Dietary NO 3 - does not enhance endothelial dependent cutaneous vascular conductance in older women.

Prior work has yet to determine whether the reduction of dietary nitrate (NO ₃ ^- ) to NO, via the enterosalivary pathway, may modify cutaneous vascular conductance (CVC) responses to local heating in older women. Changes occurring with the transition to menopause related to hormonal flux, increased adiposity, and/or decreased physical activity may further compound the negative influence of aging on nitric oxide (NO)-dependent CVC. Herein, we characterized changes in NO-dependent CVC following acute ingestion of 140 mL of NO ₃ ^- -rich beetroot juice in 24 older women (age: 65 ± 5 y, BMI: 31.2 ± 3.7 kg/m ² ). Red blood cell (RBC) flux was measured continuously via laser-Doppler flowmetry on the dorsal aspect of the forearm during local skin heating to 39 °C/44 °C before and 3 h after NO ₃ ^- ingestion. NO-dependent changes in CVC were calculated as RBC flux/mean arterial blood pressure at 39 °C and normalized as a proportion of maximal CVC at 44 °C (%CVCmax). Changes (Δ) in fractional exhaled NO (FeNO) following NO ₃ ^- ingestion were used an index of NO bioavailability. Despite increased FeNO (+81 ± 70 %, P < 0.001), %CVCmax at 39 °C was reduced (-16 ± 10 %, P < 0.001) following NO ₃ ^- ingestion. A greater reduction in %CVCmax was weakly to moderately associated with higher body fat% (r = 0.45 [0.05-0.72], P = 0.029), central adiposity% (r = 0.50 [0.13-0.75], P = 0.012), neutrophil% (r = 0.42 [0.02-0.70], P = 0.041), and higher neutrophil to lymphocyte ratio (r = 0.49 [0.11-0.75], P = 0.016). These findings demonstrate a single dose of dietary NO ₃ ^- does not promote CVC responses to local heating in sedentary older women with overweight and obesity. Correlation with multiple biomarkers suggest systemic inflammation may be involved.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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