Role of cyclooxygenase in the vascular response to locally delivered acetylcholine in Caucasian and African descent individuals

Maley, Matthew J.; House, James R.; Tipton, Michael J.; Eglin, Clare

doi:10.1016/j.mvr.2017.01.005

Cited by 7 publications

(13 citation statements)

References 55 publications

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“…Average skin blood flow in response to iontophoresis of ACh was calculated over the final 20 seconds of the interval between successive pulses and between 40 to 60 seconds after the final pulse (Maley et al, 2017). These responses were expressed as absolute CVC as baseline CVC did not differ between conditions for any site.…”

Section: Measurementsmentioning

confidence: 99%

Effects of dietary nitrate supplementation on the response to extremity cooling and endothelial function in individuals with cold sensitivity. A double blind, placebo controlled, crossover, randomised control trial

et al. 2017

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Individuals with cold sensitivity have low peripheral skin blood flow and skin temperature possibly due to reduced nitric oxide (NO•) bioavailability. Beetroot has a high concentration of inorganic nitrate and may increase NO-mediated vasodilation. Using a placebo-controlled, double blind, randomised, crossover design, this study tested the hypotheses that acute beetroot supplementation would increase the rate of cutaneous rewarming following a local cold challenge and augment endothelium-dependent vasodilation in cold sensitive individuals. Thirteen cold sensitive participants completed foot and hand cooling (separately, in 15 °C water for 2 min) with spontaneous rewarming in 30 °C air whilst skin temperature and cutaneous vascular conductance (CVC) were measured (Baseline). On two further separate visits, participants consumed 140 ml of either concentrated beetroot juice (nitrate supplementation) or nitrate-depleted beetroot juice (Placebo) 90 min before resting seated blood pressure was measured. Endothelial function was assessed by measuring CVC at the forearm, finger and foot during iontophoresis of 1% w/v acetylcholine followed by foot and hand cooling as for Baseline. Plasma nitrite concentrations significantly increased in nitrate supplementation compared to Placebo and Baseline (502 ± 246 nmol L; 73 ± 45 nmol L; 74 ± 49 nmol L respectively; n = 11; P < 0.001). Resting blood pressure and the response to foot and hand cooling did not differ between conditions (all P > 0.05). Nitrate supplementation did not alter endothelial function in the forearm, finger or foot (all P > 0.05) compared to Placebo. Despite a physiologically meaningful rise in plasma nitrite concentrations, acute nitrate supplementation does not alter extremity rewarming, endothelial function or blood pressure in individuals with cold sensitivity.

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Section: Measurementsmentioning

confidence: 99%

Effects of dietary nitrate supplementation on the response to extremity cooling and endothelial function in individuals with cold sensitivity. A double blind, placebo controlled, crossover, randomised control trial

et al. 2017

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“…Using this new approach, we demonstrated that ethnicity per se does not influence NO-dependent cutaneous vasodilatation or sweating in healthy young men during rest, moderate-intensity exercise and recovery in dry heat. That said, differences in cutaneous vasodilator responsiveness between men of black-African and Caucasian descent have been observed in other experimental conditions Kim et al, 2018;Maley et al, 2017). This indicates that ethnicity should remain an important consideration when designing mechanistic studies to evaluate local thermoeffector control, depending on the modulator being investigated and the experimental conditions being used.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, black-African descendants demonstrate reduced forearm (Ozkor et al, 2014) c 2019 The Authors. Experimental Physiology c 2019 The Physiological Society and local cutaneous (Maley, House, Tipton, & Eglin, 2017) vasodilator responsiveness relative to Caucasians. Furthermore, sweat gland activation during passive heat exposure is lower in men of black-African descent than in Caucasians (Kawahata & Adams, 1961) albeit, relative increases in sweat output in response to phamacological stimulation have also been reported for men of black-African descent (Gibson & Shelley, 1948).…”

Section: Introductionmentioning

confidence: 99%

Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black‐African and Caucasian descent during exercise in the heat

Muia

McGarr

Schmidt

et al. 2019

Experimental Physiology

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New Findings What is the central question of this study?Nitric oxide modulates cutaneous vasodilatation and sweating during exercise‐induced heat stress in young men. However, it remains uncertain whether these effects are reduced in black‐African descendants, who commonly demonstrate reduced nitric oxide bioavailability. Therefore, we assessed whether black‐African descendants display reduced nitric oxide‐dependent cutaneous vasodilatation and sweating compared with Caucasians in these conditions. What is the main finding and its importance?Nitric oxide‐dependent cutaneous vasodilatation and sweating were similar between groups, indicating that reduced nitric oxide bioavailability in black‐African descendants does not attenuate these heat‐loss responses during an exercise‐induced heat stress. Abstract Men of black‐African descent are at an increased risk of heat‐related illness relative to their Caucasian counterparts. This might be attributable, in part, to reduced cutaneous nitric oxide (NO) bioavailability in this population, which might alter local cutaneous vasodilatation and sweating. To evaluate this, we compared these heat‐loss responses in young men (18–30 years of age) of black‐African (n = 10) and Caucasian (n = 10) descent during rest, exercise and recovery in the heat. Participants were matched for physical characteristics and fitness, and they were all born and raised in the same temperate environment (i.e. Canada; second generation and higher). Both groups rested for 10 min and then performed 50 min of moderate‐intensity exercise at 200 W m−2, followed by 30 min of recovery in hot, dry heat (35°C, 20% relative humidity). Local cutaneous vascular conductance (CVC%max) and sweat rate (SR) were measured at two forearm skin sites treated with either lactated Ringer solution (control) or 10 mm NG‐nitro‐l‐arginine methyl ester (l‐NAME, a nitric oxide (NO) synthase inhibitor). l‐NAME significantly reduced CVC%max throughout rest, exercise and recovery in both groups (both P < 0.001). However, there were no significant main effects for the contribution of NO to CVC%max between groups (all P > 0.500). l‐NAME significantly reduced local SR in both groups (both P < 0.050). The contribution of NO to SR was similar between groups such that l‐NAME reduced SR relative to control at 40 and 50 min into exercise (both P < 0.05). We demonstrate that ethnicity per se does not influence NO‐dependent cutaneous vasodilatation and sweating in healthy young men of black‐African and Caucasian descent during exercise in dry heat.

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“…For a number of years, investigators conducting studies on human thermoregulatory function have often selected participants from only one ethnic group to minimize the confounding influence of ethnicity (Glickman-Weiss, Nelson, Hearon, & Day, 1997;Stephens & Hoag, 1981). This might remain an important consideration for more mechanistic research directed at the evaluation of thermoeffector control, especially given that there is evidence of ethnicity-related differences in the control of cutaneous blood flow (Maley, House, Tipton, & Eglin, 2017b, 2017a. However,…”

Section: Discussionmentioning

confidence: 99%

Whole‐body heat exchange in black‐African and Caucasian men during exercise eliciting matched heat‐loss requirements in dry heat

Muia

Notley

Saci

et al. 2019

Experimental Physiology

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Ethnicity has long been thought to modulate thermoregulatory function; however, an evaluation of whole-body heat exchange in men of black-African descent and Caucasian men (white-European descendants), born and raised in the same climate, during exercise eliciting matched heat-loss requirements remained unavailable. We therefore used direct calorimetry to assess whole-body total heat loss (evaporative plus dry heat exchange) in young (18-30 years of age), second-generation (or higher) black-African (n = 11) and Caucasian (n = 11) men. Participants performed three 30 min bouts of semi-recumbent cycling at fixed metabolic heat productions (and therefore matched heat-loss requirements between groups) of 200 (light), 250 (moderate) and 300 W m −2 (vigorous), each followed by 15 min recovery, in dry heat (40 • C, ∼13% relative humidity). Across all exercise bouts, dry (P = 0.435) and evaporative (P = 0.600) heat exchange did not differ significantly between groups. As such, total heat loss during light, moderate and vigorous exercise was similar between groups (P = 0.777), averaging [mean (SD)] 177 (10), 217 (13) and 244 (20) W m −2 in black-African men and 172 (13), 212 (17) and 244 (17) W m −2 in Caucasian men. Accordingly, body heat storage across all exercise bouts (summation of metabolic heat production and total heat loss) was also similar between the black-African [568 (142) kJ] and Caucasian groups [623 (124) kJ; P = 0.356]. We demonstrated that, when assessed in young, second-generation (or higher) black-African and Caucasian men during exercise eliciting matched heat-loss requirements in dry heat, ethnicity did not significantly modulate whole-body dry and evaporative heat exchange or the resulting changes in total heat loss and body heat storage.

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Role of cyclooxygenase in the vascular response to locally delivered acetylcholine in Caucasian and African descent individuals

Abstract: CAU have a greater endothelial reactivity than AFD in both foot and finger skin sites irrespective of COXib. It is concluded that the lower ACh-induced vasodilatation in AFD is not due to a compromised COX pathway.

Cited by 7 publications

References 55 publications

Effects of dietary nitrate supplementation on the response to extremity cooling and endothelial function in individuals with cold sensitivity. A double blind, placebo controlled, crossover, randomised control trial

Effects of dietary nitrate supplementation on the response to extremity cooling and endothelial function in individuals with cold sensitivity. A double blind, placebo controlled, crossover, randomised control trial

Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black‐African and Caucasian descent during exercise in the heat

Whole‐body heat exchange in black‐African and Caucasian men during exercise eliciting matched heat‐loss requirements in dry heat

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