Peter Danilo

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BACKGROUND Ca2+ leak from the sarcoplasmic reticulum (SR) may play an important role in triggering and/or maintaining atrial arrhythmias, including atrial fibrillation (AF). Protein kinase A (PKA) hyperphosphorylation of the cardiac ryanodine receptor (RyR2) resulting in dissociation of the channel-stabilizing subunit calstabin2 (FK506-binding protein or(More)
We tested the ability of human mesenchymal stem cells (hMSCs) to deliver a biological pacemaker to the heart. hMSCs transfected with a cardiac pacemaker gene, mHCN2, by electroporation expressed high levels of Cs+-sensitive current (31.1+/-3.8 pA/pF at -150 mV) activating in the diastolic potential range with reversal potential of -37.5+/-1.0 mV, confirming(More)
BACKGROUND Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. METHODS AND RESULTS We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during(More)
BACKGROUND Cardiac memory (CM) refers to T-wave changes induced by ventricular pacing or arrhythmia that accumulate in magnitude and duration with repeated episodes of abnormal activation. We report herein the kinetics of long-term CM and its association with the ventricular action potential. METHODS AND RESULTS Dogs were paced from the ventricles at(More)
Cardiac memory (CM) has short- (STCM) and long-term (LTCM) components modulated by calcium and angiotensin II. LTCM is associated with reduced Ito and Kv4.3 mRNA levels. Because the cAMP response element binding protein, CREB, contributes to CNS memory transcription, we hypothesized that it might be a transcriptional factor in CM, influenced by calcium and(More)
OBJECTIVE Our goal was to study rate adaptation of atrial action potentials in non-steady and steady states to further our understanding of mechanisms determining inducibility and stability of atrial fibrillation. METHODS We used standard microelectrode techniques to examine the characteristics of steady-state action potentials paced at regular cycle(More)
BACKGROUND Questions remain about the contributions of transmural versus apicobasal repolarization gradients to the configuration of the T wave in control settings and after the induction of short-term cardiac memory. METHODS AND RESULTS Short-term cardiac memory is seen as T-wave changes induced by altered ventricular activation that persists after(More)
BACKGROUND We tested the hypothesis that ICa,L is important to the development of cardiac memory. METHODS AND RESULTS The effects of L-type Ca2+ channel blockade and beta-blockade were tested on acutely anesthetized and on chronically instrumented, conscious dogs. Short-term memory (STM) was induced by 2 hours of ventricular pacing and long-term memory(More)
OBJECTIVE Although the incidence of atrial fibrillation (AF) increases with age, the cellular electrophysiological changes that render the atria of aged individuals more susceptible to AF remain poorly understood. We hypothesized that dispersion of atrial repolarization increases with aging, creating a substrate for initiation of AF. METHODS Four groups(More)
BACKGROUND Calcium-insensitive transient outward current (I(to)) is important to the development of cardiac memory (CM), which itself reflects the capacity of the heart to remodel electrophysiologically. We used cardiac pacing to test the hypothesis that CM evolution can be explained by developmental maturation of I(to). METHODS AND RESULTS Acutely(More)