This volume constitutes the proceedings of a satellite symposium of the XXXth congress of the International Union of Physiological Sciences. The symposium has been held In Banff, Alberta Canada July 9-11 1986. The program was organized to provide a selective overview of current developments in cardiac biophysics, biochemistry, and physiology. In order to highlight areas of develop ing ideas and to stimulate the participants' inquisitiveness into the nature and complexity of the integrated cardiovascular system, lectures and discussions were presented that emphasized evolving and sometimes provocative concepts in the field. With the same goal in mind we have, for the readers of this volume, briefly summarized the general discussions. We would like to thank several individuals whose dedication made this sym posium and publication of the proceedings possible. Mrs. Lois Kokoski and Mrs. Madeleine Aldridge of the Conference Office of the University of Calgary seemingly effortlessly handled the details of the symposium. Peter de Tombe, Dr. Peter Backx and Dr. Jeroen Bucx transcribed the general discussions. Finally, we appreciate the extra effort of our secretaries, Lenore Doell and Gregory Douglas, and the work of Anna Tyberg who prepared the final manuscripts for publication. Henk E.D.J. ter Keurs, M.D. Ph.D. John V. Tyberg, M.D. Ph.D.

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Preface.- 1. How do crossbridges produce the sliding force between actin and myosin filaments in muscle.- 2. Stepwise shortening and the mechanism of msucle contraction.- 3. Mechanics of the myofibril.- Discussion.- 4. Excitation-contraction coupling in myocardium: Implications of calcium release and Na/Ca exchange.- 5. Calcium influx and sarcoplasmic reticulum calcium release in cardiac excitation contraction coupling.- Discussion.- 6. Cardiac energetics.- 7. Energetics of the heart.- Discussion.- 8. On the force-length relation in myocardium.- 9. Segment length mechanics of cardiac muscle.- Discussion.- 10. Regulation of the actin-myosin interaction by calcium; the troponin tropomyosin complex.- 11. Evidence that a decrease in sarcomere length reduces the affinity of troponin in the intact cardiac myofibril.- Discussion.- 12. Mechanics of cardiac contraction and the phosphorylation of sarcotubular and myofilament proteins.- Discussion.- 13. Ventricular pump function and arterial resistance.- 14. Ventricular wall motion.- Discussion.- 15. Mechanics of the ventricular septum.- 16. Mechanics of the interventricular septum.- Discussion.- 17. On the interaction between the pericardium and the heart.- 18. The mechanical effects of the pericardium on the left ventricle.- Discussion.- 19. Role of a changing venous capacitance in cardiovascular homeostasis.- 20. Role of a changing venous capacitance in cardiovascular homeostasis.- Discussion.- 21. Principles of arterial hemodynamics.- 22. Arterial dynamics: a comment on arterial wave reflections.- Discussion.- 23. Control of the circulation.