Medicine and Health Sciences Commons^™

Microcurrent-Mediated Modulation Of Myofibroblasts For Cardiac Repair And Regeneration, Dipthi Bachamanda Somesh, Karsten Jürchott, Thomas Giesel, Thomas Töllner, Alexander Prehn, Jan-Peter Richters, Dragana Kosevic, J. Eduardo Rame, Peter Göttel, Johannes Müller

Division of Cardiology Faculty Papers

Cardiovascular diseases are a significant cause of illness and death worldwide, often resulting in myofibroblast differentiation, pathological remodeling, and fibrosis, characterized by excessive extracellular matrix protein deposition. Treatment options for cardiac fibrosis that can effectively target myofibroblast activation and ECM deposition are limited, necessitating an unmet need for new therapeutic approaches. In recent years, microcurrent therapy has demonstrated promising therapeutic effects, showcasing its translational potential in cardiac care. This study therefore sought to investigate the effects of microcurrent therapy on cardiac myofibroblasts, aiming to unravel its potential as a treatment for cardiac fibrosis and heart failure. The experimental design involved …

Effect Of Flecainide And Ibutilide Alone And In Combination To Terminate And Prevent Recurrence Of Atrial Fibrillation, Alexander Burashnikov, José M. Di Diego, Bence Patocskai, Debra S. Echt, Luiz Belardinelli, Charles Antzelevitch

Division of Cardiology Faculty Papers

BACKGROUND: There is a need for improved approaches to rhythm control therapy of atrial fibrillation (AF).

METHODS: The effectiveness of flecainide (1.5 µmol/L) and ibutilide (20 nmol/L), alone and in combination, to cardiovert and prevent AF recurrence was studied in canine-isolated coronary-perfused right atrioventricular preparations. We also examined the safety of the combination of flecainide (1.5 µmol/L) and ibutilide (50 nmol/L) using canine left ventricular wedge preparations.

RESULTS: Sustained AF (>1 hour) was inducible in 100%, 60%, 20%, and 0% of atria in the presence of acetylcholine alone, acetylcholine+ibutilide, acetylcholine+flecainide, and acetylcholine+ibutilide+flecainide, respectively. When used alone, flecainide and ibutilide …

Tachycardia Mediated Cardiomyopathy: Pathophysiology, Mechanisms, Clinical Features And Management., Shuchita Gupta, Vincent M. Figueredo, M.D.

Division of Cardiology Faculty Papers

Tachycardia mediated cardiomyopathy (TMC) is a reversible form of dilated cardiomyopathy that can occur with most supraventricular and ventricular arrhythmias. Despite the plethora of literature describing this entity in animal models, as well as humans, it remains poorly understood. Over the last decade, new etiologies of TMC, such as frequent premature ventricular complexes in normal hearts, have been identified. Recent advances in catheter-based ablation therapies, particularly for atrial fibrillation and ventricular arrhythmias, have added a new dimension to the treatment of this condition. This review describes the pathophysiology, proposed mechanisms, clinical features and management in various arrhythmic conditions.

Induction Of Autophagy Restores The Loss Of Sevoflurane Cardiac Preconditioning Seen With Prolonged Ischemic Insult., Mayumi Shiomi, Masami Miyamae, Genzou Takemura, Kazuhiro Kaneda, Yoshitaka Inamura, Anna Onishi, Shizuka Koshinuma, Yoshihiro Momota, Toshiaki Minami, Vincent M. Figueredo, M.D.

Division of Cardiology Faculty Papers

Sevoflurane preconditioning against myocardial ischemia-reperfusion injury is lost if the ischemic insult is too long. Emerging evidence suggests that induction of autophagy may also confer cardioprotection against ischemia-reperfusion injury. We examined whether induction of autophagy prolongs sevoflurane preconditioning protection during a longer ischemic insult. Isolated guinea pigs hearts were subjected to 30 or 45 min ischemia, followed by 120 min reperfusion (control). Anesthetic preconditioning was elicited with 2% sevoflurane for 10 min prior to ischemia (SEVO-30, SEVO-45). Chloramphenicol (autophagy upregulator, 300 µM) was administered starting 20 min before ischemia and throughout reperfusion in SEVO-45 (SEVO-45+CAP). To inhibit autophagy, 3-methyladenine (10 …

Hyperphosphorylation Of The Cardiac Ryanodine Receptor At Serine 2808 Is Not Involved In Cardiac Dysfunction After Myocardial Infarction., Hongyu Zhang, Catherine A Makarewich, Hajime Kubo, Wei Wang, Jason M Duran, Ying Li, Remus M Berretta, Walter J Koch, Xiongwen Chen, Erhe Gao, Héctor H Valdivia, Steven R Houser

Division of Cardiology Faculty Papers

RATIONALE: Abnormal behavior of the cardiac ryanodine receptor (RyR2) has been linked to cardiac arrhythmias and heart failure (HF) after myocardial infarction (MI). It has been proposed that protein kinase A (PKA) hyperphosphorylation of the RyR2 at a single residue, Ser-2808, is a critical mediator of RyR dysfunction, depressed cardiac performance, and HF after MI.

OBJECTIVE: We used a mouse model (RyRS2808A) in which PKA hyperphosphorylation of the RyR2 at Ser-2808 is prevented to determine whether loss of PKA phosphorylation at this site averts post MI cardiac pump dysfunction.

METHODS AND RESULTS: MI was induced in wild-type (WT) and S2808A …

Direct Evidence For Inhibition Of Mitochondrial Permeability Transition Pore Opening By Sevoflurane Preconditioning In Cardiomyocytes: Comparison With Cyclosporine A., Anna Onishi, Masami Miyamae, Kazuhiro Kaneda, Junichiro Kotani, Vincent M. Figueredo

Division of Cardiology Faculty Papers

To assess whether sevoflurane preconditioning is associated with inhibition of mitochondrial permeability transition pore (MPTP), the effects of sevoflurane were compared with those of cyclosporine A, a known inhibitor of MPTP opening. Isolated perfused guinea pig hearts underwent 30 min global ischemia and 120 min reperfusion (control). Sevoflurane preconditioning was elicited by administration of 2% sevoflurane for 10 min with 10 min washout before ischemia (sevoflurane). A preconditioning-like cardioprotection was also induced by administering cyclosporine A (0.2 μM) for 15 min, starting 5 min before ischemia and for 10 min after the onset of reperfusion (cyclosporine A). Left ventricular developed …

Cardioprotection By Regular Ethanol Consumption: Potential Mechanisms And Clinical Application., Masami Miyamae, Kazuhiro Kaneda, Naochika Domae, Vincent M. Figueredo, M.D.

Division of Cardiology Faculty Papers

Epidemiological studies demonstrate that excessive drinking is associated with hypertension, cerebral bleeding and loss of cardiac contractility. Conversely, studies have shown that mortality rates for people who regularly drink ethanol in moderation are lower than in abstainers, primarily due to decreased fatal ischemic heart disease. Further, moderate ethanol consumers have lower rates of myocardial infarction compared with abstainers. These beneficial cardiac effects may be due to pleiotropic effects of ethanol on lipids, platelets, and fibrinolytic activity. During the past decade, studies conducted in several animal models have revealed that light to moderate regular ethanol consumption renders hearts more tolerant to …

Acute Memory Phase Of Sevoflurane Preconditioning Is Associated With Sustained Translocation Of Protein Kinase C-Alpha And Epsilon, But Not Delta, In Isolated Guinea Pig Hearts., Chika Okusa, Masami Miyamae, Shingo Sugioka, Kazuhiro Kaneda, Yoshitaka Inamura, Anna Onishi, Naochika Domae, Junichiro Kotani, Vincent M. Figueredo

Division of Cardiology Faculty Papers

BACKGROUND AND OBJECTIVE: Anaesthetic preconditioning (APC) exerts cardioprotective effects by reducing infarct size and improving recovery of contractile function after ischaemia-reperfusion. The interval between brief exposure to volatile anaesthetic and sustained ischaemia, the acute memory phase, is dependent on intracellular signalling mediating this cardioprotection. Intramyocyte translocation of protein kinase C (PKC) is known to be a key mediator in APC. We examined the relationship between the time frame of the acute memory phase of sevoflurane preconditioning and intramyocyte translocation of PKC-alpha, delta and epsilon to the particulate fraction. METHODS: Isolated perfused guinea pig hearts were subjected to 30 min ischaemia …

Sevoflurane Enhances Ethanol-Induced Cardiac Preconditioning Through Modulation Of Protein Kinase C, Mitochondrial Katp Channels, And Nitric Oxide Synthase, In Guinea Pig Hearts., Kazuhiro Kaneda, Masami Miyamae, Shingo Sugioka, Chika Okusa, Yoshitaka Inamura, Naochika Domae, Junichiro Kotani, Vincent M. Figueredo

Division of Cardiology Faculty Papers

BACKGROUND: Volatile anesthetics and regular ethanol consumption induce cardioprotection mimicking ischemic preconditioning. We investigated whether sevoflurane enhances ethanol preconditioning and whether inhibition of protein kinase C (PKC) and mitochondrial K(ATP) channels attenuated this enhanced cardioprotection. The effects of regular ethanol consumption on expression of inducible (iNOS) and endothelial (eNOS) nitric oxide synthase were determined. METHODS: Isolated perfused guinea pig hearts underwent 30-min global ischemia and 120-min reperfusion (Control: CTL). The ethanol group (EtOH) received 2.5% ethanol in their drinking water for 6 wk. Anesthetic preconditioning was elicited by 10-min exposure to sevoflurane (1 minimum alveolar anesthetic concentration; 2%) in ethanol …