According to our hypothesis, the age-related gradual decrease of stimuli originating from sympathetic nervous endings lead to a variety of metabolic derangements in the vessel wall. Our recently obtained results indicate that when the vessel wall is deprived of adrenergic stimulation, changes will occur which resemble those seen in the natural process of aging. Therefore, we propose a multidisciplinary study analyzing mechanical properties, collagen content and synthesis, selected enzymes participating in the Krebs cycle and the morphology of arteries obtained under the following conditions: 1) Surgically sympathectomized rabbits; 2) Chemically sympathectomized rabbits (12 and 16 weeks respectively). The effects will be compared with properly matched control groups. 3) In order to analyze the type of sympathetic nervous stimuli responsible for the post-sympathectomy arterial wall effects, sympatholytic substances will be tested as to their effect on the arterial wall. Special attention will be given to determine which component of the sympathetic activity is more closely related to the metabolism of the arterial wall and the possible relationship to the degenerative process in the arterial wall. Generally, biochemical changes in the arteries will be correlated with their mechanical properties. 4) The effect of sympathectomy will be tested on two different strains of pigeons, atherosclerosis susceptible (White Carneau) and atherosclerosis resistant (Show Racer). 5) The power law will be applied to express the strain energy function as a parameter characterizing the mechanical properties. It can be expected that a successful completion of this stage will have a significant influence on the further understanding of the etiology and the pathogenesis of degenerative arterial disease which is the prerequisite for future rational therapeutic and perhaps even preventive concepts.