Correlation of Visco-elastic Properties of Large Arteries with Microscopic Structure

Abstract

The media of 14 regions of the aorta and 3 regions of the pulmonary artery of dogs were subjected to a step-function circumferential stretch taking 20 msec to complete. The tension rose synchronously with the increase in circumference, then dropped exponentially to a reasonably steady state within 2 sec. A mathematical model, developed consistent with this stress-relaxation curve, showed how to use the tension curves to measure a viscous, a serieselastic, and a parallel-elastic constant unique for a given curve. These constants were compared with the microscopic structure of the same or similar segments; collagen was determined as hydroxyproline in a water soluble fraction, elastin as hydroxyproline in the residue and from the width and number of elastic lamellae, and muscle from the nitrogen content of a nonfibrous fraction, from cell counts and from contractility. The constituents varied widely and independently enough to permit correlating viscous and elastic constants with microscopic structure. The viscous and series-elastic constants were higher where muscle content was high, and increased markedly when the muscle was tonically contracted. The parallel-elastic constant was high when elastin was high and in the presence of contracted muscle, but seemed independent of collagen content, at the moderate tensions tested.

Viscoelastic properties of the rectal wall in Hirschsprung's disease.

“…This method was applied here by studying the adaptation of the rectal wall to a sudden distension in Hirschsprung's disease. In in vitro studies, the smooth muscle has a greater viscosity when contracted than when relaxed (16). This is in agreement with our findings in this study.…”

Pressure/cross-sectional area relations in the proximal urethra of healthy males Part III: The time dependent pressure response following forced dilation: standardization of a technique

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A Dynamic Model of the Cervical Spine and Head

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