Oxygen consumption of hypothalamic tissue slices after varying incubation periods

In order to quantitate possible time-related changes in the viability of rat hypothalamic tissue slices, tissue oxygen consumption was measured after incubation periods ranging from 0-4 hours. There were no significant differences in mean tissue oxygen consumption between the various incubation periods; nor was there any trend indicating that oxygen consumption gradually decreases over time. Moreover, no regional differences were observed among the various rostral hypothalamic slices. One obvious trend, however, was that during the first two hours of each experiment, tissue oxygen consumption decreased briefly and then returned to normal higher levels. The exact occurrence of this transitory decrease varied from experiment to experiment; but the subsequent recovery in oxygen consumption was always complete by two hours of incubation. This initial transient decrease in tissue oxygen consumption may reflect the initial period of electrophysiological inactivity reported in several in vitro studies.