The response of the peripheral vasculature to chronic venous distention will be evaluated by determining changes in resistance in the large artery, small vessel, and venous segments of the vascular tree resulting from chronic venous occlusion. The role of altered vascular lumen anatomy in the changes in vascular function will be determined by observing the change in resistances following removal of vascular tone by perfusion of a metabolic blocker. The role of anatomical changes of the venous wall in the altered vascular function will be evaluated by measurements of resting venous size and venous distensibility. Alterations in the size, numbers and patterns of veins and competence of values will be evaluated from casts of vasculature. All results will be compared to a paired normal extremity. Acute increases in venous pressure will be related to functional changes in resistances of the segments of the vascular tree and to edema formation and nutritional exchange. The role of the symphatic nerves in the altered vascular function will be determined by observation of changes resulting from gamma-blockade. The effectiveness of various therapeutic procedures in stimulating collateral development will be evaluated in rats from claudication time, pressure differential across the collateral bed and anatomic collateral resistance as determined from vascular casts.