Young non-Hispanic Black adults have reduced microvascular endothelial function compared with non-Hispanic White counterparts, but the mechanisms are not fully elucidated. The purpose of this study was to investigate the effect of endothelin-1 A receptor (ETAR) and superoxide on cutaneous microvascular function in young non-Hispanic Black (n=10) and White (n=10) adults. Participants were instrumented with four intradermal microdialysis fibers: 1) lactated Ringer's (control), 2) 500 nM BQ-123 (ETAR antagonist), 3) 10 μM tempol (superoxide dismutase mimetic), and 4) BQ-123 + tempol. Skin blood flow was assessed via laser-Doppler flowmetry (LDF), and each site underwent rapid local heating from 33°C to 39°C. At the plateau of local heating, 20 mM L-NAME [nitric oxide (NO) synthase inhibitor] was infused to quantify NO-dependent vasodilation. Data are mean ± standard deviation. NO-dependent vasodilation was decreased in non-Hispanic Black compared with non-Hispanic White young adults (p < 0.01). NO-dependent vasodilation was increased at BQ-123 sites (73 ± 10% NO) and at BQ-123 + tempol sites (71 ± 10 %NO) in non-Hispanic Black young adults compared with control (53 ± 13 %NO, p = 0.01). Tempol alone had no effect on NO-dependent vasodilation in non-Hispanic Black young adults (63 ± 14 %NO, p = 0.18). NO-dependent vasodilation at BQ-123 sites was not statistically different between non-Hispanic Black and White (80 ± 7 %NO) young adults (p = 0.15). ETAR contribute to reduced NO-dependent vasodilation in non-Hispanic Black young adults independent of superoxide, suggesting a greater effect on NO synthesis rather than NO scavenging via superoxide.
The effect of a six-week strenuous exercise training programme (modified Bruce protocol, treadmill, three times per week) on resting and exercising blood pressure, heart rate, plasma catecholamines, chromogranin A, renin activity and aldosterone levels was investigated in 15 patients with mild hypertension. An identical exercise test was conducted at baseline and study close (six weeks). At follow-up, seven to ten days after study close, patients completed an exercise test of equivalent intensity to that at baseline, achieving comparable heart rate levels at maximal exercise. On each occasion, blood pressure, heart rate and hormonal variables were measured at rest (supine), maximal exercise and ten minutes after stopping exercise. Resting and exercising blood pressure and heart rate were reduced by the six-week exercise regimen. There was a trend, although not statistically significant, for resting plasma noradrenaline levels to be lower at study close. The reduction in blood pressure and heart rate at maximal exercise was associated with a significant attenuation of the plasma renin response to exercise. Plasma catecholamines also appeared to be lower after exercise training, although this effect was not statistically significant. Plasma levels of chromogranin A and aldosterone measured at rest and maximal exercise were not influenced by the exercise regimen. Further controlled studies are required to corroborate the results of this preliminary study.
It has been suggested that the systolic blood pressure (SBP) response to exercise may be useful in predicting future hypertension. However, controversy exists as to whether the SBP response to exercise in borderline hypertensives is actually greater than normotensives or merely increases equally but from a higher resting value. Our aim was to determine the influence of resting SBP, age and sex on changes of SSP during exercise for both healthy subjects and untreated mild hypertensives. Three hundred and eighteen (230 males) underwent a self limited exercise protocol. SBP was measured at baseline and between the 2nd and 3rd minutes of each exercise stage. Age was positively related to SBP at rest and during exercise. The magnitude of SBP change induced by exercise was similar irrespective of the level of resting SBP. The relationship between resting SBP and the absolute SBP change which occurred during exercise was independent of sex. Our findings indicate that (i) age is positively related to SBP at rest and during exercise, (ii) SBP rises equally during exercise irrespective of its resting level and (iii) males and females have a similar pattern of BP response to exercise.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.