Abnormal Muscle Metaboreflex Control of Sympathetic Activity in Never-Treated Hypertensive Subjects

Rondon, Maria Urbana Pinto Brandão; Laterza, Mateus Camaroti; Matos, Luciana Diniz Nagem Janot de; Trombetta, Ivani C.; Braga, Ana Maria W.; Roveda, Fabiana; Alves, Maria Janieire N. N.; Krieger, E M; Negräo, Carlos Eduardo

doi:10.1016/j.amjhyper.2006.02.001

Cited by 64 publications

(88 citation statements)

References 24 publications

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“…24 The increase in diastolic blood pressure after water ingestion found in hypertensive and normotensive subjects was similar to that observed in patients with multiple system atrophy and pure autonomic failure with sympathetic denervation. 1 In agreement with previous observations, 25 our subjects with mild hypertension showed higher baseline MSNA when compared to normotensive subjects. However, forearm vascular resistance, parasympathetic nervous activity and spontaneous baroreflex sensitivity at baseline of our mildly hypertensive subjects were similar to normotensive individuals.…”

Section: Discussionsupporting

confidence: 81%

“…Other studies have shown that arterial hypertension is accompanied by an increased forearm vascular resistance, impairment of the baroreflex regulation, and reduced parasympathetic modulations to the sinus node. [25][26][27] However, it is possible that the group of hypertensive patients in our study could be at an early stage of their natural history, before these haemodynamic and autonomic changes are apparent. .…”

Section: Discussionmentioning

confidence: 95%

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Acute water ingestion increases arterial blood pressure in hypertensive and normotensive subjects

et al. 2007

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In patients with severe autonomic dysfunction, water ingestion elicits an acute pressor response. Hypertension may be associated with changes in cardiovascular autonomic modulation, but there is no information on the acute effects of water ingestion in patients with hypertension. In this study, we compared the effect of acute water ingestion on haemodynamic and autonomic responses of hypertensive and normotensive individuals. Eight patients with mild hypertension were compared to 10 normotensive individuals. After 30 min resting in the supine position all subjects ingested 500 ml of water. At baseline and after water ingestion, venous blood samples for plasma volume determination were collected, and electrocardiographic tracings, finger blood pressure, forearm blood flow and muscle sympathetic nerve activity (MSNA) were obtained. Water ingestion resulted in similar and minor reduction in plasma volume. Systolic and diastolic blood pressure increased in both hypertensive (mean7s.d.: 19/1476/ 3 mm Hg) and normotensive subjects (17/1476/3 mm Hg). There was an increase in forearm vascular resistance and in MSNA. Heart rate was reduced (hypertensive: 571 beats/min, normotensive: 576 beats/min) and the high-frequency component of heart rate and systolic blood pressure variability was increased. In hypertensive and normotensive individuals, acute water ingestion elicits a pressor response, an effect that is most likely determined by an increased vasoconstrictor sympathetic activity, and is counterbalanced by an increase in blood pressure and heart rate vagal modulation.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 95%

Acute water ingestion increases arterial blood pressure in hypertensive and normotensive subjects

et al. 2007

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“…After the maximum voluntary contraction (MVC; average of three trials) was obtained, handgrip isometric exercise was performed at 30% of MVC with the dominant arm using a handgrip dynamometer. It has been shown that this strategy causes substantial nonexercise muscle vasodilatation in humans (1,25,30). Handgrip isometric exercise has been used to assess vascular function in adults and children (2,24,30).…”

Section: Measurements and Proceduresmentioning

confidence: 99%

Glu298Asp eNOS gene polymorphism causes attenuation in nonexercising muscle vasodilatation

Dias

Alves

Pereira

et al. 2009

Physiological Genomics

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“…Blood pressure was monitored noninvasively and intermittently with an automatic and oscillometric cuff (Dixtal, DX 2710; Manaus, Brazil) placed on the ankle with a cuff width adjusted to ankle circumference (24,29). The cuff inflated every 30 s. Heart rate was monitored continuously through lead II of EKG.…”

Section: Measurements and Proceduresmentioning

confidence: 99%

“…After the maximum voluntary contraction (MVC; average of three trials) was obtained, handgrip isometric exercise was performed at 30% of MVC with the dominant arm using a handgrip dynamometer. It has been shown that this strategy causes substantial nonexercise muscle vasodilatation in humans (3,29,35). The individuals were instructed to breath normally during exercise and to avoid inadvertent performance of Valsalva maneuver.…”

Section: Measurements and Proceduresmentioning

confidence: 99%

Exercise training improves muscle vasodilatation in individuals with T786C polymorphism of endothelial nitric oxide synthase gene

Negrão

Alves

et al. 2010

Physiological Genomics

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Rondon MU. Exercise training improves muscle vasodilatation in individuals with T786C polymorphism of endothelial nitric oxide synthase gene. Physiol Genomics 42A: 71-77, 2010. First published July 6, 2010; doi:10.1152/physiolgenomics.00145.2009.-Allele T at promoter region of the eNOS gene has been associated with an increase in coronary disease mortality, suggesting that this allele increases susceptibility for endothelial dysfunction. In contrast, exercise training improves endothelial function. Thus, we hypothesized that: 1) Muscle vasodilatation during exercise is attenuated in individuals homozygous for allele T, and 2) Exercise training improves muscle vasodilatation in response to exercise for TT genotype individuals. From 133 preselected healthy individuals genotyped for the T786C polymorphism, 72 participated in the study: TT (n ϭ 37; age 27 Ϯ 1 yr) and CTϩCC (n ϭ 35; age 26 Ϯ 1 yr). Forearm blood flow (venous occlusion plethysmography) and blood pressure (oscillometric automatic cuff) were evaluated at rest and during 30% handgrip exercise. Exercise training consisted of three sessions per week for 18 wk, with intensity between anaerobic threshold and respiratory compensation point. Resting forearm vascular conductance (FVC, P ϭ 0.17) and mean blood pressure (P ϭ 0.70) were similar between groups. However, FVC responses during handgrip exercise were significantly lower in TT individuals compared with CTϩCC individuals (0.39 Ϯ 0.12 vs. 1.08 Ϯ 0.27 units, P ϭ 0.01). Exercise training significantly increased peak VO 2 in both groups, but resting FVC remained unchanged. This intervention significantly increased FVC response to handgrip exercise in TT individuals (P ϭ 0.03), but not in CTϩCC individuals (P ϭ 0.49), leading to an equivalent FVC response between TT and CTϩCC individuals (1.05 Ϯ 0.18 vs. 1.59 Ϯ 0.27 units, P ϭ 0.27). In conclusion, exercise training improves muscle vasodilatation in response to exercise in TT genotype individuals, demonstrating that genetic variants influence the effects of interventions such as exercise training. genetics NITRIC OXIDE (NO) is synthesized in the endothelium by the endothelial isoform of nitric oxide synthase (eNOS) (27), a protein encoded in the long arm of chromosome 7 (19). NO is responsible for the maintenance of vascular tone due to its capability of inducing vasodilatation in response to shear stress (9, 26). A disruption of eNOS function or of its production can decrease NO bioavailability and, consequently, lead to deleterious effects on endothelial and vasomotor function. Recent findings suggest that, apart from classic risk factors such as smoking and diabetes, genetic variants are capable of altering eNOS expression and enzymatic activity (21,23,36).Among the genetic variants present in the eNOS gene, considerable attention has been focused on the T786C polymorphism, which is located on the 5=-flanking region of the promoter region of the eNOS gene. The C allele of this polymorphism has been associated with coronary spasm (23) and blunted vasodilato...

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Abnormal Muscle Metaboreflex Control of Sympathetic Activity in Never-Treated Hypertensive Subjects

Abstract: These findings suggest an association between hypertension and decreased muscle metaboreflex control of MSNA.

Cited by 64 publications

References 24 publications

Acute water ingestion increases arterial blood pressure in hypertensive and normotensive subjects

Acute water ingestion increases arterial blood pressure in hypertensive and normotensive subjects

Glu298Asp eNOS gene polymorphism causes attenuation in nonexercising muscle vasodilatation

Exercise training improves muscle vasodilatation in individuals with T786C polymorphism of endothelial nitric oxide synthase gene

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