Key result
High sodium intake of 15 g/day for 7 days increased mean arterial pressure but did not alter functional sympatholysis during handgrip exercise in healthy humans (p > 0.05).
Why the study?
High dietary sodium is a risk factor for hypertension and functional sympatholysis is attenuated in hypertension, prompting investigation into cardiovascular responses to high salt intake in healthy humans.
Does high sodium intake of 15 g/day for 7 days attenuate functional sympatholysis and augment blood pressure response to handgrip exercise in healthy humans?
Does high sodium intake of 15 g/day for 7 days attenuate functional sympatholysis and augment blood pressure response to handgrip exercise in healthy humans?
One week of high sodium intake increases blood pressure and impairs endothelial function (FMD) but does not affect functional sympatholysis during exercise in healthy humans.
High sodium raises mean arterial pressure without impairing functional sympatholysis; extends evidence that its pressor effect acts independently of exercise-mediated vasodilation.
High dietary sodium intake is a risk factor for arterial hypertension; given that the ability to overcome sympathetically mediated vasoconstriction (functional sympatholysis) is attenuated in individuals with hypertension, we investigated the cardiovascular responses to high salt (HS) intake in healthy humans. We hypothesized that a HS intake of 15 g/day for 7 days would attenuate functional sympatholysis and augment the blood pressure response to handgrip exercise (HGE). Thirteen participants (6 males, 7 females) underwent 2 individual days of testing. Beat-by-beat blood pressure and heart rate were recorded throughout the trial on the non-exercising limb. Forearm blood flow was derived from ultrasonography on the brachial artery of the exercising limb. Participants then underwent a flow-mediated dilation (FMD) test. Next, a submaximal HGE was performed for 7 min with lower body negative pressure initiated during minutes 5–7. A single spot urine sample revealed a significant increase in sodium excretion during the HS conditions (p < 0.01). FMD was reduced during the HS condition. Mean arterial pressure was significantly higher during HS intake. No alteration to functional sympatholysis was found between conditions (p > 0.05). In summary, HS intake increases blood pressure without impacting functional sympatholysis or blood pressure responsiveness during HGE. These findings indicate that brachial artery dysfunction precedes an inefficient functional sympatholysis. Novelty Functional sympatholysis was not impacted by 1 week of high sodium intake. High sodium intake augmented the rate pressure product during handgrip exercise in healthy humans.
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Caldwell et al. (2019) studied Healthy humans (n=13). High salt (HS) intake vs. Baseline/control condition was evaluated on Functional sympatholysis (p=> 0.05). High sodium intake of 15 g/day for 7 days increased mean arterial pressure but did not alter functional sympatholysis during handgrip exercise in healthy humans (p > 0.05).
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