32 



HANDBOOK OF PHYSIOLOGY 



CIRCULATION I 



TABLE 2 



* BV = PV + CV. 



Data on rhesus monkeys from Gregersen et al. (97). The 

 first 4 columns are from their report, to which I have added 

 a calculation of the standard deviation for Hm/Hc termed 

 "^ceiis" in their report. CV/,' has been calculated as in table 

 I. The values given under the heading XPV are for e.xcess 

 plasma, and are discussed in the next section of this chapter. 



average of 0.917 with less variation (63). Since the 

 spleen in the dog contains an appreciable volume of 

 cells which are included in the calculation of //,„, but 

 which do not influence H^, its removal would be pre- 

 dicted to reduce the ratio H^/ H^. Reported values for 

 the ratio in unanesthetized splenectomized dogs 

 average 0.899 (^'9'^- 



Scattered data are available for other species. The 

 ratio H„/Hr in unanesthetized normal rats is given 

 in one report as 0.739, standard deviation 0.053 

 (236); while other investigators find the average ratio 

 to be 0.986, standard deviation 0.067 (■ ' 7)- If T- 1824 

 is used for PV in inice, the average ratio is 

 0.73, whereas if the smaller value for I"'-albumin PI' 

 is used it is 0.88 (242). Table 2 shows data obtained 

 by Gregersen and his colleagues (97) on the rhesus 

 monkey, to which I have added additional calcula- 

 tions as in table i , and a final column of values for 

 "excess plasma" which are discussed in a later section. 



Local Circulatory Hematocrits 



A variety of methods has been used to show that 

 the ratio cell label: plasma label in individual vascular 

 areas is different from the ratio in the central circula- 

 tion. They agree in showing that within a short time 

 after injection plasma label has expanded its virtual 

 distribution space in most tissues out of proportion 

 to the expansion of cell label space. Unfortunately, 

 none of the methods defines the extra plasma space 

 either anatomically or quantitatively, since none of 

 them distinguishes intravascular from extravascular 

 plasma label. It may be assumed with some confidence 

 that firmly bound cell label remains intravascular, 

 but this assumption cannot be made with equal con- 

 fidence for plasma label. 



Gibson and his colleagues (82) made the first study 

 of local differences by examining specimens of tissues 

 without grossly recognizable large vessels, 15 min or 

 so after cell and plasma labels had been injected. 

 Assuming that the ratio of the two labels represents 

 the ratio of cells to plasma in the small vessels of the 

 tissues, they obtained mean hematocrits for the con- 

 tents of these vessels by reference to the label ratio and 

 hematocrit of blood drawn from the central circula- 

 tion. Table 3 shows representative data from their 

 study. Similar data have been obtained by other in- 

 vestigators, using other cell and plasma labels (51, 58, 



65)- " 



Special attention has been given to the kidney, 

 which has been shown to be relatively cell-poor by 

 several independent methods. Pappenheimer & 

 Kinter (179) adjusted the arterial hematocrit by in- 

 jecting cells or plasma, and measured the change in 

 total renal hemoglobin in excised kidneys. When the 



.40 



2.05 

 1 .02 

 0.83 



0-37 

 0-55 

 0.42 



0-53 

 0-45 



From Gibson et al. (82). Average values for 7 normal 

 dogs under morphine narcosis. H, is the tissue hematocrit 

 with large vessels excluded (see text for method). H,/Hc is the 

 ratio of the tissue hematocrit to the hematocrit of the 

 central circulation (arterial blood drawn from a large ar- 

 tery). 



