Journal of Applied Physiology, Vol 38, Issue 2 344-350, Copyright © 1975 by American Physiological Society
A microindentation technique to measure rheological properties of the vascular intima
B. S. Gow and R. N. Vaishnav
A microindentor was developed to measure the depth of indentation of the
intimal surface of arterial tissue loaded by flat-ended, cylindrical
probes. The depth of indentation depended on the initial stretch of the
tissue which required a rigid support (plaster of Paris) beneath the
adventitial surface. Probe tips used ranged from 550-mum down to 65-mum
diameter while loads ranged from 800 to 15 mg. The depth of indentation was
markedly time dependent; that obtained 30 s after loading (variation of 30)
was reproducible and served as a useful parameter of viscoelasticity of the
aortic intima and supporting tissues of dog and man. The mean variation of
30 (0.19-mm diam tip, 120-mg load), obtained from longitudinal series of
indentations of nine dog aortas, ranged from 40.8 to 68.8 mum while
coefficient of variation in these series ranged from 4.8 to 15.9%. Intimal
pads were found to have greater resistance to identation than adjacent
tissue; likewise the tissue on the dorsal, intimal surface of the aorta had
lower variation of 30 values compared with the rest of the intima.
Lipid-filled intimal regions were about twice as complaint as
macroscopically spared areas. The technique should prove useful in
understanding the microrheological response of the blood vascular interface
to hydrodynamic stresses.
