The eVects of elevating plasma osmolality (P osm ) on thirst ratings was studied in eight dehydrated males during exposure to 4°C. On two occasions, subjects were dehydrated (DH; 3-4% body mass) via 90 min exercise-heat exposure and overnight Xuid restriction (day 1). On a third occasion, subjects were exposed to heat but were given Xuid (EU). On day 2, subjects consumed NaCl (NaCl; 0.1 g NaCl kg ¡1 body mass in 500 ml H 2 O; DH only) or Placebo (P; 500 ml H 2 O; DH and EU). Subjects stood for 30 min at 24°C and for 45 min at 4°C (75 min post-dose). P osm was elevated (P < 0.05) 30 and 75 min after NaCl administration in DH + NaCl versus DH + P and EU + P treatments. Thirst ratings remained elevated (P < 0.05) in the DH + NaCl treatment 30 min after dosing and 45 min at 4°C versus DH + P and EU + P. Attenuation of thirst when dehydrated in the cold can be over-ridden by increasing P osm .

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