| 1. |
- Peinado, A. B., et al.
(författare)
-
Neural control of blood pressure in women: differences according to age
- 2017
-
Ingår i: Clinical Autonomic Research. - : Springer Science and Business Media LLC. - 0959-9851 .- 1619-1560. ; 27:3, s. 157-165
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose The blood pressure "error signal'' represents the difference between an individual's mean diastolic blood pressure and the diastolic blood pressure at which 50% of cardiac cycles are associated with a muscle sympathetic nerve activity burst (the "T50''). In this study we evaluated whether T50 and the error signal related to the extent of change in blood pressure during autonomic blockade in young and older women, to study potential differences in sympathetic neural mechanisms regulating blood pressure before and after menopause. Methods We measured muscle sympathetic nerve activity and blood pressure in 12 premenopausal (25 +/- 1 years) and 12 postmenopausal women (61 +/- 2 years) before and during complete autonomic blockade with trimethaphan camsylate. Results At baseline, young women had a negative error signal (-8 +/- 1 versus 2 +/- 1 mmHg, p < 0.001; respectively) and lower muscle sympathetic nerve activity (15 +/- 1 versus 33 +/- 3 bursts/min, p < 0.001; respectively) than older women. The change in diastolic blood pressure after autonomic blockade was associated with baseline T50 in older women (r = -0.725, p = 0.008) but not in young women (r = -0.337, p = 0.29). Women with the most negative error signal had the lowest muscle sympathetic nerve activity in both groups (young: r = 0.886, p < 0.001; older: r = 0.870, p < 0.001). Conclusions Our results suggest that there are differences in baroreflex control of muscle sympathetic nerve activity between young and older women, using the T50 and error signal analysis. This approach provides further information on autonomic control of blood pressure in women.
|
|
| 2. |
- Barnes, J. N., et al.
(författare)
-
Aging enhances autonomic support of blood pressure in women
- 2014
-
Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 63:2, s. 303-308
-
Tidskriftsartikel (refereegranskat)abstract
- The autonomic nervous system plays a central role in both acute and chronic blood pressure regulation in humans. The activity of the sympathetic branch of the autonomic nervous system is positively associated with peripheral resistance, an important determinant of mean arterial pressure in men. In contrast, there is no association between sympathetic nerve activity and peripheral resistance in women before menopause, yet a positive association after menopause. We hypothesized that autonomic support of blood pressure is higher after menopause in women. We examined the effect of ganglionic blockade on arterial blood pressure and how this relates to baseline muscle sympathetic nerve activity in 12 young (25±1 years) and 12 older postmenopausal (61±2 years) women. The women were studied before and during autonomic blockade using trimethaphan camsylate. At baseline, muscle sympathetic nerve activity burst frequency and burst incidence were higher in the older women (33±3 versus 15±1 bursts/min; 57±5 versus 25±2 bursts/100 heartbeats, respectively; P<0.05). Muscle sympathetic nerve activity bursts were abolished by trimethaphan within minutes. Older women had a greater decrease in mean arterial pressure (-29±2 versus-9±2 mm Hg; P<0.01) and total peripheral resistance (-10±1 versus-5±1 mm Hg/L per minute; P<0.01) during trimethaphan. Baseline muscle sympathetic nerve activity was associated with the decrease in mean arterial pressure during trimethaphan (r=-0.74; P<0.05). In summary, our results suggest that autonomic support of blood pressure is greater in older women compared with young women and that elevated sympathetic nerve activity in older women contributes importantly to the increased incidence of hypertension after menopause. © 2013 American Heart Association, Inc.
|
|
| 3. |
|
|
| 4. |
- Dutoit, Andrea P, et al.
(författare)
-
Cardiac baroreflex sensitivity is not correlated to sympathetic baroreflex sensitivity within healthy, young humans.
- 2010
-
Ingår i: Hypertension. - 1524-4563. ; 56:6, s. 1118-1123
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate the relationship between the cardiac and sympathetic baroreflex sensitivities within healthy, young humans. The sensitivities of the cardiac and sympathetic baroreflexes were compared in 53 normotensive individuals (28 men and 25 women; age: 24.0 ± 0.9 years; body mass index: 24.0 ± 0.3 cm/kg², mean ± SEM). Heart rate, arterial blood pressure, and peroneal muscle sympathetic nerve activity were recorded under resting conditions (heart rate: 58 ± 1 bpm; systolic blood pressure: 126 ± 2 mm Hg; diastolic blood pressure: 72 ± 1 mm Hg; mean arterial blood pressure: 89 ± 1 mm Hg; muscle sympathetic nerve activity: 18 ± 1 bursts per min) and during rapid changes in blood pressure induced by sequential boluses of nitroprusside and phenylephrine. Cardiac and sympathetic baroreflex sensitivities were analyzed using the slopes of the linear portions of the muscle sympathetic nerve activity-diastolic blood pressure and R-R interval-systolic blood pressure relationships, respectively. When individual cardiac baroreflex sensitivity was compared with sympathetic baroreflex sensitivity, no correlation (R-R interval: r = -0.13; heart rate: r = 0.21) was observed when studied as a group. Analysis by sex unveiled a correlation in women between the cardiac and sympathetic baroreflex sensitivities (R-R interval: r = -0.54; P = 0.01; no correlation with hazard ratio: r = 0.29). No relationship was found in men (R-R interval: r = 0.17; heart rate: r = 0.12). These results indicate that, although both cardiac and sympathetic efferents function in baroreflex control of arterial pressure, there is no correlation in their sensitivities within healthy normotensive humans. However, sex-stratified data indicate that sex-based differential correlations might exist.
|
|
| 5. |
|
|
| 6. |
- Hart, Emma C, et al.
(författare)
-
Baroreflex control of muscle sympathetic nerve activity: a nonpharmacological measure of baroreflex sensitivity.
- 2010
-
Ingår i: American journal of physiology. Heart and circulatory physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 298:3, s. H816-22
-
Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of baroreflex control of sympathetic nerve activity (SNA) represents the responsiveness of SNA to changes in blood pressure. In a slightly different analysis, the baroreflex threshold measures the probability of whether a sympathetic burst will occur at a given diastolic blood pressure. We hypothesized that baroreflex threshold analysis could be used to estimate the sensitivity of the sympathetic baroreflex measured by the pharmacological modified Oxford test. We compared four measures of sympathetic baroreflex sensitivity in 25 young healthy participants: the "gold standard" modified Oxford analysis (nitroprusside and phenylephrine), nonbinned spontaneous baroreflex analysis, binned spontaneous baroreflex analysis, and threshold analysis. The latter three were performed during a quiet baseline period before pharmacological intervention. The modified Oxford baroreflex sensitivity was significantly related to the threshold slope (r = 0.71, P < 0.05) but not to the binned (1 mmHg bins) and the nonbinned spontaneous baroreflex sensitivity (r = 0.22 and 0.36, respectively, P > 0.05), which included burst area. The threshold analysis was also performed during the modified Oxford manipulation. Interestingly, we found that the threshold analysis results were not altered by the vasoactive drugs infused for the modified Oxford. We conclude that the noninvasive threshold analysis technique can be used as an indicator of muscle SNA baroreflex sensitivity as assessed by the modified Oxford technique. Furthermore, the modified Oxford method does not appear to alter the properties of the baroreflex.
|
|
| 7. |
- Hart, Emma C, et al.
(författare)
-
Hysteresis in the sympathetic baroreflex: role of baseline nerve activity.
- 2011
-
Ingår i: The Journal of physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 589:Pt 13, s. 3395-404
-
Tidskriftsartikel (refereegranskat)abstract
- Sympathetic baroreflex sensitivity (BRS) is greater during decreasing compared to increasing diastolic blood pressure (DBP) in young men and women. In older men and women there is no difference in sympathetic BRS to increasing and decreasing DBP. We investigated whether the sensitivity of the central nervous system to increasing and decreasing DBP is dependent upon baseline muscle sympathetic nerve activity (MSNA). We hypothesised that the difference in sympathetic BRS between falling and rising segments of DBP would be positively related to baseline MSNA in 30 young men, 21 young women, 14 older men and 14 postmenopausal women. MSNA was measured using peroneal microneurography and BRS was measured using the spontaneous baroreflex threshold technique. On average, sympathetic BRS was greater during decreasing compared to increasing DBP in young men (P <0.05) and women (P <0.05). In older men and women, mean sympathetic BRS was similar in response to increasing and decreasing DBP. The difference (delta) between the falling and rising BRS correlated with baseline MSNA in young (r =0.58, P <0.05) and older men (r =0.66, P <0.05) and postmenopausal women (r =0.74, P <0.05). Thus, all men, and older women, with higher BRS to falling DBP had lower baseline MSNA. This relationship was not observed in young women (r =0.14, P >0.05). In summary, baseline MSNA plays a role in determining sympathetic BRS to falling and rising DBP in young and older men and postmenopausal women, but not in young women. This relationship is consistent with a decreased potential for sympathoexcitation in people with higher resting MSNA. Furthermore, the lack of relationship in young women suggests important contributions of sex hormones to differential responses of MSNA to falling and rising pressures.
|
|
| 8. |
|
|
| 9. |
- Krogstad, Anne-Lene, 1956, et al.
(författare)
-
Evaluation of objective methods to diagnose palmar hyperhidrosis and monitor effects of botulinum toxin treatment.
- 2004
-
Ingår i: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. - : Elsevier BV. - 1388-2457. ; 115:8, s. 1909-16
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate (1) if laboratory tests may be a useful complement in diagnosing palmar hyperhidrosis and (2) if such tests can be used in the follow up examination of treatment effects. METHODS: Repeated measurements of evaporation and conductance were made in glabrous skin on hands and compared with subjective estimates of the degree of sweating in 20 control subjects and 20 patients with a history of palmar hyperhidrosis. In addition, 17 patients were monitored for up to 6 months after treatment of the hands with botulinum toxin A. RESULTS: Before treatment, evaporation in the palms was higher in the patients than in the control subjects but skin conductance did not differ between the groups. After treatment both evaporation and skin conductance decreased markedly in the patients and then slowly returned towards pretreatment values. CONCLUSIONS: Measurements of evaporation, but not skin conductance, may be a useful objective adjunct when diagnosing palmar hyperhidrosis. Both methods can, however, be used to monitor intraindividual changes of sweating over time.
|
|
| 10. |
|
|
