Acute effects of sublingual nitroglycerin on cardiovagal and sympathetic baroreflex sensitivity

2021 ◽  
Author(s):  
Takuto Hamaoka ◽  
Cheryl Blaha ◽  
J. Carter Luck ◽  
Urs A. Leuenberger ◽  
Lawrence I. Sinoway ◽  
...  
Keyword(s):  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Sublingual Administration ◽  
Acute Effects ◽  
Clinical Dose ◽  
Acute Responses ◽  
Coronary Syndromes ◽  
The Relationship ◽  
Beat Heart

The effects of nitroglycerin (glyceryl trinitrate, GTN) on baroreflex sensitivity (BRS) are incompletely understood. Moreover, there are no reports evaluating the acute responses in both the sympathetic BRS (SBRS) and the cardiovagal BRS (CBRS) to the administration of sublingual GTN. We hypothesized that sublingual GTN modulates both CBRS and SBRS. In 10 healthy subjects, beat-to-beat heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded before and for 10 min after sublingual administration of GTN 0.4 mg. SBRS was evaluated from the relationship between spontaneous variations in diastolic BP and MSNA. CBRS was assessed with the sequence technique. These variables were assessed during baseline, during min 3rd - 6th (Post A) and 7th -10th min (Post B) after GTN administration. Two min after GTN administration, MSNA increased significantly and remained significantly elevated during recording. Compared to baseline, CBRS decreased significantly (Post A: 12.9 ± 1.6 to 7.1 ± 1.0 ms/mmHg, P < 0.05), while SBRS increased significantly (Post A: 0.8 ± 0.2 to 1.5 ± 0.2 units･beat-1･mmHg-1, P < 0.05) with an upward shift of the operating point. There were no differences in these variables between Post A and B. A clinical dose of GTN increased MSNA rapidly through effects on both CBRS and SBRS. These effects should be kept in mind when nitrates are used to clinically treat chest pain and acute coronary syndromes and used as vasodilators in experimental settings.

scholarly journals Sympathetic baroreflex sensitivity is inversely related to vascular transduction in men but not women

2019 ◽  
Vol 317 (6) ◽  
pp. H1203-H1209 ◽  
Author(s):  
Sarah L. Hissen ◽  
Vaughan G. Macefield ◽  
Rachael Brown ◽  
Chloe E. Taylor
Keyword(s):  
Blood Pressure ◽  
Sympathetic Nerve ◽  
Inverse Relationship ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Diastolic Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
The Relationship ◽  
Compensatory Interactions

Sympathetic baroreflex sensitivity (BRS) is a measure of how effectively the baroreflex buffers beat-to-beat changes in blood pressure through the modulation of muscle sympathetic nerve activity (MSNA). However, current methods of assessment do not take into account the transduction of sympathetic nerve activity at the level of the vasculature, which is known to vary between individuals. In this study we tested the hypothesis that there is an inverse relationship between sympathetic BRS and vascular transduction. In 38 (18 men) healthy adults, continuous measurements of blood pressure, MSNA and superficial femoral artery diameter and blood flow (Doppler ultrasound) were recorded during 10 min of rest. Spontaneous sympathetic BRS was quantified as the relationship between diastolic pressure and MSNA burst incidence. Vascular transduction was quantified by plotting the changes in leg vascular conductance for 10 cardiac cycles following each burst of MSNA, and taking the nadir. In men, sympathetic BRS was inversely related to vascular transduction ( r = −0.49; P = 0.04). However, this relationship was not present in women ( r = −0.17; P = 0.47). To conclude, an interaction exists between sympathetic BRS and vascular transduction in healthy men, such that men with high sympathetic BRS have low vascular transduction and vice versa. This may be to ensure that blood pressure is regulated effectively, although further research is needed to explore what mechanisms are involved and examine why this relationship was not apparent in women. NEW & NOTEWORTHY Evidence suggests that compensatory interactions exist between factors involved in cardiovascular control. This study was the first to demonstrate an inverse relationship between sympathetic BRS and beat-to-beat vascular transduction. Those with low sympathetic BRS had high vascular transduction and vice versa. However, this interaction was present in young men but not women.

Acute effects of electronic cigarettes on arterial pressure and peripheral sympathetic activity in young non-smokers

2020 ◽  
Author(s):  
Joshua Eric Gonzalez ◽  
William Harold Cooke
Keyword(s):  
Arterial Pressure ◽  
Health Risks ◽  
Sympathetic Activity ◽  
Sympathetic Nerve Activity ◽  
Electronic Cigarettes ◽  
Muscle Sympathetic Nerve Activity ◽  
Crossover Design ◽  
Acute Effects ◽  
Nerve Activity ◽  
Peripheral Sympathetic Activity

E-cigarettes like the JUUL are marketed as an alternative to smoking for those who want to decrease the health risks of tobacco. Tobacco cigarettes increase heart rate (HR) and arterial pressure (AP), while reducing muscle sympathetic nerve activity (MSNA) through sympathetic baroreflex inhibition. The acute effects of e-cigarettes on AP and MSNA have not been reported: our purpose was to clarify this issue. Using a randomized crossover design, participants inhaled on a JUUL containing nicotine (59 mg/ml) and a similar placebo e-cigarette (0 mg/ml). Experiments were separated by ~1 month. We recorded baseline ECG, AP (n=15), and MSNA (n=10). Subjects rested for 10 min, (BASE) and then inhaled once every 30 s on an e-cigarette that contained nicotine or placebo (VAPE) for 10 min followed by a 10-min recovery (REC). Data were expressed as Δmeans±SE from BASE. HR increased in the nicotine condition during VAPE and returned to BASE values in REC (5.0±1.3 nicotine vs 0.1±0.8 b/min placebo, during VAPE P<.01). AP increased in the nicotine condition during VAPE and remained elevated during REC. (6.5±1.6 nicotine vs 2.6±1 mmHg placebo, during VAPE and 4.6.0±1.7 nicotine vs 1.4±1.4 mmHg placebo during REC; p<.05). MSNA decreased from BASE to VAPE and did not restore during REC (-7.1±1.6 nicotine vs 2.6±2 bursts/min placebo during VAPE and -5.8±1.7 nicotine vs 0.5±1.4 placebo during REC; p<.05). Our results show that acute e-cigarette usage increases mean arterial pressure leading to a baroreflex mediated inhibition of MSNA.

Does infusion of ANG II increase muscle sympathetic nerve activity in patients with primary aldosteronism?

2008 ◽  
Vol 294 (6) ◽  
pp. R1873-R1879 ◽  
Author(s):  
Toshiyoshi Matsukawa ◽  
Takenori Miyamoto
Keyword(s):  
Primary Aldosteronism ◽  
Sympathetic Nerve ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Pressor Response ◽  
Muscle Sympathetic Nerve Activity ◽  
Venous Pressure ◽  
Ang Ii ◽  
Nerve Activity ◽  
Unilateral Adrenalectomy

Patients with primary aldosteronism (PA) were shown to have suppressed muscle sympathetic nerve activity (MSNA) in our previous study. Although baroreflex inhibition probably accounts in part for this reduced MSNA in PA, we hypothesized that the lowered activity of the renin-angiotensin system in PA may also contribute to the suppressed SNA. We recorded MSNA in 9 PA and 16 age-matched normotensive controls (NC). In PA, the resting mean blood pressure (MBP) and serum sodium concentrations were increased, and MSNA was reduced. We examined the effects of infusion of a high physiological dose of ANG II (5.0 ng·kg−1·min−1) on MSNA in 6 of 9 PA and 9 of 16 NC. Infusion of ANG II caused a greater pressor response in PA than NC, but, in spite of the greater increase in pressure, MSNA increased in PA, whereas it decreased in NC. Simultaneous infusion of nitroprusside and ANG II, to maintain central venous pressure at the baseline level and reduce the elevation in MBP induced by ANG II, caused significantly greater increases in MSNA in PA than in NC. Baroreflex sensitivity of heart rate, estimated during phenylephrine infusions, was reduced in PA, but baroreflex sensitivity of MSNA was unchanged in PA compared with NC. All the abnormalities in PA were eliminated following unilateral adrenalectomy. In conclusion, the suppressed SNA in PA depends in part on the low level of ANG II in these patients.

scholarly journals Sympathetic function during whole body cooling is altered in hypertensive adults

2017 ◽  
Vol 123 (6) ◽  
pp. 1617-1624 ◽  
Author(s):  
Jody L. Greaney ◽  
W. Larry Kenney ◽  
Lacy M. Alexander
Keyword(s):  
Blood Pressure ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Whole Body ◽  
Mean Skin Temperature ◽  
Nerve Activity ◽  
Sympathetic Function ◽  
Body Cooling ◽  
Whole Body Cooling

During moderate cold exposure, cardiovascular-related morbidity and mortality increase disproportionately in hypertensive adults (HTN); however, the mechanisms underlying this association are not well defined. We hypothesized that whole body cold stress would evoke exaggerated increases in blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in HTN compared with normotensive adults (NTN) and that sympathetic baroreflex function would be altered during cooling in HTN. MSNA (peroneal microneurography) and beat-to-beat BP (Finometer) were measured continuously in 10 NTN (6 men/4 women; age 53 ± 3 yr; resting BP 125 ± 3/79 ± 1 mmHg) and 13 HTN (7 men/6 women; age 58 ± 2 yr; resting BP 146 ± 5/88 ± 2 mmHg) during whole body cooling-induced reductions in mean skin temperature (Tsk; water-perfused suit) from 34.0 to 30.5°C. During cooling, the increase in mean arterial pressure was greater in HTN (NTN: Δ6 ± 2 vs. HTN: Δ11 ± 1 mmHg; P = 0.02) and accompanied by exaggerated increases in MSNA (NTN: Δ8 ± 3 vs. HTN: Δ20 ± 3 bursts/100 heart beats; P < 0.01). The slope of the relation between MSNA and diastolic BP did not change during cooling in NTN (Tsk 34.0°C: −4.4 ± 0.8 vs. Tsk 30.5°C: −5.0 ± 0.3 bursts·100 heart beats−1·mmHg−1; P = 0.47) but increased in HTN (Tsk 34.0°C: −3.6 ± 0.4 vs. Tsk 30.5°C: −5.4 ± 0.4 bursts·100 heart beats)−1·mmHg−1; P = 0.02). These findings demonstrate that the cooling-induced increases in BP and MSNA are exaggerated in HTN. Furthermore, during cooling, sympathetic baroreflex sensitivity increases in HTN, but not NTN, presumably to allow for baroreflex-mediated buffering of excessive cooling-induced increases in BP. Collectively, these findings suggest that sympathetic function is altered during whole body cooling in hypertension. NEW & NOTEWORTHY These novel findings demonstrate that whole body cooling-induced reductions in mean skin temperature elicited greater increases in blood pressure and muscle sympathetic nerve activity in hypertensive adults. In addition, during moderate cold exposure, sympathetic baroreflex sensitivity increased in hypertensive, but not normotensive, adults.

scholarly journals Cardiac and Sympathetic Baroreflexes Remain Functional During Local Anesthesia With Vasoconstrictor-free Mepivacaine in Humans

2020 ◽  
Author(s):  
Chiaki Furutani ◽  
Kazushige Isono ◽  
Hironao Asahina ◽  
Yudai Higuchi ◽  
Kota Miyahara ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Local Anesthesia ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Mandibular Foramen ◽  
Pressor Responses ◽  
Operating Points

Abstract Local anesthesia with vasoconstrictor-free mepivacaine is known to not evoke pressor responses. However, it is unknown whether baroreflex function and blood pressure (BP) fluctuations are preserved by using mepivacaine. We tested the hypothesis that mepivacaine reduces baroreflex sensitivity (BRS) without changing its operating point. Beat-by-beat BP, heart rate (HR), and muscle sympathetic nerve activity (MSNA) were measured upon injection of either saline (CNT) or 3% mepivacaine (MPV) in the apical regions of the premolars and around the mandibular foramen in 10 healthy young men [23±5 (SD) years]. Cardiac and sympathetic BRSs were assessed by bolus injections of sodium nitroprusside followed by phenylephrine HCl, and then determined from the slopes of regression lines between systolic BP and HR and between diastolic BP and MSNA, respectively. HR was significantly higher in MPV than CNT (P<0.05), while there were no significant differences in MSNA, the operating points, or BP fluctuations between MPV and CNT (all P>0.05). Moreover, neither cardiac nor sympathetic BRS in CNT were altered by MPV (−0.71±0.13 vs. −0.78±0.33 beats·min−1·mmHg−1, P=0.41; −0.98±0.35 vs. −0.92±0.16 units･beat−1･ mmHg−1, P=0.73). Cardiac and sympathetic baroreflex functions were preserved and BP fluctuation may be well maintained under local anesthesia using vasoconstrictor-free 3% mepivacaine.

scholarly journals Within-breath sympathetic baroreflex sensitivity is modulated by lung volume but unaffected by acute intermittent hypercapnic hypoxia in men

2020 ◽  
Vol 319 (1) ◽  
pp. H213-H221
Author(s):  
Massimo Nardone ◽  
André L. Teixeira ◽  
Anthony V. Incognito ◽  
Tyler D. Vermeulen ◽  
Brooke M. Shafer ◽  
...  
Keyword(s):  
Lung Volume ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Lung Volumes ◽  
Hypercapnic Hypoxia ◽  
Spontaneously Breathing ◽  
Resting Muscle ◽  
Insight Into

In resting spontaneously breathing men, the present study observed that sympathetic baroreflex sensitivity (BRS) was higher during low versus high lung volumes but not different between inspiration and expiration. High- but not low-lung volume BRS was negatively associated with resting muscle sympathetic nerve activity (MSNA). Acute intermittent hypercapnic hypoxia increased resting MSNA and diastolic blood pressure, without altering within-breath BRS. These findings provide novel insight into mechanisms controlling within-breath modulation of MSNA in humans.

scholarly journals Device-guided slow breathing reduces blood pressure and sympathetic activity in young normotensive individuals of both sexes

2019 ◽  
Vol 127 (4) ◽  
pp. 1042-1049 ◽  
Author(s):  
Tessa E. Adler ◽  
Yasmine Coovadia ◽  
Domenica Cirone ◽  
Maha L. Khemakhem ◽  
Charlotte W. Usselman
Keyword(s):  
Blood Pressure ◽  
Body Mass Index ◽  
Body Mass ◽  
Sympathetic Nerve ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Main Effect ◽  
Slow Breathing

Slow breathing (SLOWB) is recommended for use as an adjuvant treatment for hypertension. However, the extent to which blood pressure (BP) responses to SLOWB differ between men and women are not well-established. Therefore, we tested the hypothesis that an acute bout of SLOWB would induce larger decreases in BP in males than in females, given that males typically have higher resting BP. We also examined autonomic contributors to reduced BP during SLOWB; that is, muscle sympathetic nerve activity and spontaneous cardiovagal (sequence method) and vascular sympathetic baroreflex sensitivity. We tested normotensive females ( n = 10, age: 22 ± 2 y, body mass index: 22 ± 2 kg/m2) and males ( n = 12, age: 23 ± 3 y, body mass index: 26 ± 4 kg/m2). Subjects were tested at baseline and during the last 5 min of a 15-min RESPeRATE-guided SLOWB session. Overall, SLOWB reduced systolic BP by 3.2 ± 0.8 mmHg (main effect, P < 0.01). Females had lower systolic BP (main effect, P = 0.02); we observed no interaction between sex and SLOWB. SLOWB also reduced muscle sympathetic nerve activity burst incidence by −5.0 ± 1.4 bursts/100 heartbeats (main effect, P < 0.01). Although females tended to have lower burst incidence (main effect, P = 0.1), there was no interaction between sex and SLOWB. Cardiovagal baroreflex sensitivity improved during SLOWB (21.0 vs. 36.0 ms/mmHg, P = 0.03) with no effect of sex. Despite lower overall BP in females, our data support a lack of basement effect on SLOWB-induced reductions in BP, as SLOWB was equally effective in reducing BP in males and females. Our findings support the efficacy of the RESPeRATE device for reducing BP in both sexes, even in young, normotensive individuals. NEW & NOTEWORTHY We provide support for the effectiveness of device-guided slow breathing for blood pressure reduction in young normotensive women and men. Despite having lower baseline blood pressure and sympathetic nerve activity, women experienced equivalent reductions in both measures in response to RESPeRATE-guided slow breathing as men. Thus, slow breathing appears to be effective in young healthy normotensive individuals of both sexes and may be an ideal preventative therapy against future hypertension.

scholarly journals Vestibulosympathetic reflex during the early follicular and midluteal phases of the menstrual cycle

2008 ◽  
Vol 294 (6) ◽  
pp. E1046-E1050 ◽  
Author(s):  
Johnathan E. Lawrence ◽  
Chester A. Ray ◽  
Jason R. Carter
Keyword(s):  
Heart Rate ◽  
Menstrual Cycle ◽  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Vestibulosympathetic Reflex ◽  
Autonomic Reflexes ◽  
Cardiovascular Center ◽  
Healthy Females

Evidence suggests that both the arterial baroreflex and vestibulosympathetic reflex contribute to blood pressure regulation, and both autonomic reflexes integrate centrally in the medulla cardiovascular center. A previous report indicated increased sympathetic baroreflex sensitivity during the midluteal (ML) phase of the menstrual cycle compared with the early follicular (EF) phase. On the basis of this finding, we hypothesize an augmented vestibulosympathetic reflex during the ML phase of the menstrual cycle. Muscle sympathetic nerve activity (MSNA), mean arterial pressure (MAP), and heart rate responses to head-down rotation (HDR) were measured in 10 healthy females during the EF and ML phases of the menstrual cycle. Plasma estradiol (Δ72 ± 13 pg/ml, P < 0.01) and progesterone (Δ8 ± 2 ng/ml, P < 0.01) were significantly greater during the ML phase compared with the EF phase. The menstrual cycle did not alter resting MSNA, MAP, and heart rate (EF: 13 ± 3 bursts/min, 80 ± 2 mmHg, 65 ± 2 beats/min vs. ML: 14 ± 3 bursts/min, 81 ± 3 mmHg, 64 ± 3 beats/min). During the EF phase, HDR increased MSNA (Δ3 ± 1 bursts/min, P < 0.02) but did not change MAP or heart rate (Δ0 ± 1 mmHg and Δ1 ± 1 beats/min). During the ML phase, HDR increased both MSNA and MAP (Δ4 ± 1 bursts/min and Δ3 ± 1 mmHg, P < 0.04) with no change in heart rate (Δ0 ± 1 beats/min). MSNA and heart rate responses to HDR were not different between the EF and ML phases, but MAP responses to HDR were augmented during the ML phase ( P < 0.03). Our results demonstrate that the menstrual cycle does not influence the vestibulosympathetic reflex but appears to alter MAP responses to HDR during the ML phase.

Pressor responses to isometric biting are evoked by somatosensory receptors in periodontal tissue in humans

2009 ◽  
Vol 107 (2) ◽  
pp. 531-539 ◽  
Author(s):  
Yoshiyuki Okada ◽  
Yoshi-ichiro Kamijo ◽  
Kazunobu Okazaki ◽  
Shizue Masuki ◽  
Masaki Goto ◽  
...  
Keyword(s):  
Baroreflex Sensitivity ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Voluntary Contraction ◽  
Periodontal Tissue ◽  
Arterial Baroreflex ◽  
Vascular Conductance ◽  
Nerve Activity ◽  
Pressor Responses ◽  
Cutaneous Vascular Conductance

Jaw muscle contraction, such as mastication and biting (BT), is known to evoke pressor responses. We examined whether the responses were evoked by somatosensory receptors in periodontal tissue and, moreover, whether they were accompanied by altered arterial baroreflex sensitivity. In the first experiment, we measured mean arterial pressure, heart rate, and muscle sympathetic nerve activity from the peroneal nerve during 2-min isometric BT at 50% maximal voluntary contraction before [control (CNT)] and after pharmacological alveolar nerve block (BLK) in eight young men, while monitoring finger cutaneous vascular conductance, gingival vascular conductance (GVC), surface electromyogram of masseter muscle, and BT force. In the second experiment, cardiac and sympathetic baroreflex sensitivities were successfully determined in eight and five of the subjects, respectively, by the modified Oxford method during 5-min BT at 30% maximal voluntary contraction and also during resting without BT in CNT and BLK, respectively. In the first experiment, although BT in CNT and BLK significantly increased mean arterial pressure, heart rate, and total muscle sympathetic nerve activity (burst amplitude × burst incidence), and decreased finger cutaneous vascular conductance and GVC ( P < 0.05), all changes except GVC were markedly attenuated in BLK ( P < 0.05). There were no significant differences in integrated electromyogram and BT force among any trials. In the second experiment, although BT in CNT significantly decreased cardiac and sympathetic baroreflex sensitivities (both, P < 0.05), these changes disappeared in BLK. These results suggest that somatosensory receptors in periodontal tissue were involved in pressor responses to isometric BT, which was accompanied by decreased arterial baroreflex sensitivity.

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