RESUMO
The authors compared the changes of morphology, blood brain barrier alteration, pathology, arterial blood lactate content and cerebrospinal fluid lactate content between an intermittent brain retraction group and a continuous brain retraction group in 56 mongrel cats. The results were as follows ; 1) Microscopically, hemorrhages were punctate in 15 cases among 25 cases in the intermittent retraction group. However, there were multiple or large hemorrhages in 13 cases among the 25 cases in the continuous brain retraction group. 2) All cases of the intermittent retraction group showed 0~25% Evans blue staining of the coronal section crossing the retraction site. However, 8 cases among the 25 cases of the continuous retraction group showed 51~75% Evans blue staining and 4 cases of this group showed 76~100% staining. 3) With photomicroscopy, the authors noted small hemorrhage and cellular swelling in the intermittent retraction group instead of pyknosis, hemorrhagic necrosis, vacuolation in the continuous retraction group. 4) The change of arterial blood lactate content was from 1.22+/-0.24mmol/L at preretraction time to 1.42+/-0.26mmol/L at 90 minutes after release of retractor in the intermittent retraction group(p0.05). In the continuous retraction group, this author noted change in the lactate content from 1.37+/-0.28mmol/L to 2.11+/-0.52mmol/L for the same time as described above(p<0.01). From the above results, the superiority of the intermittent brain retraction was demonstrated as compared with the continuous brain retraction. Also the possible utilization of this experimental method was discussed for other wxperimental studies on ischemia.