The fish gill is the primary interface between the fish and the fish's environment. The gill plays a major role in respiration and in the regulation of ion and water balance. Control of blood flow through this organ is then of primary importance in the maintenance of internal body fluid homeostasis. Dr. Olson plans a series of studies on the action and metabolism of hormones and hormone-like factors in the blood that regulate blood flow through the gill vascular network. Dr. Olson has developed a gill perfusion procedure that allows measurement of blood flow, blood pressure, etc. in the presence and absence of various agents such as angiotensin, bradykinin, biogenic amines, and other compounds that are known to be regulators of blood flow in other tissues. He has adapted the procedure so that he will be able to measure the uptake and metabolism of these compounds by the gill tissue as they pass through the gill. He will then be able to correlate vascular changes with the metabolic events and determine which of these factors are the major actors in the regulation of blood flow. The research results are of primary importance to our understanding of the regulation of blood flow in respiratory organs. In addition the results will contribute to our understanding of hormone metabolism by gill tissue and to the role of environmental factors (i.e. pollutants) that might damage the gills and thereby disturb blood flow through the gills and upset hormone balance within the stressed fish.