AJP-Heart and Circulatory Physiology Podcast

Electrophysiology of hiPSC-derived cardiomyocytes

The discovery of induced pluripotent stem (iPS) cells has allowed researchers to generate human cardiomyocytes from patients. Why is this important? Human iPS cells are useful for studying normal and diseased human cardiomyocytes and for discovering new drug therapies to treat cardiovascular disease. Until now, methods for generating cardiomyocytes from human iPS or ES cells were inconsistent and often unreliable. The recent article by Ma et al presents a new method to obtain a large quantity of cultured cardiac myocytes using embryoid body formation and blasticidin selection techniques resulting in more than 98% purity from human iPS cell lines. Associate Editor Junichi Sadoshima talks with authors Craig January (University of Wisconsin – Madison) and Brad Swanson (Cellular Dynamics International), along with leading expert Diego Fraidenraich (University of Medicine and Dentistry, New Jersey), about this groundbreaking research and its many potential applications.

Junyi Ma, Liang Guo, Steve J Fiene, Blake D Anson, James A Thomson, Timothy J. Kamp, Kyle L Kolaja, Bradley J Swanson, and Craig T. January. High Purity Human Induced Pluripotent Stem Cell (hiPSC) Derived Cardiomyocytes: Electrophysiological Properties of Action Potentials and Ionic Currents. Am J Physiol Heart Circ Physiol, published ahead of print September 2, 2011, doi:10.1152/ajpheart.00694.2011.

Carotid baroreflex responsiveness is impaired in normotensive African American men

It almost goes without saying that human beings are genetically diverse and that diseases develop differently, and at different rates, across various racial groups in the human population. Case in point: African Americans are predisposed to developing far deadlier forms of hypertension earlier in life than other racial group counterparts. Associate Editor Irving Zucker talks with lead author David Keller (University of Texas Arlington) and expert Peter Raven (University of North Texas Health Science Center) about the work of Holwerda et al, which studied the possibility of the baroreflex contributing to the development of hypertension in African American males.

Seth W. Holwerda, Diana Fulton, Wendy L. Eubank, and David M. Keller. Carotid Baroreflex Responsiveness is Impaired in Normotensive African American Men. Am J Physiol Heart Circ Physiol, October 2011 301:H1639-H1645; published ahead of print August 12, 2011, doi:10.1152/ajpheart.00604.2011.

Shedding of the Glycocalyx and Capillary Hemodynamics

We know that the endothelial surface is coated with glycocalyx. But why should we be concerned about the effects of shedding the glycocalyx on microvascular hemodynamics? Editor in Chief William C. Stanley talks with senior author Herbert Lipowsky (Pennsylvania State University) and leading expert Jos A. Spaan (University of Amsterdam) about the unique model presented in the article by Lipowsky et al that mimics aspects of acute vascular inflammation and investigates how shedding of the glycocalyx impacts many pathologies including diabetes.

Herbert H. Lipowsky, Lujia Gao, and Anne Lescanic. Shedding of the Endothelial Glycocalyx in Arterioles, Capillaries and Venules and its Effect on Capillary Hemodynamics During Inflammation. Am J Physiol Heart Circ Physiol, published ahead of print September 16, 2011, doi:10.1152/ajpheart.00803.2011.

DHEA inhibits the Src/STAT3 constitutive activation

Pulmonary hypertension affects millions of patients with increasing prevalence each year, and clinical treatments are still in their infancy. In our latest podcast, Associate Editor Leon de Windt talks with senior author Sebastien Bonnet (Universite Laval) and leading expert Laura Gonzalez Bosc (University of New Mexico) about the article by Paulin et al, which reports the first demonstration of DHEA blocking two major transcription factors—STAT3 and NFAT. Is DHEA, a commercially available natural steroid hormone and antioxidant, the newest entry point for pharmacological intervention and treatment of pulmonary hypertension? Listen in and find out.

Roxane Paulin, Jolyane Meloche, Maria Helena Jacob, Malik Bisserier, Audrey Courboulin, and Sebastien Bonnet. Dehydroepiandrosterone inhibits the Src/STAT3 constitutive activation in pulmonary arterial hypertension. Am J Physiol Heart Circ Physiol, published ahead of print September 2, 2011, doi:10.1152/ajpheart.00654.2011.

Alignment of SR-mitochondrial junctions and contact points

In our latest podcast we explore the connections between the sarcoplasmic reticulum and the mitochondria within calcium regulation during signaling contractile function and regulation of mitochondrial metabolism. Associate Editor Gary Lopaschuk interviews senior author Gyorgy Csordas (Thomas Jefferson University) and leading expert Pal Pacher (National Institutes of Health), seeking to explore a central question in the work by Garcia-Perez et al—how are the SR and the mitochondria communicating with each other?

Cecilia Garcia-Perez, Timothy G. Schneider, Gyorgy Hajnoczky, and Gyorgy Csordas. Alignment of sarcoplasmic reticulum-mitochondrial junctions with mitochondrial contact points. Am J Physiol Heart Circ Physiol, published online ahead of print August 19, 2011, doi:10.1152/ajpheart.00397.2011.

Physiology: Found in Translation

Did physiology get lost in the genomics explosion? Our experts think not. Rather they champion the reemergence of physiology as the essential discipline required to make sense of the “omics” revolution. Join Editor in Chief William Stanley, leading experts Michael Joyner (Mayo Clinic) and Shawn Bender (University of Missouri), and authors Peter Wagner (University of California, San Diego) and David Paterson (University of Oxford), as they discuss how insights from the “omics” disciplines depend on physiology for translation into new biological concepts and clinical applications.

Peter D. Wagner and David J. Paterson. Physiology: Found in Translation Am J Physiol Heart Circ Physiol, published online ahead of print July 1, 2011, doi:10.1152/ajpheart.00649.2011.

Shear- and side-specific mRNAs and miRNAs in HAVECs

In our latest podcast, we investigate aortic valve disease and potential therapeutic interventions other than valvular replacement. Associate Editor Ivor Benjamin interviews authors Hanjoong Jo and Casey Holliday (Emory University) as well as leading expert Jordan Miller (Mayo Clinic) about the recently published article by Holliday et al, which probes the role of endothelial cells in the aortic valve and explores our understanding of mechanosensitive microRNAs responding to shear stress.

 

Casey J. Holliday, Randall F. Ankeny, Hanjoong Jo, and Robert M. Nerem.Discovery of shear- and side-specific mRNAs and miRNAs in human aortic valvular endothelial cells Am J Physiol Heart Circ Physiol published ahead of print June 24, 2011, doi:10.1152/ajpheart.00117.2011.

The rate of oxygen loss from mesenteric arterioles is not unusually high

Most physiologists would probably agree that delivery of oxygen to tissues is the single most important function of the cardiovascular system. And, most would assign this task to the capillaries. Surprisingly however, some studies have suggested a major role for arterioles instead. In our latest podcast Associate Editor W. Gil Wier interviews senior author Roland Pittman (Virginia Commonwealth University) and leading expert David Poole (Kansas State University) about the work of Golub et al, which provides some compelling new data on the issue, and also a reminder about the importance of critical evaluation of methodology.

 

Aleksander S. Golub, Bjorn K. Song, and Roland N. Pittman. The rate of oxygen loss from mesenteric arterioles is not unusually high Am J Physiol Heart Circ Physiol, published online ahead of print June 17, 2011, doi:10.1152/ajpheart.00353.2011.

Understanding Guyton's Venous Return Curves

For fifty years, Guyton's venous return curves and their interpretation, presented in virtually every heart physiology text, have instructed as much as puzzled many students. Senior Associate Editor David Kass, leading expert John Tyberg (University of Calgary), and authors Daniel Beard (Medical College of Wisconsin) and Eric Feigl (University of Washington) set the record straight on how to understand basic cardiovascular physiology of the circulation, venous return into the heart, and the control of cardiac output. Medical students, physiologists, and physicians take note:  getting the pressure-volume relationship right has never been more important.

 

Daniel A. Beard and Eric O. Feigl. Understanding Guyton's Venous Return Curves Am J Physiol Heart Circ Physiol, published online ahead of print June 10, 2011; doi:10.1152/ ajpheart.00228.2011.

Biochemical and myofilament responses of the right ventricle to severe pulmonary hypertension

A novel and unique large animal model illuminates why we should focus, for a change, on right ventricular cardiac disease and some of the changes that occur during development of right ventricular failure and pulmonary hypertension. Associate Editor Meredith Bond interviews authors Lori Walker and Peter Buttrick (both University of Colorado Denver), as well as leading expert JP Jin (Wayne State University) about this innovative study presented in the article by Walker et al.

Lori A. Walker, John Stephen Walker, Amelia Glazier, R. Dale Brown, Kurt R. Stenmark, and Peter M. Buttrick.Biochemical and myofilament responses of the right ventricle to severe pulmonary hypertension Am J Physiol Heart Circ Physiol, published online ahead of print May 27, 2011; doi:10.1152/ajpheart.00249.2011.