The overall objectives of the proposed research are to fully explain the temporal contribution of chemical and myogenic factors in local regulation of blood flow through heart, skeletal muscle or kidney in health and in certain diseases. The research goals set for the current year are: 1) We plan to extend our studies dealing with ATP metabolism in various systemic organs. We have previously shown that high levels of exogenous ATP is converted to AMP on a single pass through most systemic organs (skeletal muscle, intestine, heart). We are now repeating these studies to make sure that low levels (levels more likely to normally occur) of ATP are metabolized in the same way. 2) To examine in detail the possibility that PGI2 and/or thromboxanes play an important role in coronary blood flow regulation. 3) Investigate the actions of local changes in O2, CO2 and sympathetic nerve stimulation alone and in combination on the right coronary circulation of the pig. 4) To begin to characterize local vascular control mechanisms in the tongue circulation of the dog. 5) To begin studies that examine the actions of certain clinically used anesthetics on the heart and coronary circulation of the dog and pig under normal and abnormal situations.