Development of a transportable incubator for autoradiographic experiments with positron emitter-labeled tracers in...

For autoradiography using positron emitter-labeled tracers in living human brain tissues, samples have to be transported to a positron emission tomography (PET) facility. We have developed a transportable apparatus in which slices are incubated in Krebs-Ringer medium with 95% O(2)/5% CO(2) at 34 degrees C. The incubator comprises a polystyrene foam container, inner chamber, heater, thermostat and battery. The container is sealed and oxygen gas is supplied through a filter (pore size 0.2 microm). The gas is evacuated from the container through the filter, to avoid bacterial contamination. Slices (330 microm) of rat brain were arranged on the nylon net of the inner chamber, and lightly fixed in place by covering them with a fine nylon net stretched over a stainless steel ring. The incubation was carried out at a temperature of 34 degrees C maintained by a heater and thermostat, and the medium was bubbled with 95% O(2)/5% CO(2) from a portable gas cylinder. The temperature of the medium in the container was well controlled (34.0+/-0.5 degrees C) for up to 200 min with no positional differences. In the dynamic autoradiographic experiment, the rate of uptake of [(18)F]2-fluoro-2-deoxy-D-glucose (FDG) in sections preincubated for 45 min in the transportable apparatus was no different from that in the sections kept in the usual incubating apparatus. This apparatus may enable autoradiography using positron emitter-labeled tracers in living human brain tissues.