Spiral wave breakup is a proposed mechanism underlying the transition from ventricular tachycardia to fibrillation. We examined the importance of the restitution of action potential duration (APD) and of conduction velocity (CV) to the stability of spiral wave reentry in a two-dimensional sheet of simulated cardiac tissue. The Luo-Rudy ventricular action potential model was modified to eliminat...

INTRODUCTION Electrical restitution, relating action potential duration (APD) to diastolic interval (DI), was believed to determine the stability of heart rhythm. However, recent studies demonstrate that stability also depends on long-term APD changes caused by memory. This study presents a new method for investigation of rate- and memory-dependent aspects of restitution and for assessment of m...

This study was conducted to determine the contribution of ion transport to restitution after injury in the gastric mucosa. For this, intact sheets of stomach from the bullfrog, Rana catesbeiana, were mounted in Ussing chambers. Restitution was evaluated in the presence or absence of ion transport inhibitors amiloride, DIDS, and bumetanide to block Na(+)/H(+) exchange, Cl(-)/HCO(3)(-) exchange a...

Results Compared with paroxysmal AF, patients with persistent AF had shorter left atrial APD and effective refractory period (p 0.01). In paroxysmal AF, maximum left atrial APD restitution slope was 1.5 0.4; and 12 of 13 patients had slope 1 (p 0.001). In persistent AF, PACs encountered prolonged activation for a wider range of beats than in paroxysmal AF (p 0.01), which prolonged DI and flatte...

Restitution of action potential duration (APD) is thought to be critical in activation instability. Although restitution is used to predict APD during sequential changes in diastolic interval (DI), currently used protocols to determine restitution do not use sequential changes in DI. We explored restitution using a new pacing protocol to change DI sequentially and independently of APD. Transmem...

Rapid epithelial repair (restitution) after injury is required to maintain barrier function of the gastrointestinal mucosa and skin and is thought to be a highly ATP-dependent process that would be inhibited under hypoxic conditions. However, little is known about the metabolic pathways required for restitution. Thus, this study was undertaken to evaluate, in vitro, the role of oxidative respir...

Hoit, Brian D., Vivek J. Kadambi, Daniel A. Tramuta, Nancy Ball, Evangelia G. Kranias, and Richard A. Walsh. Influence of sarcoplasmic reticulum calcium loading on mechanical and relaxation restitution. Am. J. Physiol. Heart Circ. Physiol. 278: H958–H963, 2000.—Mechanical and relaxation restitution represent the restoration of contractile force and relaxation, respectively, in premature beats h...

In the present work, the effect of the restitution coefficient on the numerical results for a binary mixture system of sand particles and char particles in a bubbling fluidized bed with a huge difference between the particles in terms of density and volume fraction has been studied based on two-fluid model along with the kinetic theory of granular flow. Results show that the effect of restituti...

Sudden cardiac death remains a major public health problem in the United States. Ventricular fibrillation (VF) is the most common arrhythmia that directly leads to sudden cardiac death. However, the mechanisms of VF are unclear. Recently,1 2 different types of VF have been demonstrated in isolated, perfused rabbit hearts linked to the electrical restitution properties of the heart (ie, the dyna...

We investigated the function of the monocarboxylate transporter MCT1 in restitution of gastric surface mucous cells. Restitution is the repair mechanism by which cells migrate to cover an injured area. Cell migration after injury is dependent upon glycolysis, which under some conditions yields the waste product lactate. We used the bioflavenoid phloretin, a known inhibitor of MCT1, to block lac...