Maturation of Cell Damage After Repetitive Hypoxia—Ischemia in the Rat

Summary

Rats with unilateral carotid ligation were subjected to 10-min periods of hypoxia (10% O₂) with 20-min intervals of normoxia (30% O₂). Development of cytotoxic edema during hypoxia was monitored by the elevation of striatal impedance. After one hypoxic episode the impedance change was always reversible, but after subsequent hypoxic episodes the impedance change progressively became irreversible. Compared to the animals with reversible change of impedance, those with irreversible change had a more elevated striatal Na⁺/K⁺-ratio, and more extensive histological damage as assessed by cellular silver uptake. But even in the animals with reversible impedance change histological damage matured, becoming more extensive from 4h to 24h of survival. Hypothermia (striatal temperature of 28°C) and 48h of food deprivation proved to have a protective effect in delaying the onset of irreversible striatal impedance change.