M. Onitsuka et al., MILD HYPOTHERMIA PROTECTS RAT HIPPOCAMPAL CA1 NEURONS FROM IRREVERSIBLE MEMBRANE DYSFUNCTION INDUCED BY EXPERIMENTAL-ISCHEMIA, Neuroscience research, 30(1), 1998, pp. 1-6
In order to examine the effects of hypothermia on the changes in membr
ane potential induced by experimental ischemia (deprivation of oxygen
and glucose), intracellular recordings were made from single CA1 pyram
idal neurons in slice preparations of rat hippocampus. Application of
ischemic medium caused irreversible changes in membrane potential cons
isting of an initial hyperpolarization, then a slow depolarization and
a rapid depolarization. Al temperatures of 35 degrees C and 37 degree
s C, once the rapid depolarization occurred, readministration of oxyge
n and glucose failed to restore the membrane potential, a state referr
ed to as irreversible membrane dysfunction. When the temperature was l
owered to between 27 degrees C and 33 degrees C, the membrane potentia
l returned to the control resting membrane potential in 75% of the neu
rons. The temperature coefficients (Q(10)) of the latency, the amplitu
de, and the maximal slope of the rapid depolarization were 2.5, 1.4 an
d 2.9, respectively. II is concluded that the critical neuroprotective
temperature in ischemia-induced membrane dysfunction is found to be 3
3 degrees C in single CA1 neurons in vitro. (C) 1998 Elsevier Science
Ireland Ltd. All rights reserved.