Influence of uncomplicated, controlled hypertension on local heat-induced vasodilation in nonglabrous skin across the body

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2022-04, Vol.322 (4), p.R326-R335
• Main Authors: McGarr, Gregory W, King, Kelli E, Akerman, Ashley P, Fujii, Naoto, Ruzicka, Marcel, Kenny, Glen P
• Format: Article
• Language: English
• Subjects: Abdomen; Adult; Arginine; Enzyme Inhibitors - pharmacology; Equivalence; Female; Females; Forearm; Heating; Hot Temperature; Humans; Hypertension; Male; Microdialysis; NG-Nitroarginine methyl ester; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitric Oxide - metabolism; Plateaus; Regional Blood Flow - physiology; Skin; Skin - blood supply; Skin temperature; Thigh; Vasodilation
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00282.2021

The objective of this study was to examine pooled effects of hypertension on nitric oxide (NO)-dependent vasodilation during local heating across multiple nonglabrous skin regions, and explore regional differences. Responses were compared between 14 participants with uncomplicated hypertension controlled with medication (7 females, 61 ± 6 yr) and 14 age-matched nonhypertensive controls (6 females; 60 ± 5 yr). Cutaneous vascular conductance, normalized to maximum vasodilation (%CVC ), was assessed at the upper chest, abdomen, dorsal forearm, thigh, and lateral calf during local heating. Across all regions, local skin temperatures were simultaneously increased from 33°C to 42°C (1°C·10 s ) and held until a stable heating plateau was achieved (∼40 min), followed by continuous infusion of 20 mM of -nitro-l-arginine methyl ester (l-NAME; ∼40 min) at all sites until a stable l-NAME plateau was achieved. The difference between heating and l-NAME plateaus was defined as the NO-contribution. Statistical equivalence for each heating phase was determined based on equivalence bounds of ±10%CVC for between-group differences. Pooled (all-regions) %CVC responses were equivalent for baseline (two one-sided tests; < 0.001), heating plateau ( = 0.002), l-NAME plateau ( = 0.028), and NO-contribution ( = 0.003). For individual regions, responses were equivalent at baseline for the abdomen, thigh, and calf, the heating plateau for the thigh, and the l-NAME plateau for the calf (all < 0.05). Conversely, the calf heating plateau was lower in the hypertension group ( test; < 0.05). Local heat-induced cutaneous vasodilation was statistically equivalent between individuals with uncomplicated, controlled hypertension, and nonhypertensive age-matched adults when pooled across multiple skin sites. Conversely, individual between-region comparisons were generally too variable to permit definitive conclusions.