title: Can intradermal administration of angiotensin II influence human heat loss responses during whole body heat stress?
abstract: It is unclear if angiotensin II, which can increase the production of reactive oxygen species (oxidative stress), modulates heat loss responses of cutaneous blood flow and sweating. We tested the hypothesis that angiotensin II-induced increases in oxidative stress impair cutaneous perfusion and sweating during rest and exercise in the heat. Eleven young (24 ± 4 yr) healthy adults performed two 30-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C). The first and second exercises were followed by a 20- and 40-min recovery. Four microdialysis fibers were placed in the forearm skin for continuous administration of either: 1) lactated Ringer (control), 2) 10 μM angiotensin II, 3) 10 mM ascorbate (an antioxidant), or 4) a combination of 10 μM angiotensin II + 10 mM ascorbate. Cutaneous vascular conductance (CVC; laser-Doppler perfusion units/mean arterial pressure) and sweating (ventilated capsule) were evaluated at each skin site. Compared with control, angiotensin II reduced both CVC and sweating at baseline resting and during each recovery in the heat (all P < 0.05). However, during both exercise bouts, there were no differences in CVC or sweating between the treatment sites (all P > 0.05). When ascorbate was coinfused with angiotensin II, the effect of angiotensin II on sweating was abolished (all P > 0.05); however, its effect on CVC at baseline resting and during each recovery remained intact (all P < 0.05). We show angiotensin II impairs cutaneous perfusion independent of oxidative stress, while it impairs sweating through increasing oxidative stress during exposure to an ambient heat stress before and following exercise.
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Naoto
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Meade
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Paull
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: McGinn
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Imane
authors.initials: I
authors.lastname: Foudil-bey
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Pegah
authors.initials: P
authors.lastname: Akbari
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada gkenny@uottawa.ca.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000279:Administration, Cutaneous; D000804:Angiotensin II / Q000008:administration & dosage*; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D005542:Forearm / Q000098:blood supply / Q000502:physiology; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D017551:Microdialysis / Q000379:methods; D018384:Oxidative Stress / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012146:Rest / Q000502:physiology; D012867:Skin / Q000098:blood supply / Q000187:drug effects; D013546:Sweating / Q000187:drug effects / Q000502:physiology
chemical_list: D000804:Angiotensin II
keywords: AT1 receptor; microcirculation; reactive oxygen species; renin-angiotensin-aldosterone system; sudomotor