TY - JOUR
T1 - Acute hypoosmolality attenuates the suppression of cutaneous vasodilation with increased exercise intensity
AU - Mitono, Hiroyuki
AU - Endoh, Hiroshi
AU - Okazaki, Kazunobu
AU - Ichinose, Takashi
AU - Masuki, Shizue
AU - Takamata, Akira
AU - Nose, Hiroshi
PY - 2005/9
Y1 - 2005/9
N2 - We examined the hypothesis that elevation of the body core temperature threshold for forearm skin vasodilation (THFVC) with increased exercise intensity is partially caused by concomitantly increased plasma osmolality (Posmol). Eight young male subjects, wearing a body suit perfused with warm water to maintain the mean skin temperature at 34 ± 1°C (ranges), performed 20-min cycle-ergometer exercise at 30% peak aerobic power (V̇o2 peak) under isoosmotic conditions (C), and at 65% V̇o2 peak under isoosmotic (HEXIOS) and hypoosmotic (HEXLOs) conditions. In HEXL OS, hypoosmolality was attained by hypotonic saline infusion with DDAVP, a V2 agonist, before exercise. Posmol (mosmol/kgH2O) increased after the start of exercise in both HEX trials (P < 0.01) but not in C. The average Posmol at 5 and 10 min in HEXIOS was higher than in C (P < 0.01), whereas that in HEXLOS was lower than in HEXI OS (P < 0.01). The change in THFVC was proportional to that in Posmol in every subject for three trials. The change in THFVC per unit change in Posmol (ΔTH FVC/ΔPosmol, °C · mosmol-1 · kgH2O-1) was 0.064 ± 0.012 when exercise intensity increased from C to HEXIOS, similar to 0.086 ± 0.020 when Posmol decreased from HEXI OS to HEXLOS (P > 0.1). Moreover, there were no significant differences in plasma volume, heart rate, mean arterial pressure, and plasma lactate concentration around THFVC between HEXIOS and HEXIOS (P > 0.1). Thus the increase in THFVC due to increased exercise intensity was at least partially explained by the concomitantly increased Posmol.
AB - We examined the hypothesis that elevation of the body core temperature threshold for forearm skin vasodilation (THFVC) with increased exercise intensity is partially caused by concomitantly increased plasma osmolality (Posmol). Eight young male subjects, wearing a body suit perfused with warm water to maintain the mean skin temperature at 34 ± 1°C (ranges), performed 20-min cycle-ergometer exercise at 30% peak aerobic power (V̇o2 peak) under isoosmotic conditions (C), and at 65% V̇o2 peak under isoosmotic (HEXIOS) and hypoosmotic (HEXLOs) conditions. In HEXL OS, hypoosmolality was attained by hypotonic saline infusion with DDAVP, a V2 agonist, before exercise. Posmol (mosmol/kgH2O) increased after the start of exercise in both HEX trials (P < 0.01) but not in C. The average Posmol at 5 and 10 min in HEXIOS was higher than in C (P < 0.01), whereas that in HEXLOS was lower than in HEXI OS (P < 0.01). The change in THFVC was proportional to that in Posmol in every subject for three trials. The change in THFVC per unit change in Posmol (ΔTH FVC/ΔPosmol, °C · mosmol-1 · kgH2O-1) was 0.064 ± 0.012 when exercise intensity increased from C to HEXIOS, similar to 0.086 ± 0.020 when Posmol decreased from HEXI OS to HEXLOS (P > 0.1). Moreover, there were no significant differences in plasma volume, heart rate, mean arterial pressure, and plasma lactate concentration around THFVC between HEXIOS and HEXIOS (P > 0.1). Thus the increase in THFVC due to increased exercise intensity was at least partially explained by the concomitantly increased Posmol.
KW - Esophageal temperature
KW - Plasma osmolality
KW - Threshold
UR - http://www.scopus.com/inward/record.url?scp=24044494281&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=24044494281&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.00156.2005
DO - 10.1152/japplphysiol.00156.2005
M3 - Article
C2 - 15845777
AN - SCOPUS:24044494281
VL - 99
SP - 902
EP - 908
JO - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology
JF - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology
SN - 8750-7587
IS - 3
ER -