A new sample-processing unit for the fluorescent microsphere method

The use of fluorescent-labeled microspheres (FM) for measurement of regiona l blood flow is an attractive alternative to the use of radioactive-labeled microspheres. In the FM method the FM have to be completely recovered from the tissue samples in a time- and labor-intensive process. For this reason , a considerable loss of FM is possible. The aim Of this study was to devel op a filtration device that allows the tissue sample to remain in a single container throughout the procedure to make the process easier and to avoid the loss of FM. The core of the sample-processing unit (SPU) is a single-tu be filtration device with a polyamide wire mesh. The protocol for processin g tissue from different organs (heart, kidney, liver, spleen, intestine, mu scle, bone, lung, brain) was modified and thus shortened significantly. Fur thermore, the SPU allows direct filtration of the blood reference sample wi thout previous digestion. Different experiments showed that the SPU in comb ination with the new protocol excludes the loss of 15-mu m FM. The modifica tions of the whole procedure render it faster and highly standardized.