Application of the "two-slit" photometric technique to the measurement of microvascular volumetric flow rates

Herbert H. Lipowsky, Benjamin W. Zweifach

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In vitro studies of red cell suspensions flowing through glass tubes were performed to provide additional details on the empirical relationship between red cell velocity measured by the "twoslit" photometric technique along the vessel centerline, V{A figure is presented}, and the mean velocity of cells plus plasma, Vmean. Small bore glass tubes (17- to 60-μm internal diameter) were used to simulate a blanket application of this method to the microcirculation. The previously established ratio, V{A figure is presented} Vmean = 1.6, was found to be valid within 5 to 10% in these tubes and for velocities within the physiological range. For tube diameters decreasing from 60 to 17 μm, V{A figure is presented} Vmean was found to increase slightly but was still within 10% of the 1.6 ratio. Analysis of earlier in vivo studies of the single-file motion of red cells in 6- to 10-μm capillaries, suggests that below 10 μm, V{A figure is presented} Vmean should approach a value on the order of 1.3, or 19% below the 1.6 factor.

Original languageEnglish (US)
Pages (from-to)93-101
Number of pages9
JournalMicrovascular Research
Issue number1
StatePublished - Jan 1978


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cardiology and Cardiovascular Medicine
  • Cell Biology

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