This paper deals with the mathematical model that describes function of human heart. More specifically, it addresses equations express electromechanical process, is mechanical deformation (contraction and relaxation) heart muscle induced by electrical field that, at every heartbeat, generated in sino-atrial node then propagates all across cardiac cells. After deriving from basic physical princi...

On the coronary circulation, the effect of catecholamines was disputed by many investigators, and there is general agreement that catecholamines increase the coronary blood flow. However, some researchers attributed this vasodilatation to myocardial stimulation and consequent metabolic vasodilatation rather than to direct action to the coronary artery1,2,3). On the other hand, ZUBERBUHLER and B...

Hyperpolarization-activated current (If) is the major ionic current contributing to the spontaneous diastolic depolarization of cardiac sinus node pacemaker cells. It is mediated by hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels. However, several observations support a potential role of HCN channels in the arrhythmogenesis of working myocardium under pathological conditi...

Mammalian sinoatrial node (SAN) cells, the natural pacemaker cells of the heart, have an action potential characterized by the presence of a special phase, the slow diastolic (pacemaker) depolarization (phase 4), which drives pacemaker activity and has therefore attracted the interest of generations of cardiac physiologists. What is the basis of the pacemaker depolarization? Here the features o...

The effect of extreme calcium reduction was studied in rabbit sino-atrial node cells treated with K-free media. Ca removal (Ca = 0, EGTA = 6 mM) suppressed spontaneous miniature fluctuations elicited by exposure to the K-free media. Further, successive exposure to the Ca-free, EGTA solutions produced a propagated action potential and suppressed a contracture. The action potential was not notice...

Atrial fibrillation is the most common cardiac arrhythmia. Structural cardiac defects such as fibrosis and gap junction remodeling lead to a reduced cellular electrical coupling and are known to promote atrial fibrillation. It has been observed that the expression of the hyperpolarization-activated current If is increased under pathological conditions. Recent experimental data indicate a possib...

Cardiac and coronary vasodilator effects of gentamicin (GM) were investigated in isolated, blood-perfused papillary muscle, sino-atrial (SA) node and atrioventricular (AV) node preparations of dogs. GM (0.3-100 mumol) was injected intraarterially. GM produced an increase in coronary blood flow in all preparations. In paced papillary muscle preparations, GM reduced the force of contraction. In s...