title: Central chemoreflex ventilatory responses in humans following passive heat acclimation.
abstract: Since there is temperature dependence of pulmonary ventilation (V˙(E)) in response to the normal modulators (i.e.  [Formula: see text] ,  [Formula: see text] ), it was asked in this study if passive heat acclimation (HA) modifies the human central chemoreflex ventilatory response to CO(2). Nine males performed normothermic- and hyperthermic modified Read re-breathing tests before and after HA. Heat acclimation consisted of 2hday(-1) exposures to 50°C and 20% RH for 10 consecutive days and each exposure elevated rectal temperature to between 38.5 and 39.0°C. Ventilatory recruitment thresholds (VRTs) and central chemosensitivity were assessed before and after HA during normothermia with an oesophageal temperature (T(es)) of ∼37°C and in hyperthermia when T(es) was 38.5-39.0°C. Results showed VRT and central chemosensitivities were unaltered by HA (p≥0.375) and hyperthermia increased pre- (p=0.010) but not post-acclimation (p=0.332) central chemosensitivity. Additionally, during hyperthermia V˙(E) became progressively greater (p=0.027) relative to corresponding normothermic values in the re-breathing tests. In conclusion, the ventilatory response to hyperoxic CO(2) was unaltered by heat Acclimation State.
authors.affiliation: Laboratory for Exercise and Environmental Physiology, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Beaudin
authors.forename: Michael L
authors.initials: ML
authors.lastname: Walsh
authors.forename: Matthew D
authors.initials: MD
authors.lastname: White
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D005334:Fever / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D055815:Young Adult