Accession Number:

ADA248464

Title:

Cumulative Effect of Repeated Brief Cerebral Ischemia

Descriptive Note:

Final rept. 15 Jun 1990-14 Dec 1991

Corporate Author:

ALABAMA UNIV IN BIRMINGHAM SCHOOL OF MEDICINE

Personal Author(s):

Report Date:

1991-12-14

Pagination or Media Count:

22.0

Abstract:

We have investigated the problem of Gz-induced blackout in an animal model in which controlled brief global cerebral ischemia is produced repeatedly at short intervals. The objective was to determine if this results in cumulative impairment of brain metabolism and electrical function and if so to identify the mechanisms involved. Our initial hypothesis was that accumulation of lactate may be an important element in this process. Rats were prepared for experiment under halothane anesthesia with tracheostomy, ligation of both subclavian arteries, cannulation of one femoral artery, and of one common carotid artery in cephalad direction. Both external carotid arteries were ligated. Both mouth and rectal temperatures were monitored with thermocouples and mouth temperature was maintained at 37.0 or - 0.5 degrees Celsius. A balloon in cuff was placed around the remaining carotid artery. The rat was placed within the spectrometer magnet operating at 4.7 Telsa for lactate and phosphorous. Repeated brief episodes of global brain ischemia were made by temporary inflation of the carotid balloon while MR proton spectra are being acquired serially at intervals of 30 seconds using a 1 cm surface coil. We report results using a newly constructed doubly tuned probe enabling interleaved acquisition of 31 P high energy phosphates and pH and 1 H lactate and amino acids. Different durations of ischemia and intervals between them were tested to determine thresholds for development of EEG impairment, tissue acidosis, high energy phosphate depletion, and lactate accumulation.

Subject Categories:

  • Medicine and Medical Research

Distribution Statement:

APPROVED FOR PUBLIC RELEASE