Circulating and tissue hematocrits of normal unanesthetized mice

Abstract

The circulating and tissue hematocrits of normal unanesthetized mice were determined by means of independent red cell and plasma volume measurements. The red cell volume-indicator which was used in this study was radioiron (Fe⁵⁹) tagged red cells. The plasma volume data were derived by means of radioiodine (I¹³¹) labeled serum albumin and were reported earlier (Friedman, Proc. Soc. Exper. Biol. & Med. 88: 323, 1955). The hematocrits of the various tissues were found to be: for spleen 51.3, lung 47.9, muscle 49.9, liver 38.9, intestine, 32.2, skin 29.2 and kidney 24.0%. The total body hematocrit was 35.4% as compared to 48.4 for venous blood. All tissues, with the exception of spleen and lung, contained hematocrits which were lower than that of venous blood suggesting the presence of some mechanism within the various tissues which is capable of effectively separating plasma from red cells.