OF THESIS CORRELATING THE MAGNITUDE AND SPATIAL GRADIENT OF ALTERNANS Electrical restitution has been shown to inaccurately predict the occurrence of alternans of action potential duration. A new method using the spatial gradient of alternans (SGA) is proposed to predict alternans and cardiac electrical stability. A simulated 1-D strand of tissue was used to compare indexes computed from restit...

BACKGROUND Restitution kinetics and alternans of ventricular action potential duration (APD) have been shown to be important determinants of cardiac electrical stability. In this study, we tested the hypothesis that APD restitution and alternans properties differ between normal and diseased human ventricular myocardium. METHODS AND RESULTS Monophasic action potentials were recorded from the r...

Early epithelial restitution occurs as a consequence of intestinal epithelial cell (IEC) migration after wounding, and its defective regulation is implicated in various critical pathological conditions. Polyamines stimulate intestinal epithelial restitution, but their exact mechanism remains unclear. Canonical transient receptor potential-1 (TRPC1)-mediated Ca(2+) signaling is crucial for stimu...

This study was conducted to determine whether the contributions of epidermal growth factor (EGF) to gastric mucosal restitution after injury are mediated by stimulation of Na(+)/H(+) exchangers in surface mucous cells (SMC). Intact sheets of guinea pig gastric mucosae were incubated in vitro. Intracellular pH (pH(i)) in SMC was measured fluorometrically, using 2',7'- bis-(2-carboxyethyl)-5-(and...

abstract Discordant alternans, the phenomenon of separate cardiac tissue locations exhibiting action potential duration (APD) alternans of opposite phase, appears to be a potential mechanism for electrocardiographic T wave alternans, but its initiation mechanism is unknown. We studied behavior of one-and two-dimensional cardiac tissue spatially homogeneous in all respects, including APD restitu...

Gap junctions and sodium channels are the major molecular determinants of normal and abnormal electrical conduction through the myocardium, however, their exact contributions to arrhythmogenesis are unclear. We examined conduction and recovery properties of regular (S1) and extrasystolic (S2) action potentials (APs), S1S2 restitution and ventricular arrhythmogenicity using the gap junction and ...

OBJECTIVE The restitution mechanism has been the focus of attention as the possible mechanism behind ventricular fibrillation (VF). However, its contribution in chronic ischemic heart has not been established. METHODS We investigated chronic ischemic dogs with occlusion of left anterior descending artery. Sixty unipolar electrograms were simultaneously recorded from an entire cardiac surface....

Chemokines and other immune mediators enhance epithelial barrier repair. The intestinal barrier is established by highly regulated cell-cell contacts between epithelial cells. The goal of these studies was to define the role for the chemokine CXCL12 in regulating E-cadherin during collective sheet migration during epithelial restitution. Mechanisms regulating E-cadherin were investigated using ...

The mechanical restitution of the left ventricle of closed-chest dogs was modeled as a monoexponential relation, using peak single-beat elastance as a measure of contractile strength. Data were obtained from nine dogs chronically instrumented with three sets of piezoelectric diameter gauges to assess ventricular volume and high-fidelity manometers to measure pressure. Mechanical restitution cur...