Effects of Vasodilation and Arterial Resistance on Cardiac Output

Siddiqui, Aliya

doi:10.4172/2155-9880.1000170

Cited by 22 publications

(14 citation statements)

References 63 publications

(66 reference statements)

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“…Taller individuals have a longer distance for blood to travel from the lower legs to the heart. Therefore, these individuals would require larger external forces to generate sufficient pressure to translocate blood the extra distance back to the heart as characterized by the relationship between pressure and length of a tube in Poiseuille's equation . This suggests that CS may provide insufficient external pressures to enhance venous return in taller individuals with smaller lower leg circumference.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, these individuals would require larger external forces to generate sufficient pressure to translocate blood the extra distance back to the heart as characterized by the relationship between pressure and length of a tube in Poiseuille's equation. 26 This suggests that CS may provide insufficient external pressures to enhance venous return in taller individuals with smaller lower leg circumference. Previous findings by Protheroe et al 14 demonstrated a positive relationship between the body height:lower leg circumference ratio and changes in orthostatic tolerance after combined HUT and lower body negative pressure in young healthy volunteers.…”

Section: Anthropometric Variabilitymentioning

confidence: 99%

See 1 more Smart Citation

Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

Dorey

O’Brien

Robinson

et al. 2018

Scandinavian Med Sci Sports

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In healthy individuals during a non-exercised state, knee-high compression socks (CS) may reduce the magnitude of lower limb venous pooling during orthostasis but are not effective at minimizing the incidence of pre-syncopal symptoms. However, exaggerated reductions in cerebral blood flow velocity (CBV) and cardiac stroke volume (SV) occur during passive head-up tilt (HUT) testing following dynamic exercise. It is unknown if CS can minimize post-exercise HUT-induced decrements in CBV and SV in this population. To test the hypothesis that CS will attenuate the reductions in SV and CBV during 60° HUT following 60 minutes of moderate-intensity (60% VO peak) cycling exercise. Ten healthy volunteers (22.6 ± 2.1 years, 24.1 ± 2.5 kg/m ) completed pre- and post-exercise 15-minute HUT tests during randomized CS and Control (no CS) conditions. Changes in blood pressure (finger plethysmography), SV (Modelflow® method), and CBV (Transcranial Doppler) were measured during HUT and preceding supine rest periods. Pre-exercise HUT-induced similar (all, P > .47) reductions in SV (Control; -23.1 ± 11.5%, CS; -20.5 ± 10.9%) and CBV (Control; -18.1 ± 6.3%, CS; -15.3 ± 9.0%). However, larger post-exercise decreases in SV and CBV during HUT were observed in the Control versus CS condition. Specifically, CS attenuated the drop in SV (Control: -32.9 ± 5.6%, CS: -24.3 ± 11.6%; P = .01) and CBV (Control: -25.1 ± 5.8%, CS: -17.6 ± 7.8%; P = .02) during the post-exercise HUT test. These results indicate that CS attenuated HUT-induced reductions in SV and CBV following moderate-intensity cycling exercise and suggest that CS may be an effective countermeasure to reduce the incidence of post-exercise syncope in vulnerable populations.

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Section: Discussionmentioning

confidence: 99%

Section: Anthropometric Variabilitymentioning

confidence: 99%

Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

Dorey

O’Brien

Robinson

et al. 2018

Scandinavian Med Sci Sports

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“…With no other physiological adjustments, the enlargement of the infrarenal IVC with increasing core temperature that we quantified here would act to minimize increases in blood velocity with increased cardiac output (Crandall ; Siddiqui ; Crouch et al. ), and increase counter‐current heat exchange, potentially leading to deleterious effects as more heat is transferred centrally.…”

Section: Discussionmentioning

confidence: 99%

“…; Bain et al. ), increased cardiac output (Crandall ; Siddiqui ), and decreased total peripheral resistance (Kuhn and Turner ; Crandall ). Absent from this previous work was empirical data regarding geometric (size and shape) and functional (deformation across cardiac cycle) changes in core vessels, which are necessary for improved parameterization and validation of mathematical and computational models(Wissler ; Bhowmik et al.…”

Section: Introductionmentioning

confidence: 99%

Cross-sectional areas of deep/core veins are smaller at lower core body temperatures

2018

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The cardiovascular system plays a crucial role in thermoregulation. Deep core veins, due to their large size and role in returning blood to the heart, are an important part of this system. The response of veins to increasing core temperature has not been adequately studied in vivo. Our objective was to noninvasively quantify in C57BL/6 mice the response of artery‐vein pairs to increases in body temperature. Adult male mice were anesthetized and underwent magnetic resonance imaging. Data were acquired from three colocalized vessel pairs (the neck [carotid/jugular], torso [aorta/inferior vena cava (IVC)], periphery [femoral artery/vein]) at core temperatures of 35, 36, 37, and 38°C. Cross‐sectional area increased with increasing temperature for all vessels, excluding the carotid. Average area of the jugular, aorta, femoral artery, and vein linearly increased with temperature (0.10, 0.017, 0.017, and 0.027 mm2/°C, respectively; P < 0.05). On average, the IVC has the largest venous response for area (18.2%/°C, vs. jugular 9.0 and femoral 10.9%/°C). Increases in core temperature from 35 to 38 °C resulted in an increase in contact length between the aorta/IVC of 29.3% (P = 0.007) and between the femoral artery/vein of 28.0% (P = 0.03). Previously unidentified increases in the IVC area due to increasing core temperature are biologically important because they may affect conductive and convective heat transfer. Vascular response to temperature varied based on location and vessel type. Leveraging noninvasive methodology to quantify vascular responses to temperature could be combined with bioheat modeling to improve understanding of thermoregulation.

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“…Locomotor activity positively correlates with heart rate in the rat [60], and increased heart rate is linked to increased vasodilatation in the body [61], which may have induced the change in ear colour. Thus, differences in physical activity between treatments could explain Ear Colour change.…”

Section: Discussionmentioning

confidence: 99%

Facial Indicators of Positive Emotions in Rats

et al. 2016

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Until recently, research in animal welfare science has mainly focused on negative experiences like pain and suffering, often neglecting the importance of assessing and promoting positive experiences. In rodents, specific facial expressions have been found to occur in situations thought to induce negatively valenced emotional states (e.g., pain, aggression and fear), but none have yet been identified for positive states. Thus, this study aimed to investigate if facial expressions indicative of positive emotional state are exhibited in rats. Adolescent male Lister Hooded rats (Rattus norvegicus, N = 15) were individually subjected to a Positive and a mildly aversive Contrast Treatment over two consecutive days in order to induce contrasting emotional states and to detect differences in facial expression. The Positive Treatment consisted of playful manual tickling administered by the experimenter, while the Contrast Treatment consisted of exposure to a novel test room with intermittent bursts of white noise. The number of positive ultrasonic vocalisations was greater in the Positive Treatment compared to the Contrast Treatment, indicating the experience of differentially valenced states in the two treatments. The main findings were that Ear Colour became significantly pinker and Ear Angle was wider (ears more relaxed) in the Positive Treatment compared to the Contrast Treatment. All other quantitative and qualitative measures of facial expression, which included Eyeball height to width Ratio, Eyebrow height to width Ratio, Eyebrow Angle, visibility of the Nictitating Membrane, and the established Rat Grimace Scale, did not show differences between treatments. This study contributes to the exploration of positive emotional states, and thus good welfare, in rats as it identified the first facial indicators of positive emotions following a positive heterospecific play treatment. Furthermore, it provides improvements to the photography technique and image analysis for the detection of fine differences in facial expression, and also adds to the refinement of the tickling procedure.

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Effects of Vasodilation and Arterial Resistance on Cardiac Output

Cited by 22 publications

References 63 publications

Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

Cross-sectional areas of deep/core veins are smaller at lower core body temperatures

Facial Indicators of Positive Emotions in Rats

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