Use of flow cytometry to extend and improve in vivo determinations of microvessel hematocrit and cell flux.
The use of fluorescent-erythrocyte tracer methods for estimating microvascular variables has been extended and improved by using flow cytometry. With cell tracer methods, the precision of estimates of cell flux, hematocrit, etc. is dependent on the labeled-cell fraction (p). In larger arterioles, high cell flux and the requirement to identify each labeled cell mandate the use of very low labeled-cell fractions. Precise microvascular estimates require high total cell counts in the estimation of p. This is not practical to do manually, but can be accomplished by flow cytometry. Determinations of p in experimental samples were made by both flow cytometry and microscopy. These values were compared to each other and to calculated values. In the range 0.0045 less than p less than 0.075, where manual counting statistics give CV(p) less than 0.12, counts by microscopy and flow cytometry were not significantly different. This confirms that flow cytometry identifies the same cell population as seen in vivo. Flow cytometry counts will resolve p greater than 0.00001 for rhodamine-labeled-cell fractions and p greater than 0.0002 for fluorescein-labeled-cell fractions. Rhodamine-labeled-cell fraction samples analyzed when fresh or after 1-3 weeks storage in RPMI 1640 media (GIBCO) gave p values which agreed to within 4%. We identify the use of rhodamine-labeled cells as a simple yet powerful method of rare-event analysis for many in vivo applications.
Sweeney
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Sarelius
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D000818:Animals; D001783:Blood Flow Velocity; D006224:Cricetinae; D004912:Erythrocytes / Q000166:cytology; D005434:Flow Cytometry / Q000379:methods; D005452:Fluoresceins; D006400:Hematocrit; D006801:Humans; D008833:Microcirculation / Q000502:physiology*; D012044:Regression Analysis; D012709:Serum Albumin
D005452:Fluoresceins; D012709:Serum Albumin