A simple method for vital staining of elastin in arterial tissue.

Highly diluted solutions of Gentian Violet and Evans Blue were used to visualize the elastin network in viable porcine right common carotid artery (RCCA) preparations. The two simple, alternative methods of staining were applied to proximal, intermediate, and distal sections of RCCA under various experimental conditions. These included the state of the vessel wall soon after excision, under relaxed smooth muscle condition after preconditioning, and during vasoconstriction. Micrographs of arterial rings, sectors, and axial strips show that the RCCA is an artery of the elastic type at the proximal end and of the muscular type at the distal end. While in sections of freshly dissected or KCl-constricted arteries the elastic lamellae show the well-known waviness, those in sections from arteries with relaxed smooth muscle and after preconditioning appear nearly straight. It is hoped that the inexpensive staining tools will contribute to solve conflicting interpretations existing on elastin structures in the arterial wall.

Passive mechanical properties of porcine left circumflex artery and its mathematical description.

The aim of this study was to analyze the pseudoelastic behavior of the coronary wall in vitro and to describe this behavior with three alternative strain energy functions frequently used in arterial mechanics. Six tubular segments of artery were subjected to various levels of simultaneous transmural pressure and axial force encompassing the physiological range of loading. Measured data on force, pressure, stress-free geometry and vessel deformation were used to compute components of the Green strain tensor and to determine by least squares fit the values of constants appearing in the following strain energy functions: Fung's exponential function, a combined polynomial-exponential form and a neo-Hookean plus exponential expression. The results obtained showed large biological variability. A comparison of the relative magnitude of the strain components did not reveal significant deviations from orthotropy under the given experimental conditions, hence shear terms were not included in the present constitutive formulations. The deformational behavior of the coronary artery displayed the high non-linearity typical for arteries of the muscular type. For states of equibiaxial stress the corresponding strains in the axial direction were larger than those in the circumferential direction, at least for loads in the upper and physiological range. All these aspects of coronary elasticity were mimicked fairly well by all three functions, although with slightly different degrees of accuracy.