In the course of the last two decades, it has become increasingly evident that the sarcolemmal, sarcoplasmic reticular and mitochondrial membrane systems play an important role in determining the status of heart funotion in health and disease. These organelles have been shown to be intimately involved in the regulation of cation movements during the contraotion-relaxation cycle. Various proteins imbedded in the phospholipid 2+ + - + + bilayers of these membranes control Ca ,Na, Cl ,K and H concentrations within the oytoplasm by indirect or direct means. Cationic channels, Na+, + 2+ 2+ 2+ + 2+ + + K -ATPase, Ca IMg ATPase, Ca pump, Na -Ca exchanger, Na -II exchanger and adenylate cyclase affect myocardial funotion and viability through their role as regulators of specific ion movements. However, proteins are not the only important constituents of the membrane. Any disturbance in the interaction between proteins and phospholipids in the membrane has been suggested to alter the funotion of the organelles, upset ionic homeostasis and precipitate the development of abnormalities in oardiac performance. It is, therefore, orucial to understand the faotors whioh regulate membrane funotion in their totality if we are to oomprehend the nature of heart performanoe in healthy subjects. Similarly, the study of membrane dysfunotion in a wide variety of experimental models of heart disease at various stages of failure is essential if we are to fully understand the pathogenesis of heart dysfunotion and improve its treatment.

Zusammenfassung
Proceedings of the Symposium held at the 8th Annual Meeting of the American Section of the International Society for Heart Research, July 8-11, 1986, Winnipeg, Canada

Inhalt
A. Special Lecture.- 1. Molecular Biology and Cardiac Function, Past, Present and Future.- B. Electrical Events and Ions.- 2. Regulation of Calcium Slow Channels and Potassium Channels of Cardiac Muscle by Cyclic Nucleotides and Metabolism.- 3. Potassium Channels Identified with Single Channel Recordings and Their Role in Cardiac Excitation.- 4. Na and Ca Channels in the Heart.- 5. Sodium Pathways In and Out of the Cardiac Cells: Relationship to Inotropy.- 6. Nondriven Electrical Activity in Cardiac Ventricular Fibers.- 7. Regulation of Cl? Activity in Ventricular Muscle: Cl?/HCO?3 Exchange and Na+ dependent Cl? Cotransport.- C. Sarcolemmal Functions.- 8. Parasympathetic Control of the Heart: Subcellular Mechanisms.- 9. Role of Phosphatidylethanolamine N-Methylation on Ca2+ Transport in Cardiac Membranes.- 10. Na+ - Ca2+ Exchange in Cardiac Sarcolemmal Vesicles.- 11. Na/K Pump Function in Cultured Embryonic Chick Heart Cells.- 12. Characteristics of Ca2+/Mg2+ ATPase in Heart Sarcolemma Treated with Trypsin.- D. Sarcoplasmic Reticulum Function.- 13. Depression of Canine Ventricular Sarcoplasmic Reticulum by the Calcium Channel Agonist, Bay K 8644.- 14. Biophysical Aspects of Ca2+ Transport Sites in Skeletal and Cardiac Sarcoplasmic Reticulum (Ca2+ + Mg2+)ATPase.- 15. Mechanisms of Sarcoplasmic Reticulum Functions and Consequences for Muscle Activity.- 16. Protein Phosphorylation in Cardiac Sarcoplasmic Reticulum and Its Functional Consequences.- 17. The Ca2+ ATPase of Cardiac Muscle Sarcoplasmic Reticulum.- E. Contractile Protein Functions.- 18. Contractile and Regulatory Proteins in Cardiovascular System.- 19. Distribution of Cardiac Myosin Isozymes in Human and Rat Heart-Immunohistochemical Study Using Monoclonal Antibodies.- 20. Remodelling of theMyocyte at a Molecular Level - Relationship Between Myosin Isoenzyme Population and Sarcoplasmic Reticulum.- 21. Isomyosins and Isoactins in Mammalian Myocardium.- 22. Crossbridge Mechanisms of Contraction in Vascular Smooth Muscle.- F. Functional Aspect of Metabolism.- 23. Control of Glucose Uptake and Utilization in the Myocardium.- 24. Blockade of Sugar Transport Decreases Contractility of Aortic Smooth Muscle.- 25. Control of Energy Transport in Cardiac Muscle. Dissociation of ATP Levels from Contractile Function; Cardiac Failure Due to Phosphocreatine Deficiency.- 26. Creatine Kinase and Mechanical Properties of Rat Ventricular Muscle.- 27. Hemodynamic Performance of Creatine-Depleted Rat Heart in Isolated Blood-Perfused Working Preparation.- 28. Localization of Glucose-6-Phosphatase (G-6-Pase) in the Rat Heart Muscle Cells.