The overall objectives of this research project are to evaluate the hemodynamic and metabolic effects of neuro-humorally induced vasoconstriction on metabolically augmented skeletal muscle blood flow. These studies are designed to gain a better understanding of how the patient with heart failure copes with the stress of exercise. When the patient with heart failure exercises, there is an exaggerated sympathoadrenal response. The goals of the proposed project are to determine how this response would be expected to alter skeletal muscle blood flow and metabolism during exercise. The model which was utilized in the present research is an isolated canine gracilis muscle preparation which can be stimulated to contract and in which skeletal muscle tension can be highly controlled. In this model blood flow to skeletal muscle can be measured and the arterial/venous differences in oxygen and substrates measured and evaluated. BIBLIOGRAPHIC REFERENCES: Zelis, Robert, Nellis, Stephen H., Longhurst, John, Lee, Garrett, and Mason, Dean T.: Abnormalities in the Regional Circulations Accompanying Congestive Heart Failure. Progress in Cardiovascular Diseases l8: l8l-l99, l975. Nellis, S.H., Pope, J.R., Zelis, R., Beech, A., and Crede, W.: Adverse effects of high-dose norepinephrine on oxygen consumption during gracilis muscle static exercise. Clinical Research 23 (3) : 199A, l975.