One of the currently most expanding and exciting areas in cardiovascular research is the study of receipt and dispatch of chemical signals by different cell types. Major progress has been made during the last years and a number of intercellular mediators have been structurally identified and their regulation studied. The impressive developments in molecular biology have provided most effective tools, enabling us to understand message generation in much more detail than anyone would have appreciated a couple of years ago. These developments also have a major impact on cardiovascular pharmacology. This involves both the molecular design of new drugs as well as an improved understanding of how established drugs act. Clearly, changes in one mediator system will also affect others and it might be difficult to take out just one factor and to ignore others. This is definitely true for myocardial ischemia where many different mediators are synthesized and released at about the same time, resulting in a complex picture of events and an even more difficult selection of the most appropriate drug therapy.