AJP-Heart and Circulatory Physiology Podcast

Exercise Training Improves Metabo and Mechanoreflex Control in Heart Failure

The so called “exercise pressor reflex” is enhanced in chronic heart failure and drives sympathetic nerve activity during exercise. While exercise training can impact the sensitivity of this reflex, the molecular mechanisms that are at play remain unclear. Listen as Editor-in-Chief Irving H. Zucker interviews lead author Carlos Negrao (University of Sao Paulo) and expert Vaughan Macefield (University of Western Sydney) about the exciting new work by Antunes-Correa et al., who found that exercise training in chronic heart failure patients decreased the muscle mechanoreflex control of sympathetic nerve activity. Did Negrao and colleagues find that molecular abnormalities in skeletal muscle underlie abnormal muscle sympathetic nerve activity in humans with heart failure? Are these effects reversible with exercise training? Listen and learn more.

Ligia M. Antunes-Correa, Thais S. Nobre, Raphaela V. Groehs, Maria-Janieire N.N. Alves, Tiago Fernandes, Gisele K. Couto, Maria Urbana P.B. Rondon, Patricia Alves de Oliveira, Marta Lima, Wilson Mathias Jr., Patricia C. Brum, Charles Mady, Dirceu R. Almeida, Luciana Venturini Rossoni, Edilamar Menezes de Oliveira, Holly R. Middlekauff, Carlos Eduardo Negrao Molecular Basis for the Improvement in Muscle Metaboreflex and Mechanoreflex Control in Exercise-Trained Humans with Chronic Heart Failure Am J Physiol Heart Circ Physiol, published December 1, 2014. DOI: 10.1152/ajpheart.00136.2014.

Mitochondrial Depolarization and Electrophysiology

What is the relationship between cardiac mitochondrial metabolism and the mitochondrial membrane potential? Listen as Associate Editor Gary Lopaschuk interviews lead author Matthew Sulkin (Washington University), and expert Elaine Wan (Columbia University) about the innovative work by Sulkin and colleagues combining two different optical mapping techniques. What did the authors discover when they looked directly at the mitochondrial membrane potential during ischemia-reperfusion, and how might this inform potential therapies for ventricular arrhythmias? Listen and learn more…

Matthew S. Sulkin, Bas J. Boukens, Megan Tetlow, Sarah R. Gutbrod, Fu Siong Ng, Igor R. Efimov Mitochondrial depolarization and electrophysiological changes during ischemia in the rabbit and human heart Am J Physiol Heart Circ Physiol, published October 15, 2014.
DOI: 10.1152/ajpheart.00437.2014.

Angiogenic Response to Exercise and Resveratrol

Can the polyphenol antioxidant resveratrol, commonly found in red wine, augment the angiogenic effects of exercise training? Guest Editor Nisha Charkoudian (U.S. Army Research Institute of Environmental Medicine) interviews lead author Lasse Gliemann (University of Copenhagen) and expert Michael Joyner (Mayo Clinic) about the fascinating, and somewhat surprising, work by Gliemann and colleagues combining exercise training in older men with resveratrol supplementation in pill form. With so much media hype focused on the possibility of a so-called "exercise pill," we break down the myths and focus on the facts in this engaging podcast. Brush off your bicycle helmet, and listen now.

Lasse Gliemann, Jesper Olesen, Rasmus Sjørup Biensø, Jakob Friis Schmidt, Thorbjorn Akerstrom, Michael Nyberg, Anna Lindqvist, Jens Bangsbo, Ylva Hellsten Resveratrol modulates the angiogenic response to exercise training in skeletal muscles of aged men Am J Physiol Heart Circ Physiol, published October 15, 2014. DOI: 10.1152/ajpheart.00168.2014.

Dantrolene suppresses Ca2+ sparks and Ca2+ waves

In this podcast we highlight the recent study by Domeier and colleagues, which looked for a way to pharmacologically restore proper function of the ryanodine receptor with advancing age. Did they find it? Editor in Chief Dr. Irving Zucker interviews lead author Timothy Domeier (The University of Missouri School of Medicine) and expert Eric Sobie (Mount Sinai School of Medicine) about this fascinating study investigating whether ryanodine receptor mediated calcium release in the aged heart was altered by dantrolene. In fact, Domeier and colleagues did find that dantrolene provided a protective effect against pro-arrhythmic calcium sparks and calcium waves in diastole. Hear about this finding and much more by clicking play below.

Timothy L. Domeier, Cale J. Roberts, Anne K. Gibson, Laurin M. Hanft, Kerry S. McDonald, Steven S. Segal Dantrolene suppresses spontaneous Ca2+ release without altering excitation-contraction coupling in cardiomyocytes of aged mice Am J Physiol Heart Circ Physiol, published September 15, 2014. DOI: 10.1152/ajpheart.00287.2014.

Noninvasive Longitudinal Measurements of [Ca2+] in Arterioles of Hypertensive Optical Biosensor Mice

Have noninvasive calcium signaling measurement methods turned a new corner? Yes, according to a unique new study by Mauban et al. Associate Editor Nancy Kanagy interviews senior author W. Gil Wier (University of Maryland School of Medicine) and leading expert Mark Nelson (University of Vermont) about the work by Wier and colleagues, which measured intracellular levels of calcium noninvasively in the same animal over a period of several weeks. How? Wier and co-authors ingeniously immobilized the mouse ear, enabling the use of a FRET-based ratiometric calculation of actual intracellular calcium levels in vascular cells inside the living animal. Does this innovative methodology launch new possibilities for evaluating calcium signaling changes during disease development? Listen and find out.

Joseph R. H. Mauban, Seth T. Fairfax, Mark A. Rizzo, Jin Zhang, Withrow Gil Wier A method for noninvasive longitudinal measurements of [Ca2+] in arterioles of hypertensive optical biosensor mice Am J Physiol Heart Circ Physiol, published July 15, 2014. DOI: 10.1152/ajpheart.00182.2014.

DDR2 Deletion in the Heart

What happens to the left ventricle and cardiac fibroblasts when DDR2 (Discoidin Domain Receptor 2) is deleted? Deputy Editor Merry Lindsey interviews lead author Randy Cowling (University of California San Diego) and expert Angelo Calderone (Montreal Heart Institute/Universite de Montreal) about the novel work by Cowling and colleagues, which explored the surprising finding that DDR2 deletion resulted in less densely packed collagen that altered myocyte contractility. Does this work provide a stepping stone to deeper investigation of the intricacies of collagen deposition by cardiac fibroblasts? Given the “plasticity” of fibroblast phenotypes, what are the implications of pathological stimuli— for example, post-myocardial infarction? Listen and learn more.

Randy T Cowling, Seon Ju Yeo, In Jai Kim, Joong Il Park, Yusu Gu, Nancy D. Dalton, Kirk L. Peterson, Barry H Greenberg Discoidin Domain Receptor 2 (DDR2) Germline Gene Deletion Leads to Altered Heart Structure and Function in the Mouse Am J Physiol Heart Circ Physiol, published online July 3, 2014. DOI: 10.1152/ajpheart.00142.2014.

TIMP-4 and Left Ventricular Pressure Overload

How does TIMP-4 really behave in the myocardium, and what is its role in the pressure overload response to transverse aortic constriction? In this engaging author interview, Deputy Editor Merry Lindsey talks with lead author Francis Spinale (University of South Carolina School of Medicine and WJB Dorn VA Medical Center) and expert Zamaneh Kassiri (University of Alberta) about the work by Yarbrough et al, which surprisingly showed that inducing TIMP-4 in the setting of pressure overload may be beneficial. Have Spinale and colleagues opened the door to a sea-change in the current canonical thinking of TIMP roles? Listen and find out.

William M. Yarbrough, Catalin F. Baicu, Rupak Mukherjee, An O. Van Laer, William T. Rivers, Richard A. McKinney, Corey B. Prescott, Robert E. Stroud, Parker D. Freels, Kia N. Zellars, Michael R. Zile, Francis G. Spinale Cardiac Restricted Overexpression Or Deletion Of Tissue Inhibitor Of Matrix Metalloproteinase-4 Am J Physiol Heart Circ Physiol, published online July 3, 2014. DOI: 10.1152/ajpheart.00063.2014.

Deformation Causes Vascular Alignment During Angiogenesis

What does “changing the boundary conditions” mean? In our latest author interview, Deputy Editor Dr. Merry Lindsey asks lead author Dr. Jeffrey Weiss (University of Utah) this very question about his innovative new work exploring the relationship between tissue mechanics and angiogenesis. Expert Hai-Chao Han (University of Texas at San Antonio) lends his insight into the importance of studying the mechanics of blood vessel formation. Will the work by Underwood et al, which elegantly blends computational and biological approaches, someday lead to new experimental applications, such as pre-aligned microvasculatures for engineered tissue constructs? Listen and learn.

Clayton J. Underwood, Lowell T. Edgar, James B. Hoying, Jeffrey A. Weiss Cell-generated traction forces and the resulting matrix deformation modulate microvascular alignment and growth during angiogenesis Am J Physiol Heart Circ Physiol, published July 15, 2014. DOI: 10.1152/ajpheart.00995.2013.

Wave Potential and the One-Dimensional Windkessel

While wave separation analysis is considered the gold standard for assessing pressure and flow waves in the arterial system, how do we account for self-cancelling flow waves during diastole? In this podcast Associate Editor Dr. Masafumi Kitakaze interviews lead author Jonathan Mynard (Murdoch Children’s Research Institute, Australia) and expert Berend Westerhof (Edwards Lifesciences BMEYE, Netherlands) about the innovative work by Mynard and co-author Joseph Smolich, which used mathematical models and experimental studies in sheep to discover the novel concepts of wave potential and the one-dimensional windkessel. With attention now being paid to the origin and behavior of self-cancelling diastolic waves, we may be poised to better understand the relationship between pressure and flow in cardiovascular health and disease states. Listen now and learn more.

Jonathan P Mynard , Joseph J. Smolich Wave potential and the one-dimensional windkessel as a wave-based paradigm of diastolic arterial hemodynamics Am J Physiol Heart Circ Physiol, published May 30, 2014. DOI: 10.1152/ajpheart.00293.2014.

Aromatase Modulates Cardiac Ischemic Stress Response

Beyond vascular effects, can estrogen produced in the heart have an influence on cardiac function? Is the local action of aromatase conversion of testosterone to estrogen important for the stressed heart? Listen as Guest Editor Dr. Virginia Miller interviews lead author Lea Delbridge (University of Melbourne) and expert Fred Naftolin (New York University) about the exciting new work by Bell et al showing aromatase expression in the heart at both the messenger and protein level. Given that the human heart is sexually dimorphic, and that this may extend past development to actual function, what insightful differences did the authors find in male and female aromatase transgenic mouse hearts? Listen now.

James R. Bell, Gabriel B. Bernasochi, Upasna Varma, Wah Chin Boon, Stuart J. Ellem, Gail P. Risbridger, Lea M. D. Delbridge Aromatase transgenic upregulation modulates basal cardiac performance and the response to ischemic stress in male mice Am J Physiol Heart Circ Physiol, published May 1, 2014. DOI: 10.1152/ajpheart.00012.2014.