Skin Blood Flow and Vascular Endothelium Function in Uremia

Abstract Purpose This study assessed the impact of normobaric hypoxia and acute nitrate ingestion on shivering thermogenesis, cutaneous vascular control, and thermometrics in response to cold stress. Method Eleven male volunteers underwent passive cooling at 10 °C air temperature across four conditions: (1) normoxia with placebo ingestion, (2) hypoxia (0.130 FiO2) with placebo ingestion, (3) normoxia with 13 mmol nitrate ingestion, and (4) hypoxia with nitrate ingestion. Physiological metrics were assessed as a rate of change over 45 min to determine heat loss, and at the point of shivering onset to determine the thermogenic thermoeffector threshold. Result Independently, hypoxia expedited shivering onset time (p = 0.05) due to a faster cooling rate as opposed to a change in central thermoeffector thresholds. Specifically, compared to normoxia, hypoxia increased skin blood flow (p = 0.02), leading to an increased core-cooling rate (p = 0.04) and delta change in rectal temperature (p = 0.03) over 45 min, yet the same rectal temperature at shivering onset (p = 0.9). Independently, nitrate ingestion delayed shivering onset time (p = 0.01), mediated by a change in central thermoeffector thresholds, independent of changes in peripheral heat exchange. Specifically, compared to placebo ingestion, no difference was observed in skin blood flow (p = 0.5), core-cooling rate (p = 0.5), or delta change in rectal temperature (p = 0.7) over 45 min, while nitrate reduced rectal temperature at shivering onset (p = 0.04). No interaction was observed between hypoxia and nitrate ingestion. Conclusion These data improve our understanding of how hypoxia and nitric oxide modulate cold thermoregulation.

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Using reactive hyperemia to investigate the effect of cupping sizes of cupping therapy on skin blood flow responses

Journal of Back and Musculoskeletal Rehabilitation ◽

10.3233/bmr-200120 ◽

2021 ◽

pp. 1-7

Author(s):

Xiangfeng He ◽

Xueyan Zhang ◽

Fuyuan Liao ◽

Li He ◽

Xin Xu ◽

...

Keyword(s):

Blood Flow ◽

Laser Doppler Flowmetry ◽

Skin Blood Flow ◽

Repeated Measures ◽

Recovery Time ◽

Reactive Hyperemia ◽

Cupping Therapy ◽

Doppler Flowmetry ◽

Healthy Participants ◽

Hyperemic Response

BACKGROUND: Various cupping sizes of cupping therapy have been used in managing musculoskeletal conditions; however, the effect of cupping sizes on skin blood flow (SBF) responses is largely unknown. OBJECTIVE: The objective of this study was to compare the effect of three cupping sizes of cupping therapy on SBF responses. METHODS: Laser Doppler flowmetry (LDF) was used to measure SBF on the triceps in 12 healthy participants in this repeated measures study. Three cup sizes (35, 40 and 45 mm in diameter) were blinded to the participants and were tested at -300 mmHg for 5 minutes. Reactive hyperemic response to cupping therapy was expressed as a ratio of baseline SBF. RESULTS: All three sizes of cupping cups resulted in a significant increase in peak SBF (p< 0.001). Peak SBF of the 45 mm cup (9.41 ± 1.32 times) was significantly higher than the 35 mm cup (5.62 ± 1.42 times, p< 0.05). Total SBF of the 45 mm cup ((24.33 ± 8.72) × 103 times) was significantly higher than the 35 mm cup ((8.05 ± 1.63) × 103 times, p< 0.05). Recovery time of the 45 mm cup (287.46 ± 39.54 seconds) was significantly longer than the 35 mm cup (180.12 ± 1.42 seconds, p< 0.05). CONCLUSIONS: Our results show that all three cup sizes can significantly increase SBF. The 45 mm cup is more effective in increasing SBF compared to the 35 mm cup.

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Adrenergic control of vascular resistance varies in muscles composed of different fiber types: influence of the vascular endothelium

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00205.2011 ◽

2011 ◽

Vol 301 (3) ◽

pp. R783-R790 ◽

Cited By ~ 26

Author(s):

Bradley J. Behnke ◽

Robert B. Armstrong ◽

Michael D. Delp

Keyword(s):

Blood Flow ◽

Vascular Resistance ◽

Vascular Endothelium ◽

Fold Increase ◽

Male Rats ◽

Type I ◽

Fiber Types ◽

Fast Twitch Muscle ◽

Dose Responses ◽

Fast Twitch

The influence of the sympathetic nervous system (SNS) upon vascular resistance is more profound in muscles comprised predominately of low-oxidative type IIB vs. high-oxidative type I fiber types. However, within muscles containing high-oxidative type IIA and IIX fibers, the role of the SNS on vasomotor tone is not well established. The purpose of this study was to examine the influence of sympathetic neural vasoconstrictor tone in muscles composed of different fiber types. In adult male rats, blood flow to the red and white portions of the gastrocnemius (GastRed and GastWhite, respectively) and the soleus muscle was measured pre- and postdenervation. Resistance arterioles from these muscles were removed, and dose responses to α1-phenylephrine or α2-clonidine adrenoreceptor agonists were determined with and without the vascular endothelium. Denervation resulted in a 2.7-fold increase in blood flow to the soleus and GastRed and an 8.7-fold increase in flow to the GastWhite. In isolated arterioles, α2-mediated vasoconstriction was greatest in GastWhite (∼50%) and less in GastRed (∼31%) and soleus (∼17%); differences among arterioles were abolished with the removal of the endothelium. There was greater sensitivity to α1-mediated vasoconstriction in the GastWhite and GastRed vs. the soleus, which was independent of whether the endothelium was present. These data indicate that 1) control of vascular resistance by the SNS in high-oxidative, fast-twitch muscle is intermediate to that of low-oxidative, fast-twitch and high-oxidative, slow-twitch muscles; and 2) the ability of the SNS to control blood flow to low-oxidative type IIB muscle appears to be mediated through postsynaptic α1- and α2-adrenoreceptors on the vascular smooth muscle.

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