HYDRATION OF CONNECTIVE TISSUE AND TENDON ELASTICITY.

Abstract

Abstract 1. The objective of this study was to determine the influence of hydration on elasticity of aging connective tissue. Involvement of tendon elasticity in age-produced joint stiffness was discussed in terms of the biophysical properties of hydrated rat-tail tendons. 2. Kinetic analysis of tendons swelling in water revealed that a dispersive factor (A) and a cohesive factor (B) relate the velocity of swelling (dW/dt) to tendon weight (W) by the equation: dW/dt = ks(A/W − BW). Aging and longitudinal stress reduced the maximum swelling ratio (W∞/W0) and hastened equilibration. Elongation of tendons occurred with hydration, and kinetic analysis showed that lengthening strongly depends upon solution temperature, dielectric constant, and ionic strength. It was accepted, consequently, that electrostatic factors along collagen and mucopolysaccharide macromolecules greatly influence the hydration and elasticity of tendons. Displacement of water by alcohols elevated the elastic modulus. However, the force required to produce a 1 % extension, a stress-strain relationship, did not change with aging. Thermoelastic measurements indicated that the glass and shrinkage transition temperatures also did not change with animal age. 3. From these observations of biophysical properties, it was concluded that flexebility of tendon is very sensitive to solution parameters. A glass-state of macromolecular structure also contributes to molecular cohesiveness of collagen and mucopolysaccharide. Production of joint-stiffness, therefore, could be influenced by these physical-chemical factors. However, deleterious effects produced in the articular cartilage, causing an elevation in surface friction, also was considered as a possible factor.