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CNS Neuroscience & Therapeutics Mar 2022To understand the direct impact of bradykinin in autonomic control of circulation through baroreflex afferent pathway.
AIM
To understand the direct impact of bradykinin in autonomic control of circulation through baroreflex afferent pathway.
METHODS
The mean arterial pressure (MAP) was monitored while bradykinin and its agonists were applied via nodose (NG) microinjection, the expression of bradykinin receptors (BRs) in the NG (1 -order) and nucleus tractus solitarius (NTS, 2 -order) were tested in adult male, age-matched female, and ovariectomized rats under physiological and hypertensive conditions. Additionally, bradykinin-induced depolarization was also tested in identified baroreceptor and baroreceptive neurons using whole-cell patch-clamp technique.
RESULTS
Under physiological condition, bradykinin-induced dose- and estrogen-dependent reductions of MAP with lower estimated EC in females. B R agonist mediated more dramatic MAP reduction with long-lasting effect compared with B R activation. These functional observations were consistent with the molecular and immunostaining evidences. However, under hypertensive condition, the MAP reduction was significantly less dramatic in N -Nitro-L-Arginine-methyl ester (L-NAME) induced secondary and spontaneous hypertension rats in males compared with female rats. Electrophysiological data showed that bradykinin-elicited concentration-dependent membrane depolarization with discharges during initial phase in identified myelinated Ah-types baroreceptor neurons, not myelinated A-types; while, higher concentration of bradykinin was required for depolarization of unmyelinated C-types without initial discharges.
CONCLUSION
These datasets have demonstrated for the first time that bradykinin mediates direct activation of baroreflex afferent function to trigger estrogen-dependent depressor response, which is due mainly to the direct activation/neuroexcitation of female-specific myelinated Ah-type baroreceptor neurons leading to a sexual dimorphism in parasympathetic domination of blood pressure regulation via activation of B R/B R expression in baroreflex afferent pathway.
Topics: Animals; Baroreflex; Bradykinin; Estrogens; Female; Hypertension; Male; Neurons; Pressoreceptors; Rats; Rats, Inbred SHR
PubMed: 34964272
DOI: 10.1111/cns.13792 -
Lin Chuang Er Bi Yan Hou Tou Jing Wai... Nov 2021With the continuous updating of head and neck surgery concepts and techniques, more and more head and neck surgeries are developing in the direction of... (Review)
Review
With the continuous updating of head and neck surgery concepts and techniques, more and more head and neck surgeries are developing in the direction of refinement.however, the more complete the surgery, the greater the possibility of subsequent nerve exposure and injury. Even a slight perturbation of the nerve may cause serious complications, such as pressure receptor failure.It is necessary to review the mechanisms and the characteristics of baroreceptor failure syndrome after head and neck tumor surgery.
Topics: Head; Head and Neck Neoplasms; Humans; Neck; Postoperative Complications; Pressoreceptors
PubMed: 34886615
DOI: 10.13201/j.issn.2096-7993.2021.11.020 -
Hypertension (Dallas, Tex. : 1979) Jan 2022
Topics: Baroreflex; Blood Pressure; Pressoreceptors
PubMed: 34878899
DOI: 10.1161/HYPERTENSIONAHA.121.18372 -
Scientific Reports Nov 2021Arterial baroreceptors (BRs) play a vital role in the regulation of the cardiopulmonary system. What is known about how these sensors operate at the subcellular level is...
Arterial baroreceptors (BRs) play a vital role in the regulation of the cardiopulmonary system. What is known about how these sensors operate at the subcellular level is limited, however. Until recently, one afferent axon was considered to be connected to a single baroreceptor (one-sensor theory). However, in the lung, a single airway mechanosensory unit is now known to house many sensors (multiple-sensor theory). Here we tested the hypothesis that multiple-sensor theory also operates in BR units, using both morphological and electrophysiological approaches in rabbit aortic arch (in whole mount) labeled with Na/K-ATPase, as well as myelin basic protein antibodies, and examined microscopically. Sensory structures presented in compact clusters, similar to bunches of grapes. Sensory terminals, like those in the airways, formed leaf-like or knob-like expansions. That is, a single myelinated axon connected with multiple sensors forming a network. We also recorded single-unit activities from aortic baroreceptors in the depressor nerve in anesthetized rabbits and examined the unit response to a bolus intravenous injection of phenylephrine. Unit activity increased progressively as blood pressure (BP) increased. Five of eleven units abruptly changed their discharge pattern to a lower activity level after BP attained a plateau for a minute or two (when BP was maintained at the high level). These findings clearly show that the high discharge baroreceptor deactivates after over-excitation and unit activity falls to a low discharge sensor. In conclusion, our morphological and physiological data support the hypothesis that multiple-sensory theory can be applied to BR units.
Topics: Animals; Antibodies; Aorta; Aorta, Thoracic; Axons; Blood Pressure; Electrophysiology; Lung; Male; Models, Neurological; Myelin Basic Protein; Phenylephrine; Pressoreceptors; Rabbits; Sodium-Potassium-Exchanging ATPase
PubMed: 34848803
DOI: 10.1038/s41598-021-02563-x -
Journal of Clinical Hypertension... Dec 2021We examined in 11 young subjects (age 29.7±3.6 years, mean±SEM) whether carotid baroreceptor stimulation via the neck chamber device may affect central venous pressure...
We examined in 11 young subjects (age 29.7±3.6 years, mean±SEM) whether carotid baroreceptor stimulation via the neck chamber device may affect central venous pressure (CVP), thus potentially involving other reflexogenic areas in the examined responses. Application of progressively greater neck chamber subatmospheric pressures caused a progressive lengthening in RR interval, which reached a peak at the maximal value of negative neck chamber pressure applied. This was accompanied by significant and progressively greater reduction in CVP values when the data were calculated considering the early changes occurring within the first 2 seconds of the stimulus. There was a weak correlation between the early changes in CVP and the RR interval responses when all stimuli were pooled together (r = 0.32, P < .05). The results of the present study suggest that the neck chamber technique employed to assess carotid baroreceptor-heart rate sensitivity can transiently affect via the CVP reduction cardiopulmonary receptors activity, which may participate at the integrated reflex responses.
Topics: Adult; Baroreflex; Blood Pressure; Central Venous Pressure; Heart Rate; Humans; Hypertension; Pressoreceptors
PubMed: 34783435
DOI: 10.1111/jch.14387 -
International Journal of Environmental... Oct 2021This paper presents data from a transcutaneous vagus nerve stimulation experiment that point towards a blunted cardiac baroreceptor sensitivity (cBRS) in young males...
Men Show Reduced Cardiac Baroreceptor Sensitivity during Modestly Painful Electrical Stimulation of the Forearm: Exploratory Results from a Sham-Controlled Crossover Vagus Nerve Stimulation Study.
This paper presents data from a transcutaneous vagus nerve stimulation experiment that point towards a blunted cardiac baroreceptor sensitivity (cBRS) in young males compared to females during electrical stimulation of the forearm and a rhythmic breathing task. Continuous electrocardiography, impedance cardiography and continuous blood-pressure recordings were assessed in a sex-matched cohort of twenty young healthy subjects. Electrical stimulation of the median nerve was conducted by using a threshold-tracking method combined with two rhythmic breathing tasks (0.1 and 0.2 Hz) before, during and after active or sham transcutaneous vagus nerve stimulation. Autonomic and hemodynamic parameters were calculated, and differences were analyzed by using linear mixed models and post hoc F-tests. None of the autonomic and hemodynamic parameters differed between the sham and active conditions. However, compared to females, male participants had an overall lower total cBRS independent of stimulation condition during nerve stimulation (females: 14.96 ± 5.67 ms/mmHg, males: 11.89 ± 3.24 ms/mmHg, = 0.031) and rhythmic breathing at 0.2 Hz (females: 21.49 ± 8.47 ms/mmHg, males: 15.12 ± 5.70 ms/mmHg, = 0.004). Whereas vagus nerve stimulation at the left inner tragus did not affect the efferent vagal control of the heart, we found similar patterns of baroreceptor sensitivity activation over the stimulation period in both sexes, which, however, significantly differed in their magnitude, with females showing an overall higher cBRS.
Topics: Cross-Over Studies; Electric Stimulation; Female; Forearm; Heart Rate; Humans; Male; Pressoreceptors; Vagus Nerve; Vagus Nerve Stimulation
PubMed: 34769711
DOI: 10.3390/ijerph182111193 -
American Journal of Hypertension Dec 2021The present paper will provide an update on the role of sympathetic neural factors in the development and progression of essential hypertension by reviewing data...
The present paper will provide an update on the role of sympathetic neural factors in the development and progression of essential hypertension by reviewing data collected in the past 10 years. This will be done by discussing the results of the published studies in which sympathetic neural function in essential hypertension and related disease has been investigated via sophisticated and highly sensitive techniques, such as microneurographic recording of sympathetic nerve traffic and regional norepinephrine spillover. First, the relevance of the pathophysiological background of the neurogenic alterations will be discussed. It will be then examined the behavior of the sympathetic neural function in specific clinical phenotypes, such as resistant hypertension, pseudoresistant hypertension, and hypertensive states displaying elevated resting heart values. This will be followed by a discussion of the main results of the meta-analytic studies examining the behavior of sympathetic nerve traffic in essential hypertension, obesity, metabolic syndrome, and chronic renal failure. The sympathetic effects of renal denervation and carotid baroreceptor stimulation as well as the possible involvement of sympathetic neural factors in the determination of the so-called "residual risk" of the treated hypertensive patients will be finally discussed.
Topics: Blood Pressure; Humans; Hypertension; Kidney; Norepinephrine; Pressoreceptors; Sympathetic Nervous System
PubMed: 34355740
DOI: 10.1093/ajh/hpab124 -
Acta Pharmacologica Sinica Dec 2021Female-specific subpopulation of myelinated Ah-type baroreceptor neurons (BRNs) in nodose ganglia is the neuroanatomical base of sexual-dimorphic autonomic control of...
Female-specific subpopulation of myelinated Ah-type baroreceptor neurons (BRNs) in nodose ganglia is the neuroanatomical base of sexual-dimorphic autonomic control of blood pressure regulation, and KCa1.1 is a key player in modulating the neuroexcitation in nodose ganglia. In this study we investigated the exact mechanisms underlying KCa1.1-mediated neuroexcitation of myelinated Ah-type BRNs in the presence or absence of estrogen. BRNs were isolated from adult ovary intact (OVI) or ovariectomized (OVX) female rats, and identified electrophysiologically and fluorescently. Action potential (AP) and potassium currents were recorded using whole-cell recording. Consistently, myelinated Ah-type BRNs displayed a characteristic discharge pattern and significantly reduced excitability after OVX with narrowed AP duration and faster repolarization largely due to an upregulated iberiotoxin (IbTX)-sensitive component; the changes in AP waveform and repetitive discharge of Ah-types from OVX female rats were reversed by G1 (a selective agonist for estrogen membrane receptor GPR30, 100 nM) and/or IbTX (100 nM). In addition, the effect of G1 on repetitive discharge could be completely blocked by G15 (a selective antagonist for estrogen membrane receptor GPR30, 3 μM). These data suggest that estrogen deficiency by removing ovaries upregulates KCa1.1 channel protein in Ah-type BRNs, and subsequently increases AP repolarization and blunts neuroexcitation through estrogen membrane receptor signaling. Intriguingly, this upregulated KCa1.1 predicted electrophysiologically was confirmed by increased mean fluorescent intensity that was abolished by estrogen treatment. These electrophysiological findings combined with immunostaining and pharmacological manipulations reveal the crucial role of KCa1.1 in modulation of neuroexcitation especially in female-specific subpopulation of myelinated Ah-type BRNs and extend our current understanding of sexual dimorphism of neurocontrol of BP regulation.
Topics: Animals; Estrogens; Female; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; Neurons; Nodose Ganglion; Ovariectomy; Ovary; Pressoreceptors; Quinolines; Rats, Sprague-Dawley; Rats
PubMed: 34267344
DOI: 10.1038/s41401-021-00722-4 -
Circulation Research Jul 2021
Topics: Blood Pressure; Kidney; Pressoreceptors; Renin
PubMed: 34236885
DOI: 10.1161/CIRCRESAHA.121.319559 -
Neuroscience Bulletin Oct 2021Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2)...
Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2) and transient receptor potential vanilloid subfamily member 1 (TRPV1) have been studied extensively and documented to play important roles. In this study, experiments using aortic arch-aortic nerve preparations isolated from rats revealed that both ASIC2 and TRPV1 are functionally necessary, as blocking either abrogated nearly all pressure-dependent neural discharge. However, whether ASIC2 and TRPV1 work in coordination remained unclear. So we carried out cell-attached patch-clamp recordings in HEK293T cells co-expressing ASIC2 and TRPV1 and found that inhibition of ASIC2 completely blocked stretch-activated currents while inhibition of TRPV1 only partially blocked these currents. Immunofluorescence staining of aortic arch-aortic adventitia from rats showed that ASIC2 and TRPV1 are co-localized in the aortic nerve endings, and co-immunoprecipitation assays confirmed that the two proteins form a compact complex in HEK293T cells and in baroreceptors. Moreover, protein modeling analysis, exogenous co-immunoprecipitation assays, and biotin pull-down assays indicated that ASIC2 and TRPV1 interact directly. In summary, our research suggests that ASIC2 and TRPV1 form a compact complex and function synergistically in the mechano-electrical transduction of arterial baroreceptors. The model of synergism between MSCs may have important biological significance beyond ASIC2 and TRPV1.
Topics: Acid Sensing Ion Channels; Animals; HEK293 Cells; Humans; Pressoreceptors; Rats; TRPV Cation Channels
PubMed: 34215968
DOI: 10.1007/s12264-021-00737-1