A NEW METHOD FOR CONTINUOUS MEASUREMENT OF REGIONAL CEREBRAL BLOOD-FLOW USING LASER-DOPPLER FLOWMETRY IN A CONSCIOUS RAT

We have developed a new system to continuously measure regional cerebr al blood flow (rCBF) in the cortex of a conscious animal. For this pur pose, we used rats and laser Doppler flowmetry. Under pentobarbital an esthesia, the animal's skull was opened making a small square hole 3 m m x 3 mm in size. A transparent acrylic plate was placed over the hole in the skull. A polyethylene cannula (inner diameter 1.0 mm,length 5. 0 mm) was fixed on the plate as a guide for the laser Doppler flowmete r (LDF) probe (outer diameter 1.0 mm, length 5.5 mm). Both the plate a nd guide cannula were fixed to the skull by dental cement. Every day f or the following two weeks after surgery, the conscious animal was pla ced in a hammock for recording rCBF. A LDF probe was freely attachable to the plate above the cortex via the guide cannula during measuremen t of rCBF. The rats were kept in a hammock with their legs firmly touc hing the floor during measurement of rCBF. It was possible to measure rCBF every day for about two weeks, and rCBF responded consistently to inhalation of 7% CO2 when the responses were expressed as percentages of the prestimulus control rCBF values. This system is recommended fo r the continuous measurement of rCBF in a conscious animal.