Comparing Assessments of Vascular Function via Flow-Mediated Dilation and Rhythmic Handgrip Exercise

Young, otherwise healthy Non-Hispanic Black individuals have been shown to exhibit blunted vascular responsiveness compared to their Non-Hispanic White counterparts, which may be a potential mechanism leading to higher cardiovascular disease risk in this group. Racial differences in vascular function have largely been assessed using flow-mediated dilation (FMD). However, more recent studies have proposed the use of rhythmic handgrip (HG) as an alternative measure of vascular function. PURPOSE: To compare whether rhythmic HG exercise could be an alternative technique to FMD in assessing differences in vascular function between black and white individuals. METHODS: Brachial artery vasodilation was assessed in young healthy black (N = 7; 21 ± 2 years; BMI: 25.5 ± 1.4 kg/m2; mean ± SEM) and white (N = 7; 23 ± 2 years; BMI: 24.0 ± 0.5 kg/m2) men via a standard FMD protocol and rhythmic HG exercise. FMD was assessed by inflating a forearm cuff suprasystolic for 5 min. Rhythmic HG consisted of 3 min HG exercise at 30% of their maximal voluntary contraction (MVC) with a duty cycle of 1-sec contraction/2-sec relaxation. Heart rate (ECG), mean arterial blood pressure (MAP; finger photoplethysmography and automated sphygmomanometer), brachial artery diameter and blood velocity (duplex Doppler ultrasound) were continuously measured during FMD and HG exercise. Brachial artery vasodilation for FMD and rhythmic HG exercise were calculated as a % increase from baseline diameter to peak diameter. RESULTS: Both groups had similar MVCs (black men: 53 ± 1 vs. white men: 54 ± 3 kg; P = 0.80) and resting MAP (black men: 83 ± 2 vs. white men: 85 ± 2 mmHg; P = 0.43). Rhythmic HG dilation (P = 0.72) and FMD (P = 0.43) were not different between groups. Interestingly, white men had greater vasodilation with FMD compared to HG (FMD: 5.76 ± 0.58 vs. HG: 4.13 ± 0.52%; P \u3c 0.01). In contrast, black men had similar vasodilation between FMD and HG (FMD: 4.51 ± 1.01 vs. HG: 4.46 ± 0.89%; P = 0.97). CONCLUSION: These preliminary data suggest that rhythmic HG exercise and FMD provide similar information in the assessment of vascular function between racial groups

Effect of Acute Antioxidant Consumption on Cardiac Baroreflex Sensitivity in Young Healthy Adults

There is an emerging body of evidence in animals indicating that elevated oxidative stress impairs baroreflex sensitivity (BRS) function, however studies in healthy humans have yielded equivocal results. One potential reason for this discrepancy is that previous studies have used individual antioxidant treatments (e.g., Vitamin C only) to investigate the effect of oxidative stress on BRS. Recent studies in healthy humans have demonstrated significant reductions in reactive oxygen species using an antioxidant cocktail (AOC; Vitamin C, Vitamin E, and Co-enzyme Q10) suggesting the effectiveness of this treatment. Whether this AOC induced reduction in oxidative species affects BRS in young, healthy adults remains unknown. PURPOSE: We tested the hypothesis that AOC will improve cardiac BRS in young healthy adults. METHODS: Five young men were studied on two separate days: placebo (sugar pills) and AOC (2000 mg Vitamin C, 150 IU Vitamin E and 100 mg Co-enzyme Q10) performed in random order. Resting heart rate (ECG) and arterial blood pressure (automated sphygmomanometer and finger photoplethysmography) were measured 90 minutes after AOC or placebo (a time period this AOC has been shown to have peak effects on oxidative stress). Spontaneous cardiac BRS was determined for all sequences combined (overall BRS), and also separately for up (increase systolic blood pressure: increase R-R interval) and down (decrease systolic blood pressure: decrease R-R interval) sequences. RESULTS: Systolic blood pressure on AOC day tended to be lower relative to the placebo day (127 ± 4 vs. 131 ± 5; p=0.098). However, no differences in overall cardiac BRS were found between placebo and AOC (18.0 ± 2.7 vs.17.3 ± 2.6 ms/mmHg; p=0.59). Likewise, up sequences (17.02 ± 2.9 vs 14.04 ± 4.0 ms/mmHg; p=0.51) and down sequences (18.0 ± 2.7 placebo vs. 18.0 ± 2.6 ms/mmHg AOC; p=0.98) were not different between conditions. Equal number of sequences were found between the placebo and AOC days. CONCLUSION: These preliminary data suggest that antioxidant treatment does not affect resting cardiac BRS in young, healthy men

Sympathetically-Mediated Cutaneous Vasoconstriction Is Similar Between Non-Hispanic Black and White Individuals

Cardiovascular disease (CVD) prevalence is highest in non-Hispanic Black (BL) individuals compared to any other race. The mechanisms responsible remain incompletely understood and can be impacted by several environmental, psychosocial, and socioeconomic factors. A major contributing factor to elevated CVD risk/prevalence in the BL population is altered vascular function, which could be attributed to an exaggerated vasoconstrictor response to efferent sympathetic activity (i.e., sympathetic vascular transduction). Previous data from our group demonstrates heightened sympathetic vascular transduction in the peripheral vasculature of BL males. However, whether sympathetically-mediated vasoconstriction is exaggerated in the cutaneous circulation of BL individuals remains unknown. PURPOSE: This study tested the hypothesis that BL individuals exhibit exaggerated vasoconstriction to intra-dermal infusions of the α-adrenoreceptor agonist norepinephrine (NE) relative to White (WH) individuals. METHODS: In this study, young, healthy college-aged BL (n=13; 6 females) and WH (n=10; 4 females) individuals participated. Participants were instrumented with an intradermal microdialysis membrane in the dorsal forearm. Red blood cell flux was continuously assessed via laser Doppler flowmetry before (baseline) and during incrementally stronger infusions of NE (10-8 M – 10-2 M; 6 min/dose). Data were analyzed as a relative (i.e., percent) reduction in cutaneous vascular conductance (CVC: flux/MAP) compared to the pre-infusion baseline. RESULTS: NE caused a dose-dependent reduction in CVC in both groups (P\u3c0.001). There was no difference between the BL and WH individuals (P=0.37) nor was there a race x dose interaction (P=0.84). Similarly, when the data were separated by sex there was no difference between BL and WH males (P=0.56) or females (P=0.26). CONCLUSION: Vasoconstrictor responsiveness to α-adrenoreceptor activation was similar between BL and WH individuals. These data suggest that the cutaneous circulation may exhibit divergent sympathically-mediated vasoconstrictor responsiveness relative to other peripheral vascular beds in BL individuals

Ten rules for leveraging LLMs for getting grants.

Proposal development timeline to illustrate at what point in your grant writing journey to incorporate each rule. Light bulb and coal icons used in Fig 1 were adapted from https://www.svgrepo.com/svg/524676/lightbulb-minimalistic and https://www.svgrepo.com/svg/398225/rock, respectively.</p

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Ten simple rules to leverage large language models for getting grants</p

Acute High Dietary Phosphate Consumption Impairs Macrovascular, But Not Microvascular Function in Young, Healthy Men

Chronic consumption of inorganic phosphate (Pi) is associated with an increased risk of cardiovascular disease in the general population. Importantly, with the growing abundance of processed foods, dietary intake of Pi in the United States has doubled the daily-recommended amount. However, the influence of acute consumption of high Pi on the cardiovascular system is not clearly understood, with equivocal results reported. Shuto et al. demonstrated that acute consumption of high Pi results in an impairment of endothelial function in healthy subjects, whereas a recent study by Levac et al. has refuted this finding. Moreover, these studies have only investigated conduit artery endothelial function, however microvascular responses, assessed by reactive hyperemia, have not been previously examined. PURPOSE: We tested the hypothesis that acute high Pi consumption impairs both macrovascular and microvascular function in young, healthy men. METHODS: On separate days, subjects ingested either Monosodium Phosphate (NaPi) containing 2,000 mg of phosphorus and 1,520 mg of sodium (N= 13; 23 ± 1 yrs; mean ± SEM) or Sodium Chloride (NaCl) control containing 1,520 mg of sodium (N=5; 23 ± 2 yrs). Blood samples were collected at baseline, 60 min and 120 min post- NaPi and NaCl consumption to measure serum phosphate. Flow-mediated dilation (FMD) was used to assess macrovascular function, and reactive hyperemia was used to assess microvascular function at baseline, and 60 min post. RESULTS: Serum phosphate was significantly elevated at 60 min and remained elevated at 120 min post- NaPi consumption, but did not change with NaCl. Importantly, FMD was significantly attenuated at 60 min post- NaPi consumption, (pre, 5.4 ± 0.6%; post, 3.1 ± 0.5%; PP=0.97). In contrast, reactive hyperemia remained unaffected by both NaPi (pre, 7633.26 ± 657.12 AU; post, 7357.31 ± 958.61 AU; P=0.69) and NaCl conditions, (P=0.96) indicating preserved microvascular function. CONCLUSION: Our findings indicate that acute high NaPi impairs peripheral macrovascular, but not microvascular, function in young healthy men. These data suggest that conduit artery endothelial function may be more susceptible than the microvasculature to acute consumption of high NaPi