Electrolyte Changes in Plasma and Urine of Athletes During Acute and Rigorous Bed Rest and Ambulatory Conditions

The effect of high NaCl diet on resistance arteries is not yet fully documented. In order to assess the effect of NaCl on myogenic tone and flow-induced dilation independent of arterial blood pressure change, we used normotensive rats which did not develop hypertension upon high NaCl intake. Normotensive Wistar Kyoto Rats received a high (8%) or a normal NaCl diet (0.4%). Mesenteric resistance arteries (150 mm, internal diameter) were cannulated in an arteriograph to allow perfusion of arteries under controlled pressure and flow. Pressure-induced myogenic tone was lower in the high NaCl group than in the control group. Cyclooxygenase inhibition with indomethacin and (N-(2-cyclohexyloxy)-4-nitro-phenyl)-methanesulphonamide, 1 mmol/l) NS 398 (specific cyclooxygenase-2 inhibitor) similarly decreased myogenic tone in rats fed high NaCl but had no effect in those fed a normal NaCl diet. Flow-induced dilation was decreased in the high NaCl group. Inhibition of nitric oxide synthesis with N G -nitro-L-arginine methyl ester decreased flow-induced dilation in both groups. Indomethacin and NS 398 did not change flow-induced dilation. As shown by immunofluorescence COX-2 was present in the endothelium of arteries from rats with a high NaCl diet but not in those fed a normal NaCl diet. Thus, chronic high NaCl intake decreased both flow-induced dilation and myogenic tone in resistance arteries. The chronic high NaCl did not affect the participation of nitric oxide on flow-induced dilation, but induced the expression of cyclooxygenase-2, which participates in myogenic tone. These results suggest that high NaCl changes flow and pressure mechanosensing processes and strengthen the hypothesis that sodium ions have an important role in both pressure and flow-mechanotransduction in vascular cells.

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“…from blood plasma. The concentration of sodium from plasma was done by flame photometry (Zorbas et al 2001).…”

Section: Methodsmentioning

confidence: 99%

High NaCl Intake Decreases both Flow‐Induced Dilation and Pressure‐Induced Myogenic Tone in Resistance Arteries from Normotensive Rats: Involvement of Cyclooxygenase‐2

Matrougui

Loufrani

Lévy

et al. 2001

Pharmacology & Toxicology

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Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis

Ried‐Larsen

Aarts

Joyner

2017

Journal of Applied Physiology

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The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (V̇o) and to explore sources of variation therein. Since 1949, 80 studies with a total of 949 participants (>90% men) have been published with data on strict bed rest and V̇o The studies were conducted mainly in young participants [median age (interquartile range) 24.5 (22.4-34.0) yr]. The duration of bed rest ranged from 1 to 90 days. V̇o declined linearly across bed rest duration. No statistical difference in the decline among studies reporting V̇o as l/min (-0.3% per day) compared with studies reporting V̇o normalized to body weight (ml·kg·min; -0.43% per day) was observed. Although both total body weight and lean body mass declined in response to bed rest, we did not see any associations with the decline in V̇o However, 15-26% of the variation in the decline in V̇o was explained by the pre-bed-rest V̇o levels, independent of the duration of bed rest (i.e., higher pre-bed-rest V̇o levels were associated with larger declines in V̇o). Furthermore, the systematic review revealed a gap in the knowledge about the cardiovascular response to extreme physical inactivity, particularly in older subjects and women of any age group. In addition to its relevance to spaceflight, this lack of data has significant translational implications because younger women sometimes undergo prolonged periods of bed rest associated with the complications of pregnancy and the incidence of hospitalization including prolonged periods of bed rest increases with age. Large interindividual responses of maximal oxygen uptake (V̇o) to aerobic exercise training exist. However, less is known about the variability in the response of V̇o to prolonged bed rest. This systematic review and meta-analysis showed that pre-bed-rest V̇o values were inversely associated with the change in V̇o independent of the duration of bed rest. Moreover, we identified a large knowledge gap about the causes of decline in V̇o, particularly in postmenopausal women, which may have clinical implications.

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Electrolyte Changes in Plasma and Urine of Athletes During Acute and Rigorous Bed Rest and Ambulatory Conditions

Cited by 2 publications

References 10 publications

High NaCl Intake Decreases both Flow‐Induced Dilation and Pressure‐Induced Myogenic Tone in Resistance Arteries from Normotensive Rats: Involvement of Cyclooxygenase‐2

High NaCl Intake Decreases both Flow‐Induced Dilation and Pressure‐Induced Myogenic Tone in Resistance Arteries from Normotensive Rats: Involvement of Cyclooxygenase‐2

Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis

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