AJP-Heart and Circulatory Physiology Podcast

Mitochondrial Function in the Ischemic Human Heart

Assessment of cardiac mitochondrial function in patients with chronic ischemic heart disease is rarely undertaken, but ultimately these measurements provide the final word in our understanding of the pathology of myocardial bioenergetics. In this new podcast, Editor in Chief William Stanley interviews lead author Flemming Dela (University of Copenhagen) and expert Ethan Anderson (East Carolina University) about the clinical studies by Stride et al. Listen as we gain new insights into the challenges of obtaining samples from human ventricle tissue, and discuss the experimental hurdles faced by researchers in this field. Will the next steps uncover new ways to manipulate mitochondria to lessen ischemia injury? Listen and find out.

Nis Stride, Steen Larsen, Martin Hey-Mogensen, Christina Neigaard Hansen, Clara Prats, Daniel Steinbrüchel, Lars Køber, and Flemming Dela Impaired Mitochondrial Function in Chronically Ischemic Human Heart Am J Physiol Heart Circ Physiol, published online March 29, 2013, doi: 10.1152/ajpheart.00991.2012.

Atrial and Sinus Node Arrhythmias in Ankyrin-B Syndrome

How can one monogenic defect—a mutation of the structural protein ankyrin-B—give rise to multiple disparate phenotypes across the heart? The new work by Wolf et al examines this very question. Associate Editor Igor Efimov interviews lead author Thomas Hund (Ohio State University) and expert Natalia Trayanova (Johns Hopkins University) in our latest podcast, which explores the multi-scale computer model created by Hund and his colleagues to study ankyrin-B mutation and its effect on sinus node dysfunction. Does Hund make the case for using an integrative, rather than reductionist, approach to studying cardiac arrhythmias? Listen and learn.

Roseanne M. Wolf, Patric Glynn, Seyed Hashemi, Keyan Zarei, Colleen C. Mitchell, Mark E. Anderson, Peter J. Mohler, and Thomas J. Hund Atrial Fibrillation and Sinus Node Dysfunction in Human Ankyrin-B Syndrome: A Computational Analysis Am J Physiol Heart Circ Physiol, published online February 22, 2013, doi: 10.1152/ajpheart.00734.2012.

Liposomal Erythropoietin Protects the Heart

Reducing infarct size to prevent ischemic heart failure in patients with acute myocardial infarction is a known challenge for clinical cardiologists, and few drugs meet this challenge. In our new podcast Associate Editor Masafumi Kitakaze interviews lead author Shinya Minatoguchi (Gifu University Graduate School of Medicine, Gifu, Japan) and expert Tetsuji Miura (Sapporo Medical University School of Medicine, Sapporo, Japan) about the innovative new work by Yamada et al which used liposomal erythropoietin therapy to reduce infarct size in a rabbit heart model. Can this relatively non-invasive drug delivery method become an effective way to reduce infarct size in acute MI human patients? Listen now.

Yoshihisa Yamada, Hiroyuki Kobayashi, Masamitsu Iwasa, Shohei Sumi, Hiroaki Ushikoshi, Takuma Aoyama,
Kazuhiko Nishigaki, Genzou Takemura, Takako Fujiwara, Hisayoshi Fujiwara, Makoto Kiso, and Shinya Minatoguchi Postinfarct active cardiac-targeted delivery of erythropoietin by liposomes with sialyl Lewis X repairs infarcted myocardium in rabbits Am J Physiol Heart Circ Physiol, published online February 15, 2013, doi: 10.1152/ajpheart.00707.2012.

JAPANESE VERSION: Liposomal Erythropoietin Protects the Heart

NEW! In this JAPANESE language podcast, Associate Editor Masafumi Kitakaze interviews lead author Shinya Minatoguchi (Gifu University Graduate School of Medicine, Gifu, Japan) and expert Tetsuji Miura (Sapporo Medical University School of Medicine, Sapporo, Japan) about the innovative new work by Yamada et al which used liposomal erythropoietin therapy to reduce infarct size in a rabbit heart model. Can this relatively non-invasive drug delivery method become an effective way to reduce infarct size in acute MI human patients? Listen now.

Yoshihisa Yamada, Hiroyuki Kobayashi, Masamitsu Iwasa, Shohei Sumi, Hiroaki Ushikoshi, Takuma Aoyama,
Kazuhiko Nishigaki, Genzou Takemura, Takako Fujiwara, Hisayoshi Fujiwara, Makoto Kiso, and Shinya Minatoguchi Postinfarct active cardiac-targeted delivery of erythropoietin by liposomes with sialyl Lewis X repairs infarcted myocardium in rabbits Am J Physiol Heart Circ Physiol, published online February 15, 2013, doi: 10.1152/ajpheart.00707.2012.

DPP-IV Inhibitor Improves Survival in Murine Heart Failure

Can diabetes treatments also protect the heart? In our latest podcast we explore the work by Takahashi et al, which examined what a DPP-IV inhibitors will do at the level of the heart. Associate Editor Gary Lopaschuk interviews lead author Masanori Asakura (National Cerebral and Cardiovascular Center, Osaka, Japan) and expert Zam Kassiri (University of Alberta) about this exciting new work which pulls together aspects of metabolism, heart failure, anti-diabetic agents and cardioprotection. Listen and learn more.

Ayako Takahashi, Masanori Asakura, Shin Ito, Kyung-Duk Min, Kazuhiro Shindo, Yi Yan, Yulin Liao, Satoru Yamazaki, Shoji Sanada, Yoshihiro Asano, Hatsue Ishibashi-Ueda, Seiji Takashima, Tetsuo Minamino, Hiroshi Asanuma, Naoki Mochizuki, and Masafumi Kitakaze Dipeptidyl-Peptidase IV Inhibition Improves Pathophysiology of Heart Failure and Increases Survival Rate in Pressure-Overloaded Mice Am J Physiol Heart Circ Physiol, published online March 15, 2013, doi: 10.1152/ajpheart.00454.2012.

Coronary Vasoconstriction in Heart Failure Impairs Contractility

Can an abnormal metaboreflex activation causing coronary constriction help to explain the reduced ability of the heart to increase cardiac performance in heart failure patients during exercise? While the metaboreflex has been studied for decades, new research by Coutsos et al in a chronic dog model of heart failure gives fresh insights on how ventricular function is improved by relieving vasoconstriction and thus enhancing coronary blood flow. Associate Editor Fabio Recchia interviews lead author Donal O’Leary (Wayne State University) and expert Antonio Crisafulli (University of Cagliari, Italy) about this interesting work and its potential clinical impact on heart failure patients.

Matthew Coutsos, Javier A. Sala-Mercado, Masashi Ichinose, ZhenHua Li, Elizabeth J. Dawe, and Donal S. O'Leary Muscle Metaboreflex-Induced Coronary Vasoconstriction Limits Ventricular Contractility During Dynamic Exercise in Heart Failure Am J Physiol Heart Circ Physiol, published online January 25, 2013, doi: 10.1152/ajpheart.00879.2012.

Mitochondrial Calcium in mdx Myocytes

How is Ca2+ cycling in the heart altered in cardiomyopathy in Duchenne muscular dystrophy? Does a lack of the cytoskeletal protein dystrophin cause a perturbation in communication between L-type calcium channels and mitochondria? In our latest podcast on the work by Viola et al., Associate Editor Meredith Bond hosts a discussion with lead author Livia Hool (The University of Western Australia) and expert Angela Dulhunty (Australian National University). We examine the effect of disruption of the myocyte cytoskeleton in the mdx mouse model. We address the role of the myocyte cytoskeleton in regulating communication between plasma membrane and mitochondria, and we tackle potential clinical applications for muscular dystrophy patients. Listen now.

Helena M. Viola, Stefan M. K. Davies, Aleksandra Filipovska, and Livia C. Hool L-type Ca2+ channel contributes to alterations in mitochondrial calcium handling in the mdx ventricular myocyte Am J Physiol Heart Circ Physiol, published online January 18, 2013, doi: 10.1152/ajpheart.00700.2012.

Secondary SR Ca2+ Release and Arrhythmia Risk in Bradycardia

Our latest podcast explores the newly published article by Kim et al. In this work, lead author Guy Salama (University of Pittsburgh) and colleagues found that by prolonging action-potential duration, bradycardia may destabilize calcium and cause arrhythmia. Associate Editor Igor Efimov leads an engaging discussion with Salama and expert Steven Poelzing (Virginia Tech) about how intracellular calcium can affect cardiac electrophysiology, and through calcium-voltage coupling, can become the original source of arrhythmia. We also take a look at gender differences in remodeling and arrhythmogenesis, and the possible role estrogen may play in the susceptibility of the female heart to bradycardia-mediated arrhythmias.

Jong J. Kim, Jan Nemec, Rita Papp, Robert Strongin, Jonathan J Abramson, and Guy Salama Bradycardia alters Ca2+ dynamics which enhances dispersion of repolarization and arrhythmia risk Am J Physiol Heart Circ Physiol, published online January 11, 2013, doi: 10.1152/ajpheart.00787.2012.

G6PD Deficiency and Cardiovascular Disease

What can we learn from the most common enzyme deficiency in the world? Quite a lot, actually. G6PD deficiency has cascading effects on NADPH, reactive oxygen species production, and anti-oxidant reserves, all outlined in a comprehensive new Review article by Hecker et al. Associate Editor Ajay Shah interviews first author Peter Hecker (Washington University in St. Louis) as well as leading expert, and Associate Editor, Ronglih Liao (Brigham and Women's Hospital and Harvard Medical School) about compartmentalization, potential drug therapies, and where the study of G6PD deficiency will lead to next.

Peter A. Hecker, Jane A. Leopold, Sachin A. Gupte, Fabio A. Recchia, and William C. Stanley Impact of glucose-6-phosphate dehydrogenase deficiency on the pathophysiology of cardiovascular disease Am J Physiol Heart Circ Physiol, published online December 15, 2012, doi: 10.1152/ajpheart.00721.2012.

MSC-induced Cx43 Expression in Cardiomyocytes

We break it down for you: what really are the factors and mechanisms of cell replacement therapy? What are the mechanisms by which transplanted MSCs exert their paracrine effects? Associate Editor Ivor Benjamin interviews lead author Kathrin Banach (University of Illinois at Chicago) and expert Timothy Kamp (University of Wisconsin - Madison) about the recent work by Mureli et al, which has significant translational implications for cell therapy after ischemic injury. Listen and learn more..

Shwetha Mureli, Christopher P. Gans, Dan J. Bare, David L. Geenen, Nalin M. Kumar, and Kathrin Banach Mesenchymal Stem Cells Improve Cardiac Conduction by Up-Regulation of Connexin 43 Through Paracrine Signaling Am J Physiol Heart Circ Physiol, published online December 15, 2012, doi: 10.1152/ajpheart.00533.2012.