Infl uence of Hypothermia on the Activity of LactateDehydrogenase in Blood Serum and Brain Cortex in 14-weekand Adult Laboratory Rats

Overview

Objective:
In the following study, possible protective effect of hypothermia (of various degree) onbrain 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 bloodserum were examined for lactate-dehydrogenase activity (LDH), [E.C. 1.1.1.27]. Three variouslytempered incubation media (38 °C = control values, 30 °C = mild hypothermia, 22 °C = stronghypothermia) 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 conditionwas unchanged as compared with control values. In their brain cortex the hypothermia evokesa signifi cant changes in LDH activity (µkat/l). In adult rats the results are different: no signifi cantchanges in LDH activity in the brain cortex under hypothermic condition were found, but signi-fi cant drop in mentioned enzyme activity in the blood serum was established. Finally: in younganimals the starting LDH activity in the blood serum as well as in the brain cortex was alwayssignifi cantly 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 inyoung rats (as compared with adults) and the different feature of LDH changes under hypothermicconditions are considered and discussed especially with the possibility of protective actionof hypothermia in hypoxic and asphyxic newborns.

Key words:
hypothermia, lactatedehydrogenase, brain cortex, protection