CYTOCHROME-OXIDASE IS DECREASED IN PIGLET HIPPOCAMPUS FOLLOWING HYPOXIA-ISCHEMIA

We assessed cytochrome oxidase (CytOx) staining in sham-operated contr ol piglets and in piglets subjected to 30 minutes of cerebral hypoxia- ischemia (H-I) plus 4 hours of reperfusion (REP). The I-day-old piglet s were sedated, anesthetized, and ventilated. Cerebral blood flows (CB Fs) were quantitated using microspheres. H-I was induced by a combinat ion of phlebotomy and cervical tourniquet; the brain was reperfused fo r four hours after 30 minutes of H-I. CBF was reduced during ischemia in experimental animals from 42+13 to 12+5 ml/min/100g. CytOx staining of hippocampal sections from 3 control and 3 experimental animals was compared. The staining of the stratum pyramidale neurons of the same portion of the CA1 sector in a single high power field was assessed in a blinded fashion in 4 corresponding sections from each animal, and g raded from 0=no staining to 3=heavy staining. The results were compare d using one-way analysis of variance. Cells with grade 3 staining were significantly more numerous in controls compared to H-I/REP animals ( p=0.03). There were significantly more cells with no CytOx staining in the experimental animals (p=0.01). These findings suggest that CytOx staining in newborn piglet CA1 is a reliable method of assessing cell dysfunction after H-I.