Estimation of shear stress in contracting microlymphatic vessels
Conference Paper
Overview
Identity
Additional Document Info
View All
Overview
abstract
Collecting microlymphatics play an important role in promoting lymph flow from the initial lymphatics in the interstitial spaces to the large transport lymph ducts. In most tissues, the primary mechanism of producing this flow is the spontaneous contractions of the lymphatic wall. Lymphatic contractile activity is inhibited by flow in isolated lymphatics, however there are virtually no in situ measurements of lymph flow in these vessels. We determined lymph fluid velocities across multiple contraction cycles in several rats by tracking lymphocyte movement while simultaneous measuring vessel diameter. Lymph velocities ranged from -4.7 mm/sec to 7.5 mm/sec with the average velocity being 1.2 mm/sec. The average diameter of the contracting lymphatics was 110 um and the average contraction velocity was 50 um/sec. From these values we estimated the wall shear stress experienced throughout the contraction cycle. Given the low Wormersley parameter and low Reynolds number, we calculated the shear stress at an instant in time for the given vessel diameter and particle velocity using a Poiseuille flow model. Estimates of the wall shear averaged 1.0 dynes/cm2 with maximum shear stresses approaching 6.0. (Support: Whitaker Foundation Special Opportunity Grant, NIH HL-075199 and HL-070308).
