Prostaglandins and leukotrienes are two groups of compounds which are important biological regulators. They are synthesized from 20 carbon fatty acids found in cell membranes of many organisms. A great deal is known about the structure and function of these compounds in mammals, but the information is limited in non-mammalian vertebrates. In mammals, prostaglandins are involved in inflammatory responses, cardivascular regulation, blood clotting, and reproductive physiology, among other functions. Leukotrienes are involved in allergic reactions. Thus, regulation of the synthesis and actions of these compounds is important to human medicine. It is important to examine poikilothermic animals such as amphibians and fish, since they respond to changes in environmental temperature with dramatic alterations in their physiological and biochemical parameters. The ratios of the 20 carbon fatty acid precursors change in animals exposed to different environmental temperatures, and chemical reactions involved in synthesis may be faster or slower depending on the temperature or the other membrane fatty acids which are present. This research will examine the synthesis of prostaglandins and leukotrienes and investigate their biological roles in amphibians and fish. Dr. Herman has discovered that leukotrienes have different effects on the heart and on blood pressure of amphibians than they do on blood pressure in mammals. The reasons for the differences will be studied. The possibility that these animals produce novel compounds with different biological effects will be investigated. This information will provide a better understanding of the synthesis and biological roles of these important regulator compounds