Measurement of erythrocyte deformability and methodological adaptation for small-animal microsurgical models

Measuring erythrocyte deformability with bulk filtrometers is common, but there are problems with standardization and sample quantity in small laboratory animals. In this study, blood was drawn from mice, rats, and dogs, and then erythrocyte suspensions at 1-5% hematocrit were prepared. Bulk filtrometers with a 5- or 3-microm pore-diameter filter were used to determine the initial relative filtration rate (IRFR) and relative cell transit time (RCTT). Hematological composition was also tested. In all species, the highest IRFR values occurred at 1% hematocrit, and the lowest values at 5%. In mice and rats, RCTT values were lowest at 1% and highest at 5% using a 5-microm filter, whereas in dogs, RCTT was elevated at 1-2%. Using a 3-microm filter, each species showed the same phenomena under 3%. RCTT values may become distorted above a certain cell-size/pore-size ratio. In mice and rats, 1% suspension is applicable for bulk filtrometry, but only using 5-microm filters.