adult.

Cerebrovascular effects produced by electrical stimulation of fastigial nucleus

1991 ◽  
Vol 261 (3) ◽  
pp. H707-H713 ◽  
Author(s):  
W. T. Talman ◽  
D. M. Dragon ◽  
D. D. Heistad ◽  
H. Ohta
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Fastigial Nucleus ◽  
Vascular Effect ◽  
Metabolic Mechanism ◽  
Alpha Chloralose ◽  
Stimulation Of

We used the microsphere technique and laser flowmetry to assess cerebral blood flow in 43 anesthetized rats. Cerebral blood flow did not increase significantly when the fastigial nucleus was stimulated 15 min after administration of alpha-chloralose. In animals that received maintenance doses of alpha-chloralose, the modest (50%) increase in cerebral blood flow that did occur returned toward control during stimulation despite a continued stable elevation of arterial pressure. Stimulation of fastigial nucleus 2 h after alpha-chloralose elicited a 20 +/- 3 mmHg increase in arterial pressure; cerebral blood flow increased gradually for 30-60 s after the rise in arterial pressure and reached a peak that was approximately 90% (P less than 0.05) above baseline. The stimuli did not significantly reduce vascular resistance or impair autoregulation. We did not stimulate the fastigial nucleus for more than 2 h after administration of alpha-chloralose because anesthesia was effective for only 2 h. This study demonstrates that stimulation of the fastigial nucleus in rat produces a delayed increase in cerebral blood flow that is blocked by alpha-chloralose anesthesia. The delay in increases of cerebral blood flow suggests that a metabolic mechanism, not a direct neurogenic vascular effect, may account for increases in flow with fastigial stimulation.

Electrical stimulation of the carotid sinus lowers arterial pressure and improves heart rate variability in l-NAME hypertensive conscious rats

2020 ◽  
Vol 43 (10) ◽  
pp. 1057-1067 ◽  
Author(s):  
Gean Domingos-Souza ◽  
Fernanda Machado Santos-Almeida ◽  
César Arruda Meschiari ◽  
Nathanne S. Ferreira ◽  
Camila A. Pereira ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Conscious Rats ◽  
Stimulation Of

Reflex effects of thoracic aorta wall stretch on regional vascular resistance

1978 ◽  
Vol 56 (3) ◽  
pp. 390-394
Author(s):  
Peter M. Szeto ◽  
Franco Lioy
Keyword(s):  
Arterial Pressure ◽  
Thoracic Aorta ◽  
Vascular Resistance ◽  
Carotid Arteries ◽  
Peripheral Resistance ◽  
Adrenergic Blockade ◽  
Vascular Responses ◽  
Regional Vascular Resistance ◽  
Vascular Beds ◽  
Intact Limb

In anesthetized, vagotomized cats with both carotid arteries occluded, a stretch of the walls of the thoracic aorta, performed without obstructing aortic flow, induced a significant reflex increase in arterial pressure (35 ± 2−26 ± 1 mmHg; systolic–diastolic). This pressure increase was accompanied by significant increases in peripheral resistance in the superior mesenteric (+30%), renal (+23%), and external iliac (+23%) vascular beds. The increase in iliac resistance observed in the skinned leg was comparable with that observed in the contralateral intact limb. All these vascular responses were drastically reduced by the administration of phenoxybenzamine. After α-adrenergic blockade no signs of reflex vasodilatation could be detected during aortic stretch in any of the vascular beds examined.

Rebound cardiovascular responses following stimulation of canine vagosympathetic complexes or cardiopulmonary nerves

1985 ◽  
Vol 63 (9) ◽  
pp. 1122-1132 ◽  
Author(s):  
J. A. Armour ◽  
W. C. Randall
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Cardiovascular System ◽  
Cardiovascular Responses ◽  
Systemic Arterial Pressure ◽  
Cardiac Responses ◽  
Stimulation Of

Electrical stimulation of a canine vagosympathetic complex or a cardiopulmonary nerve can elicit a variety of negative chronotropic and inotropic cardiac responses, with or without alterations in systemic arterial pressure. In the period immediately following cessation of such a stimulation "rebound" tachycardia, increased inotropism above control values in one or more regions of the heart, and (or) elevation in systemic arterial pressure can occur. These "rebound" phenomena are abolished by propranolol or ipsilateral chronic sympathectomy. It is proposed that "vagal" poststimulation "rebound" of the canine cardiovascular system is primarily the result of activation of sympathetic neural elements present in the vagosympathetic complexes or cardiopulmonary nerves.

scholarly journals Physiological Sympathetic Activation Reduces Systemic Inflammation: Role of Baroreflex and Chemoreflex

2021 ◽  
Vol 12 ◽  
Author(s):  
Fernanda Brognara ◽  
Jaci Airton Castania ◽  
Alexandre Kanashiro ◽  
Daniel Penteado Martins Dias ◽  
Helio Cesar Salgado
Keyword(s):  
Nervous System ◽  
Arterial Pressure ◽  
Systemic Inflammation ◽  
Inflammatory Responses ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Sympathetic Activation ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Reflex Activation

Baroreflex and chemoreflex act through the autonomic nervous system, which is involved with the neural regulation of inflammation. The present study reports the effects of reflex physiological sympathetic activation in endotoxemic rats using bilateral carotid occlusion (BCO), a physiological approach involving the baroreflex and chemoreflex mechanisms and the influence of the baroreceptors and peripheral chemoreceptors in the cardiovascular and systemic inflammatory responses. After lipopolysaccharide (LPS) administration, the arterial pressure was recorded during 360 min in unanesthetized rats, and serial blood samples were collected to analyze the plasma cytokine levels. BCO elicited the reflex activation of the sympathetic nervous system, providing the following outcomes: (I) increased the power of the low-frequency band in the spectrum of the systolic arterial pressure during the BCO period; (II) reduced the levels of pro-inflammatory cytokines in plasma, including the tumor necrosis factor (TNF) and the interleukin (IL)-1β; (III) increased the plasma levels of anti-inflammatory cytokine IL-10, 90 min after LPS administration. Moreover, selective baroreceptor or chemoreceptor denervation deactivated mechanosensitive and chemical sensors, respectively, and decreased the release of the LPS-induced cytokine but did not alter the BCO modulatory effects. These results show, for the first time, that physiological reflex activation of the sympathetic circuit decreases the inflammatory response in endotoxemic rats and suggest a novel function for the baroreceptors as immunosensors during the systemic inflammation.

Hypothalamic projections of renal afferent nerves in the cat

1980 ◽  
Vol 58 (5) ◽  
pp. 574-576 ◽  
Author(s):  
J. Ciriello ◽  
F. R. Calaresu
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Paraventricular Nucleus ◽  
Fluid Balance ◽  
Lateral Hypothalamus ◽  
Discharge Rate ◽  
Renal Nerves ◽  
Preoptic Nucleus ◽  
Afferent Nerves ◽  
Stimulation Of

In 10 cats anaesthetized with chloralose the electrical activity of spontaneously active hypothalamic units was recorded for changes in discharge rate during electrical stimulation of renal afferent nerves. The discharge rate of 141 single units was altered by stimulation of either the ipsilateral or contralateral renal nerves. Most of the responsive units were located in the regions of lateral preoptic nucleus, lateral hypothalamus, and paraventricular nucleus. These results demonstrate that renal afferent nerves provide information to hypothalamic structures known to be involved in the regulation of arterial pressure and fluid balance.

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