http://repub.eur.nl/res/aut/27692/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/22430/ 1996-03-27T00:00:00Z Already in ancient times the Greek were aware of the heart in the human body and they gave it the name kardia, which is still in use in words as cardiac, myocardial, tachycardia and bradycardia. In those times the importance of the heart was appraised by Aristotle (384-322 B.C.), who thought that the heart was the seat of the soul and centre of man. In 1628, however, the basis of the modern concepts of the circulation was laid by Harvey (1578-1657) who described the function of two ventricles of the heart and the whole-body blood circulation, and who gave the first description of heart failure (Harvey, 1628). Nowadays, it is known that the function of the systemic circulation is to deliver blood to all organs of the body in order to provide them with sufficient supply of oxygen and metabolic substrates. The blood supply to the organs is accomplished primarily by the pump function of the heart. The rhythmic contractions of the heart underlying this pumping action are elicited by the electrical signals raised by the specialized cells of the atnum. Thus, the initiation of contraction is dictated by the cellular organization, subsequently leading to the complex process termed excitation-contraction coupling occurring within cardiomyocytes. It are the phasic inward and outward movements of Ca2 + across the sarcolemma (SL) and the sarcoplasmic reticulum (SR) and the phasic on and off interactions of Ca'+ with the troponin C component of the sarcomeres that determine the operation of the contraction-relaxation cycle. Various regulatory mechanisms control these Ca2 + movements and interactions, processes which occur all within the confines of the cell membranes of the cardiomyocytes.