AJP-Heart and Circulatory Physiology Podcast

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.

Sex Differences and Vascular Reactivity to Mental Stress

Do men and women handle mental stress differently? What role do sex differences play in the transduction of muscle sympathetic nerve activity (MSNA) into vascular tone during stress? Associate Editor Irving Zucker explores the recent work by Yang et al in our new podcast interview with lead author Jason Carter (Michigan Technological University) and expert Nisha Charkoudian (U.S. Army Research Institute of Environmental Medicine) in a stimulating conversation germane to the wave of research on sex differences in cardiovascular science. Listen now.

Huan Yang, Thomas Drummer, and Jason R. Carter Sex differences in sympathetic neural and limb vascular reactivity to mental stress in humans Am J Physiol Heart Circ Physiol, published online November 30, 2012, doi: 10.1152/ajpheart.00688.2012.

Endothelin-1 and Exercise

How can we tame the sleeping giant of excess skeletal muscle blood flow during exercise? In our latest podcast we expand our understanding of the role endothelin-1 plays in regulating skeletal muscle blood flow during whole body, as well as targeted, exercise in healthy patients. Consulting Editor David Gutterman leads this interesting conversation with author Walter Wray (University of Utah) and expert Kevin Dellsperger (University of Missouri-Columbia) about the recent work by Barrett-O’Keefe et al. What are the possibilities for targeting the endothelin-1 pathway in disease states? Listen now.

Zachary Barrett-O'Keefe, Stephen J. Ives, Joel Douglas Trinity, Richard Garrett Morgan, Matthew Jordan Rossman, Anthony J. Donato, Sean Runnels, David E. Morgan, Benjamin S. Gmelch, Amber D. Bledsoe, Russell S. Richardson, and D. Walter Wray Taming the "Sleeping Giant": The Role of Endothelin-1 in the Regulation of Skeletal Muscle Blood Flow and Arterial Blood Pressure during Exercise Am J Physiol Heart Circ Physiol, published online October 26, 2012, doi:10.1152/ajpheart.00603.2012.

MMPs: Milestones, Myths, and (Mis)Perceptions

So you thought that the role of matrix metalloproteinases (MMPs) in myocardial remodeling had been all worked out? Well, it's not so simple. The latest Review article by Iyer et al debunks myths and demystifies perceptions surrounding MMPs and their role in regulating the extracellular matrix and cardiac structure. In our new podcast, Editor in Chief William Stanley interviews lead author Merry Lindsey (University of Texas Health Science Center San Antonio) and expert Loren Wold (The Research Institute at Nationwide Children's Hospital) about the work by Lindsey and others in the MMP/TIMP field. Listen now to discover more.

Rugmani Padmanabhan Iyer, Nicolle L. Patterson, Gregg B. Fields, and Merry L. Lindsey The history of matrix metalloproteinases: milestones, myths, and misperceptions Am J Physiol Heart Circ Physiol, published online August 17, 2012, doi: 10.1152/ajpheart.00577.2012.

Right Ventricular Arrhythmogenic Remodeling in Heart Failure

Can translational research using donated human hearts uncover the mechanism behind cardiac sudden death in heart failure patients? In our latest podcast, Editor in Chief William Stanley interviews renowned researcher Igor Efimov (Washington University) and global expert Kenneth Laurita (Case Western Reserve University) about the latest work by Lou et al. demonstrating enhanced dispersion of repolarization in right ventricles obtained from heart failure patients.

Qing Lou, Deborah L Janks, Katherine Holzem, Di Lang, Birce Onal, Christina M Ambrosi, Vadim V Fedorov, I-Wen Wang, and Igor R. Efimov Right Ventricular Arrhythmogenesis in Failing Human Heart: The Role of Conduction and Repolarization Remodeling Am J Physiol Heart Circ Physiol, published online October 5, 2012, doi: 10.1152/ajpheart.00457.2012.

Sildenafil and Exercise Muscle Oxygenation in Chronic Heart Failure

What is arguably the most famous drug side effect of all time? Back in 1992 sildenafil, a PDE5 inhibitor, was ineffective for treatment of ischemic heart disease, but went on to become a blockbuster drug for erectile dysfunction. In our latest podcast Senior Associate Editor David A. Kass interviews lead author Alberto Neder and expert David Poole about the recent work by Sperandio et al, which demonstrates how sildenafil can improve the cardiovascular response to exercise in heart failure patients. Will current clinical trials show that sildenafil benefits cardiac remodeling and vascular dysfunction in heart failure?

Priscila A Sperandio, Mayron F Oliveira, Miguel K Rodrigues, Danilo C Berton, Erika Treptow, Luiz E Nery, Dirceu R Almeida, and J. Alberto Neder Sildenafil Improves Microvascular O2 Delivery-to-Utilization Matching and Accelerates Exercise O2 Uptake Kinetics in Chronic Heart Failure Am J Physiol Heart Circ Physiol, published online September 28, 2012, doi:10.1152/ajpheart.00435.2012.

Oxidative Stress and Hemodynamics in Heart Failure

Why are heart failure patients exercise intolerant? Is it due to oxidative stress? In our latest podcast, Editor in Chief William Stanley talks with first author Melissa Witman (University of Utah) about her study that assessed the impact of an “antioxidant cocktail” on central and peripheral hemodynamics during exercise in heart failure patients. Carlos Negrao (University of Sao Paulo) lends his expert opinion in this lively conversation. Listen and learn.

Melissa A. H. Witman, John McDaniel, Anette S. Fjeldstad, Stephen J. Ives, Jia Zhao, Jose N. Nativi, Josef Stehlik, D. Walter Wray, and Russell S. Richardson A Differing Role of Oxidative Stress in the Regulation of Central and Peripheral Hemodynamics during Exercise in Heart Failure Am J Physiol Heart Circ Physiol, published online September 7, 2012, doi: 10.1152/ajpheart.00568.2012.