[The effect of hypothermia on the rat radioresistance].
The cooling of Wistar rats up to 15-19 degrees C under a condition hypoxia-hypercapnia increased the radioresistance with a dose reduction factor (DRF) of 1.4. To elucidate the mechanisms of hypothermia radioprotective effect was evaluated the functional state of rat neocortex using a electroencephalogram (EEG) as well as was studied the lipid composition of neocortex under the conditions of both normothermia and hypothermia. At 19-20 degrees C the activity within a wide range of frequencies in EEG was suppressed; the nonregular slow waves were recorded against a background of "silence". The reduction of EEG spectrum with increasing temperature began with the low frequencies. At 26-28 egresC the contribution of theta-rhythm (an indicator of brain activity level) in EEG reaches the normothermia value, from this point the rat brain starts to functionate as a whole system. At normothermia the similarity of neocortex lipid composition in nonhibernators (rats) and hibernators (ground squirrels) mammalians was noted. The difference is only in a higher content of phosphatidylinositol in rats. Rats falling into hypothermia state as well as ground squirrels into torpor is followed by a decrease of cholesterol content and the absence of significant changes of the phospholipid composition in neocortex tissues.
Ignat'ev
D A
DA
Fialkovskaia
L A
LA
Perepelkina
N I
NI
Markevich
L N
LN
Kraev
I V
IV
Kolomiĭtseva
I K
IK
D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography; D006339:Heart Rate; D006605:Hibernation; D007036:Hypothermia, Induced; D008055:Lipids / Q000032:analysis; D008297:Male; D019579:Neocortex / Q000378:metabolism; D011836:Radiation Tolerance / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013826:Theta Rhythm; D014965:X-Rays
D008055:Lipids; D002784:Cholesterol