Increased heat-escape/cold-seeking behavior following hypertonic saline injection in rats.
We examined the effect of hypertonic saline injection on heat-escape/cold-seeking behavior in desalivated rats. Rats were exposed to 40 degrees C heat after normal (154 mM NaCl, control) or hypertonic saline (2,500 mM NaCl) injection (1 ml/100 g body wt). The rats received a 0 degrees C air for 30 s when they entered a specific area in an experimental box. Core temperature (T(c)) surpassed 40 degrees C in both conditions when 0 degrees C air was not available. Hypertonic saline injection produced a lower baseline T(c) than control [36.9 +/- 0.2 and 37.9 +/- 0.2 degrees C (means +/- SE), P < 0.05] and a greater number of 0 degrees C air rewards during the 2-h heat with lower T(c) at the end (48 +/- 1 and 34 +/- 2, 37.6 +/- 0.1, and 37.3 +/- 0.1 degrees C in the control and hypertonic saline injection trial, respectively, P < 0.05, n = 6). However, T(c) was similar (37.7 +/- 0.2 and 37.6 +/- 0.4 degrees C in the control and hypertonic saline injection trial, n = 5) when 0 degrees C air was automatically and intermittently (35 times) given during the heat. Rats augment heat-defense mechanisms in response to osmotic stress by lowering the baseline T(c) and increasing heat-escape/cold-seeking behavior.
Department of Physiology, Osaka University Faculty of Medicine School of Allied Health Sciences, Yamadaoka 1-7, Suita, Osaka 565-0871, Japan. kei@sahs.med.osaka-u.ac.jp
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Nagashima
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Konishi
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D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D001810:Blood Volume; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D004327:Drinking Behavior / Q000502:physiology; D004924:Escape Reaction / Q000187:drug effects / Q000502:physiology*; D006400:Hematocrit; D006706:Homeostasis; D006358:Hot Temperature; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012463:Saliva / Q000502:physiology; D012469:Salivary Glands / Q000502:physiology
D001798:Blood Proteins; D012462:Saline Solution, Hypertonic