Seasonal variations in the biophysical properties of rabbit aorta and its susceptibility to arteriosclerosis.

The physiological variations in the mechanical properties of rabbit aortae in relation to the periods of hair shedding were studied. The load-strain curves of the eight proximal thoracic segment in 15 shedding and 15 non-shedding male albino rabbits were analysed. The slope of the curves (tangent of the angle between the linear region of the load-strain curve and the strain axis) was decreased in the shedding animals compared to that of the non-shedding animals and the toe of the load-strain curves was significantly lower towards the x-axis in the shedding animals. The observations indicate a lower stiffness, that is increased elasticity, of the aortae of rabbits during hair shedding. The increased elasticity during hair shedding may explain the previously reported resistance to experimental arteriosclerosis caused by the hemodynamic strain elicited by exposure to systemic hypoxia. A decrease in the aortic content of collagen and of sulfated glycosaminoglycans, and an increase in the content of hyaluronic acid, may be of importance in the alterations of the mechanical properties of rabbit aorta during hair shedding.