Increased cerebral vascular resistance underlies preserved cerebral blood flow in response to orthostasis in humans on a high-salt diet

Dumančić, Dijana; Stupin, Ana; Kožul, Maja; Šerić, Vatroslav; Kibel, Aleksandar; Goswami, Nandu; Brix, Bianca; Debeljak, Željko; Scitovski, Rudolf; Drenjančević-Perić, Ines

doi:10.1007/s00421-022-05124-w

Cited by 3 publications

(4 citation statements)

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“…This usually occurs in circumstances where an individual remains in an upright position for a prolonged duration, leading to the accumulation of blood in the lower extremities and consequent impairment of blood flow to the heart and brain ( 3 ). Central hypovolemia triggers hypotensive activation of arterial and cardiopulmonary baroreflexes, which leads to a neurohumoral-mediated increase in heart rate and vasoconstriction to maintain blood pressure and blood flow to vital organs ( 4 , 5 ). However, in some individuals, these compensatory responses are inadequate, and orthostatic intolerance develops ( 6 ).…”

Section: Introductionmentioning

confidence: 99%

Association of gender with cardiovascular and autonomic responses to central hypovolemia

Shankhwar,

Urvec,

Steuber

et al. 2023

Front. Cardiovasc. Med.

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IntroductionLower body negative pressure (LBNP) eliminates the impact of weight-bearing muscles on venous return, as well as the vestibular component of cardiovascular and autonomic responses. We evaluated the hemodynamic and autonomic responses to central hypovolemia, induced by LBNP in both males and females.MethodologyA total of 44 participants recruited in the study. However, 9 participants did not complete the study protocol. Data from the remaining 35 participants were analysed, 18 males (25.28 ± 3.61 years, 181.50 ± 7.43 cm height, 74.22 ± 9.16 kg weight) and 17 females (22.41 ± 2.73 years, 167.41 ± 6.29 cm height, 59.06 ± 6.91 kg weight). During the experimental protocol, participants underwent three phases, which included 30 min of supine rest, four 4 min intervals of stepwise increases in LBNP from −10 mmHg to −40 mmHg, and 5 min of supine recovery. Throughout the protocol, hemodynamic variables such as blood pressure, heart rate, stroke index, cardiac index, and total peripheral resistance index were continuously monitored. Autonomic variables were calculated from heart rate variability measures, using low and high-frequency spectra, as indicators of sympathetic and parasympathetic activity, respectively.ResultsAt rest, males exhibited higher systolic (118.56 ± 9.59 mmHg and 110.03 ± 10.88 mmHg, p < 0.05) and mean arterial (89.70 ± 6.86 and 82.65 ± 9.78, p < 0.05) blood pressure as compared to females. Different levels of LBNP altered hemodynamic variables in both males and females: heart rate [F(1,16) = 677.46, p < 0.001], [F(1,16) = 550.87, p < 0.001]; systolic blood pressures [F(1,14) = 3,186.77, p < 0.001], [F(1,17) = 1,345.61, p < 0.001]; diastolic blood pressure [F(1,16) = 1,669.458, p < 0.001], [F(1,16) = 1,127.656, p < 0.001]; mean arterial pressures [F(1,16) = 2,330.44, p < 0.001], [F(1,16) = 1,815.68, p < 0.001], respectively. The increment in heart rates during LBNP was significantly different between both males and females (p = 0.025). The low and high-frequency powers were significantly different for males and females (p = 0.002 and p = 0.001, respectively), with the females having a higher increase in low-frequency spectral power.Conclusions and future directionsCardiovascular activity and autonomic function at rest are influenced by gender. During LBNP application, hemodynamic and autonomic responses differed between genders. These gender-based differences in responses during central hypovolemia could potentially be attributed to the lower sympathetic activity in females. With an increasing number of female crew members in space missions, it is important to understand the role sex-steroid hormones play in the regulation of cardiovascular and autonomic activity, at rest and during LBNP.

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Section: Introductionmentioning

confidence: 99%

Association of gender with cardiovascular and autonomic responses to central hypovolemia

Shankhwar,

Urvec,

Steuber

et al. 2023

Front. Cardiovasc. Med.

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“…The role of excessive salt intake in hypertension and the health benefits of salt reduction are very well documented [ 1 , 2 , 3 ]. Although sodium is essential for almost all physiological functions, from nutrient absorption to nervous impulse transmission and muscle contraction [ 4 , 5 , 6 ], in excess it adversely impacts the metabolism [ 7 ], immunity [ 8 ], fibrosis [ 9 ], and cardiopulmonary work [ 10 , 11 , 12 ] among many other effects. In a rat model, salt-elevated food with NaCl concentration exceeding 4% (like in the human-used processed meats and soups) was shown to exacerbate the development of various types of cardiomyopathy [ 13 ] leading to heart failure.…”

Section: Introductionmentioning

confidence: 99%

Low-Salt Diet Regulates the Metabolic and Signal Transduction Genomic Fabrics, and Remodels the Cardiac Normal and Chronic Pathological Pathways

Iacobas,

Allen,

Iacobas

2024

CIMB

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Low-salt diet (LSD) is a constant recommendation to hypertensive patients, but the genomic mechanisms through which it improves cardiac pathophysiology are still not fully understood. Our publicly accessible transcriptomic dataset of the left ventricle myocardium of adult male mice subjected to prolonged LSD or normal diet was analyzed from the perspective of the Genomic Fabric Paradigm. We found that LSD shifted the metabolic priorities by increasing the transcription control for fatty acids biosynthesis while decreasing it for steroid hormone biosynthesis. Moreover, LSD remodeled pathways responsible for cardiac muscle contraction (CMC), chronic Chagas (CHA), diabetic (DIA), dilated (DIL), and hypertrophic (HCM) cardiomyopathies, and their interplays with the glycolysis/glucogenesis (GLY), oxidative phosphorylation (OXP), and adrenergic signaling in cardiomyocytes (ASC). For instance, the statistically (p < 0.05) significant coupling between GLY and ASC was reduced by LSD from 13.82% to 2.91% (i.e., −4.75×), and that of ASC with HCM from 10.50% to 2.83% (−3.71×). The substantial up-regulation of the CMC, ASC, and OXP genes, and the significant weakening of the synchronization of the expression of the HCM, CHA, DIA, and DIL genes within their respective fabrics justify the benefits of the LSD recommendation.

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“…The lower body negative pressure (LBNP) technique can be used to assess cardiovascular responses and stability during central hypovolemia ( 3 , 4 ). The application of LBNP shifts the blood from the upper body to the lower body and leads to a decrease in the amount of blood returning to the heart ( 5 , 6 ). The release of LBNP is rapidly followed by returning of blood from the lower limbs to the torso region in healthy young adults ( 7 ).…”

Section: Introductionmentioning

confidence: 99%

“…This study aims to explore the influence of menstrual phases on cardiovascular and autonomic responses in both resting and during the central hypovolemia induced by lower body negative pressure (LBNP) ( 6 , 7 , 20 – 22 ). This is a companion paper, in which data across the menstrual phases from healthy young females, whose results are reported in Shankwar et al, were further analysed ( 23 ).…”

Section: Introductionmentioning

confidence: 99%

Effects of menstrual cycle on hemodynamic and autonomic responses to central hypovolemia

Shankhwar,

Urvec,

Steuber

et al. 2024

Front. Cardiovasc. Med.

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BackgroundEstrogen and progesterone levels undergo changes throughout the menstrual cycle. Existing literature regarding the effect of menstrual phases on cardiovascular and autonomic regulation during central hypovolemia is contradictory.Aims and studyThis study aims to explore the influence of menstrual phases on cardiovascular and autonomic responses in both resting and during the central hypovolemia induced by lower body negative pressure (LBNP). This is a companion paper, in which data across the menstrual phases from healthy young females, whose results are reported in Shankwar et al. (2023), were further analysed.MethodsThe study protocol consisted of three phases: (1) 30 min of supine rest; (2) 16 min of four LBNP levels; and (3) 5 min of supine recovery. Hemodynamic and autonomic responses (assessed via heart rate variability, HRV) were measured before-, during-, and after-LBNP application using Task Force Monitor® (CNSystems, Graz, Austria). Blood was also collected to measure estrogen and progesterone levels.ResultsIn this companion paper, we have exclusively assessed 14 females from the previous study (Shankwar et al., 2023): 8 in the follicular phase of the menstrual cycle (mean age 23.38 ± 3.58 years, height 166.00 ± 5.78 cm, weight 57.63 ± 5.39 kg and BMI of 20.92 ± 1.96 25 kg/m2) and 6 in the luteal phase (mean age 22.17 ± 1.33 years, height 169.83 ± 5.53 cm, weight 62.00 ± 7.54 kg and BMI of 21.45 ± 2.63 kg/m2). Baseline estrogen levels were significantly different from the follicular phase as compared to the luteal phase: (33.59 pg/ml, 108.02 pg/ml, respectively, p < 0.01). Resting hemodynamic variables showed no difference across the menstrual phases. However, females in the follicular phase showed significantly lower resting values of low-frequency (LF) band power (41.38 ± 11.75 n.u. and 58.47 ± 14.37 n.u., p = 0.01), but higher resting values of high frequency (HF) band power (58.62 ± 11.75 n.u. and 41.53 ± 14.37 n.u., p = 0.01), as compared to females in the luteal phase. During hypovolemia, the LF and HF band powers changed only in the follicular phase F(1, 7) = 77.34, p < 0.0001 and F(1, 7) = 520.06, p < 0.0001, respectively.ConclusionsThe menstrual phase had an influence on resting autonomic variables, with higher sympathetic activity being observed during the luteal phase. Central hypovolemia leads to increased cardiovascular and autonomic responses, particularly during the luteal phase of the menstrual cycle, likely due to higher estrogen levels and increased sympathetic activity.

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Increased cerebral vascular resistance underlies preserved cerebral blood flow in response to orthostasis in humans on a high-salt diet

Cited by 3 publications

References 36 publications

Association of gender with cardiovascular and autonomic responses to central hypovolemia

Association of gender with cardiovascular and autonomic responses to central hypovolemia

Low-Salt Diet Regulates the Metabolic and Signal Transduction Genomic Fabrics, and Remodels the Cardiac Normal and Chronic Pathological Pathways

Effects of menstrual cycle on hemodynamic and autonomic responses to central hypovolemia

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