These Proceedings are from the Fifth Annual Meeting of the American Section of the International Society for Heart Research held at Hilton Head Island, South Carolina, September 21-24, 1983. The program and abstracts were published in the Journal of Molecular and Cellular Cardiology, Vol. 15, Supplement 4, September 1983, Academic Press. This Symposium Proceedings consists of three sections. Section I deals with the mechanical factors and their i'nfluence on coronary blood flow in the normal and failing heart. Section II is developed around the area of vascular smooth muscle and the factors that may control it which ultimately play such an important role in the regulation of coronary blood flow. Section III is primarily devoted to the mechanical aspects of the function of the heart in both hypertrophy and failure including the molecular changes in the myocyte, alterations in neural control, and in inotropic responsiveness of the hypertrophied and failing heart. The editors hope that these three areas encompass a significant body of new and ongoing information that will be helpful to those who work in these areas as well as those who treat patients with varying degrees of myocardial failure or with compromised coronary circulations. The editors express their appreciation to all the contributors and to Ms. Jeri B. McClain for assisting in the organization and compiling of this volume. Francis L. Abel, M. D., Ph. D. Walter H. Newman, Ph. D.