AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 3 600-R609, Copyright © 1984 by American Physiological Society
Evaluation of a system for serial biopsy of cerebral cortical tissue in an awake goat
D. A. Pelligrino, D. J. Miletich, R. F. Albrecht, D. Visintine, R. Ripper, G. Dominguez and J. Kuse
No techniques to date have been developed that allow investigators to
obtain serial, rapidly frozen brain tissue samples in unanesthetized
animals. The design and methods for implantation of cranial windows in
goats are described in detail. The cranial window allows one direct and
repeated access to the cerebral cortical surface. With each window, a
parietal cortical area of 7.9 cm2 (minus the dura) is available for biopsy.
Serial tissue samples are obtained using a suction-freezing system. Samples
(100-250 mg) are frozen in less than 1 s. Up to six samples can be taken
from each site. Goats were studied over a period of 2-5 days. No signs of
sampling or immobilization stress were present as evidenced by a relatively
constant level of arterial catecholamines and CO2 partial pressure (PCO2).
Local cerebral blood flow (CBF) in the tissue under the window was of the
same magnitude as that in other cerebral cortical regions and was
unaffected by serial sampling. Levels of labile phosphates and of some
glycolytic and tricarboxylic acid cycle-associated intermediates were
minimally influenced by serial sampling. Greater variability in metabolite
levels was seen for biopsies taken 2-5 days apart than for biopsies taken
at 1- to 2-min intervals. However, variations within animals were less than
variations among animals. This was especially true for acutely biopsied
samples. The described methods provide a model for studies of cerebral
metabolism in unstressed goats where anesthetic influences are avoided and
where each animal can be utilized as its own control.
