[The effect of posthypoxic hypothermia for lactate dehydrogenase activity in brain cortex and blood serum of 14-days-old rats]. / Vliv a význam hypoxie a následné hypotermie na aktivitu laktátdehydrogenázy v mozkové kure a v krevním séru u 14denních laboratorních potkanu.

OBJECTIVE: The effect of various degrees of hypobaric hypoxia and consequent hypothermia on lactate dehydrogenase (E.C.1.1.1.27) activity in blood serum and brain cortex in 14 day-old rats was investigated. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague. METHODS: 14 day-old rats (Wistar of our own breed) were exposed to mild hypobaric hypoxia (corresponding to altitude of 7000 m, pO2 = 8.6 kPa, BP = 41.2 kPa, lasting 20 min) or strong hypobaric hypoxia (corresponding to altitude of 9000 m, pO2 = 6.4 kPa, BP = 30.7 kPa, lasting 30 min). Just after hypoxic stress the animals were killed by decapitation and on cooled block the grey cortical matter was removed. Blood serum samples as well as brain cortex homogenates were immediately incubated in three variously tempered media (38 degrees Celsius = control values, 30 degrees Celsius and 22 degrees Celsius = hypothermic conditions). The incubation was over (30 min.), and the lactate dehydrogenase (LDH) activity was followed using the Lachema test. RESULTS: The LDH activity was influenced by mild hypobaric hypoxia (7000 m) neither in blood serum nor in brain cortex. Also the values of LDH activities registered in normo or in hypothermic conditions were not different as compared with control values. The strong hypoxia (9000 m) evokes in brain cortex homogenates simultaneously with normothermia and posthypoxic hypothermia (30 degrees Celsius) significant increase of LDH activity. In blood serum the strong hypoxia increased the LDH activity; in subsequent hypothermic condition (22 degrees Celsius) the LDH activity was more lowered. CONCLUSION: The LDH activity in brain cortex as well as in blood serum of young rats (Wistar) seems to be resistent to mild hypoxia (7000 m) as well to hypothermic conditions. The strong hypoxia (9000 m) evokes quite different responses: in brain cortex the LDH activities in hypothermic conditions are higher, in blood serum lower as compared with control values (14 day-old rats stressed by hypoxia only). In control measurements the lowering temperature decreases the mentioned enzyme activity in brain cortex; in blood serum no significant differences could be found.

[Effect of hypothermia on lactate dehydrogenase activity in blood and the cerebral cortex in 14-day-old and adult laboratory rats]. / Vliv hypotermie na aktivitu laktátdehydrogenázy v krevním séru a v mozkové kure u 14denních a dospelých laboratorních potkanu.

OBJECTIVE: In the following study, possible protective effect of hypothermia (of various degree) on brain cortex metabolic activity in very young animals and adult rats was examined. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague, Czech Republic. METHODS: Homogenates of brain cortex of 14-day-old and adult rats and simultaneously blood serum were examined for lactate-dehydrogenase activity (LDH), [E.C. 1.1.1.27]. Three variously tempered incubation media (38 degrees C = control values, 30 degrees C = mild hypothermia, 22 degrees C = strong hypothermia) were checked. Also the adult rats (90-120 days) were examined (in the same arrangement). RESULTS: The LDH activity in the blood serum of 14-day-old rats under hypothermic condition was unchanged as compared with control values. In their brain cortex the hypothermia evokes a significant changes in LDH activity (mukat/l). In adult rats the results are different: no significant changes in LDH activity in the brain cortex under hypothermic condition were found, but significant drop in mentioned enzyme activity in the blood serum was established. Finally: in young animals the starting LDH activity in the blood serum as well as in the brain cortex was always significantly higher as compared with values found in adult animals. CONCLUSION: The starting higher LDH activity in the blood serum as well as in the brain cortex in young rats (as compared with adults) and the different feature of LDH changes under hypothermic conditions are considered and discussed especially with the possibility of protective action of hypothermia in hypoxic and asphyxic newborns.

[Gestational diabetes--a model trial. The effect of alloxan diabetes on the spectrum of fatty acids in the blood, liver and brain in laboratory rats]. / Gestacní diabetes--modelová studie. (Vliv aloxanového diabetu na spektrum mastných kyselin v krevním séru, v játrech a v mozku u laboratorního potkana).

In alloxan-induced diabetic rats (Wistar, females, age 3-4 months of postnatal life) the large spectrum of fatty acids in blood serum, brain cortex, medulla oblongata and liver was studied. The fatty acids, using gas chromatography, were detected as methyl esters and the methods were published previously (Smídová and al. 1994). Alloxan (Merck) administered i.p., 140 mg/kg body weight, caused immediately elevation (three times) of blood sugar levels. On the 13th day the rats were killed. The results are as follows: a) In blood serum alloxan diabetes of cca two weeks duration caused a significantly increased participation of saturated FA and decreased participation of both polyunsaturated FA (n-3 and n-6). b) In brain cortex no differences between controls and diabetic rats in the indicated groups of FA were found. c) In the medulla oblongata an increased participation of polyunsaturated fatty acids n-6 was established. d) In hepatic tissue the increased participation of saturated FA as well as a decreased participation of FA n-6 was described. Analysing the main groups of FA we found especially in n-3 and n-6 FA several significant changes in single FA (a smaller pool of arachidonic acid in blood serum as well as in liver, decreased participation of docosahexaenoic acid in the brain cortex, etc.). The purpose and possible consequences of such changes are discussed.