Cytochrome reduction induced by increase in extracellular potassium and by electrical stimulation in isolated perifused neurohypophysis of guinea pig under mild hypoxic conditions

Correlation between adaptability to hypoxia and thickness of guinea pig olfactory cortical slice in vitro

Adult guinea pig olfactory cortical slices were used to assess the ability to adapt to hypoxic conditions after brief and repeated exposure to nitrogen gas. This adaptability differed according to slice thickness. The field potential recorded from thin slices (300-360 microns) decreased in amplitude to only 80% of the control value when the slice preparation was repeatedly exposed to nitrogen gas. The potential gained from the medium slices (420-500 microns) showed a stepwise increase in amplitude after repeated exposure to short-term hypoxia. The potential obtained from the thick slices (500-560 microns) decreased prominently in amplitude and disappeared after the first nitrogen gas exposure and the amplitude recovered to only half of the control value under renormoxic conditions and subsequent hypoxic conditions resulted in a small amplitude increase of hypoxia tolerance potential. It is proposed that the energy to support the production of hypoxic tolerance potential is supplied by glycolytic processes because the redox state levels of cytochromes measured by using an organ spectrophotometer were observed to be the same under hypoxia-renormoxia conditions.