AJP - Heart and Circulatory Physiology, Vol 244, Issue 5 635-H643, Copyright © 1983 by American Physiological Society
Ratio of cells and plasma in blood flowing past branches in small plastic channels
J. W. Dellimore, M. J. Dunlop and P. B. Canham
Red cell concentrations related to flow were studied by measuring delivered
cell fractions from branching channels. A branched channel in a plastic
block was cast by pouring setting plastic into a mold containing two 0.18
mm steel wires; one was beveled and touching, at 60 degrees, the side of
the other wire, which extended across the mold. The wires were later
withdrawn. Two of these flow chambers were perfused (flow of 0.14 ml/min)
with human blood or blood diluted with host plasma (anticoagulant
ethylenediaminetetra-acetic acid), and the percent cell volume was measured
in the collecting tubes. The difference in hematocrit from the two outflow
channels was a linear function of the proportional flow in the side branch,
and the average slope for 29 experiments was 32.0 +/- 9.7 (SD)% with a
negative dependence on inflow hematocrit (correlation coefficient -0.63, P
less than 1%). When analyzed as cell flux ratio vs. flow ratio the data
show a significant deviation from the line of identity, which is most
marked for the lowest values of hematocrit that we studied (approximately
equal to 20%). We concluded that if the model branching channels are
representative of arteriolar-sized blood vessels, then there is the
potential for wide variations in hematocrit in the microcirculation,
especially in blood with a low cellular fraction.
