AJP-Heart and Circulatory Physiology Podcast

Assessment of Diastolic Function

Listen as Deputy Editor Merry Lindsey (University of Nebraska Medical Center) interviews authors Leslie Ogilvie and Jeremy Simpson (University of Guelph) and expert Michael Czubryt (University of Manitoba) about the recent Review by Ogilvie et al. on the importance of evaluating best practices in the hemodynamic assessment of diastolic function for animal models. With significant clinical focus on the role diastolic dysfunction plays in heart failure with preserved ejection fraction (HFpEF), cardiac fibrosis, and diabetes, there is no better time to examine diastolic functional assessments in experimental models. “Diastolic function has emerged as being equally important to systolic function in the overall ability of the heart to function as a pump,” explains Simpson. We discuss rodent models of human diastolic dysfunction in the setting of HFpEF, and understanding diastolic function in terms of its two phases—relaxation and filling. What recommendations do Ogilvie and Simpson make for handling the inherent limitations of software-based algorithms? Listen and learn more.

 

Leslie M. Ogilvie, Brittany A. Edgett, Jason S. Huber, Mathew J. Platt, Hermann J. Eberl, Sohrab Lutchmedial, Keith R. Brunt, Jeremy A. Simpson Hemodynamic assessment of diastolic function for experimental models Am J Physiol Heart Circ Physiol, published April 21, 2020. DOI: doi.org/10.1152/ ajpheart.00705.2019

Race, Blood Pressure, and Microvascular Function

Does pre-hypertension, or Stage 1 hypertension, have adverse effects on the microvasculature and the ability of blood vessels to vasodilate? In this episode, Associate Editor Nisha Charkoudian (U.S. Army Research Institute of Environmental Medicine) interviews lead author Brett Wong (Georgia State University) and expert Anna Stanhewicz (University of Iowa) about the new study by Wong and co-authors, in which a local heating protocol on the skin was used to investigate whether race and/or blood pressure affect sensory nerve function. The authors found that both sensory nerve function and microvascular nitric oxide function were reduced in pre-hypertensive non-Hispanic black study participants compared to non-Hispanic white study participants. Even in the absence of overt cardiovascular disease, the work by Wong and co-authors detected changes in the mechanisms controlling blood flow. How do the racial differences observed in this study challenge the “one size fits all” concept of preventative cardiovascular healthcare? Listen now.

 

Brett J. Wong, Casey G. Turner, James T. Miller, Demetria C. Walker, Yesser Sebeh, Matthew J. Hayat, Jeffrey S. Otis, Arshed A. Quyyumi Sensory nerve-mediated and nitric oxide-dependent cutaneous vasodilation in normotensive and prehypertensive non-Hispanic blacks and whites Am J Physiol Heart Circ Physiol, published July 14, 2020. DOI: doi.org/10.1152/ajpheart.00177.2020

Behind the Bench Episode 5

In this episode we take a look behind Behind the Bench, and turn the tables to interview the interviewers. Editor-in-Chief Dr. Irv Zucker (University of Nebraska Medical Center) talks with Dr. Lisandra de Castro Bras (East Carolina University) and Dr. Jonathan Kirk (Loyola University Chicago), our Behind the Bench podcast hosts. How did they both get started in science? What is their best advice to trainees launching their own careers in physiology? And how did this whole “Behind the Bench” podcast come about in the first place? So many questions. Let’s dive in.

 

Smoking Effects on Ventricular Repolarization

We know that smoking increases the risk of sudden cardiac death, which is linked to changes in ventricular repolarization. Is there a difference in sudden cardiac death risk between smoking tobacco cigarettes vs. e-cigarettes? Associate Editor Nisha Charkoudian (U.S. Army Research Institute for Environmental Medicine) interviews lead author Holly Middlekauff (University of California Los Angeles) and content expert Marmar Vaseghi (University of California Los Angeles) about the new study by Ip et al. In this study, the authors compared electrocardiogram indices of ventricular repolarization in tobacco smokers before and after smoking a tobacco cigarette, as well as e-cigarette vapers before and after smoking an e-cigarette—once with and once without nicotine. Acute nicotine intake was the same among both types of smokers. However, three ECG indices of repolarization were significantly prolonged in tobacco smokers after smoking, whereas one of three indices was prolonged in e-cigarette smokers after vaping. What do these findings indicate about the sudden cardiac death risk of e-cigarettes compared to tobacco cigarettes? Does the e-cigarette rate of nicotine delivery have an impact on physiological effects? Listen now to learn how to present an evidence-based argument the next time a friend (or your child) tells you e-cigarettes are “safer” than smoking.

 

Michelle Ip, Evangelos Diamantakos, Kacey Haptonstall, Yasmine Choroomi, Roya S. Moheimani, Kevin Huan Nguyen, Elizabeth Tran, Jeffrey Gornbein, Holly R. Middlekauff Tobacco and electronic cigarettes adversely impact ECG indexes of ventricular repolarization: implication for sudden death risk  Am J Physiol Heart Circ Physiol, published April 21, 2020. DOI: doi.org/10.1152/ajpheart.00738.2019

PTSD and Sympathetic Action Potential Discharge Pattern

Women develop post-traumatic stress disorder (PTSD) at twice the rate of men, and women with PTSD are at higher risk for developing hypertension. Yet little research has been done to date investigating the mechanisms mediating the link between PTSD and cardiovascular disease in women. The study by Yoo et al. seeks to change that. Associate Editor Donal O’Leary (Wayne State University School of Medicine) interviews lead author Qi Fu (The Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas) and expert Adam Case (University of Nebraska Medical Center) about the groundbreaking and clinically-relevant study by Fu and co-authors. The authors showed for the first time that women with PTSD had a greater pressor response during the cold pressor test compared with healthy women. What insights did Fu and collaborators uncover when they compared results from traditional methods to quantify integrated nerve signals, and a novel wavelet-based technique used to identify differences in MSNA responses to cold pressor test between women with PTSD and healthy women? Do Fu and Case anticipate that the current COVID-19 pandemic, while undeniably tragic, may eventually open new avenues of discovery for how women with PTSD differ from healthy counterparts and men? Listen and learn.

 

Jeung-Ki Yoo, Mark B. Badrov, Mu Huang, Ryan A. Bain, Raymond P. Dorn, Elizabeth H. Anderson, Jessica L. Wiblin, Alina Suris, J. Kevin Shoemaker, Qi Fu Abnormal sympathetic neural recruitment patterns and hemodynamic responses to cold pressor test in women with posttraumatic stress disorder Am J Physiol Heart Circ Physiol, published April 27, 2020. DOI: 10.1152/ajpheart.00684.2019

Behind the Bench Episode 4

In this episode of Behind the Bench with AJP-Heart and Circ hosted by Lisandra de Castro Bras (East Carolina University) and Jonathan Kirk (Loyola University Chicago), we talk with Charlotte Usselman, Assistant Professor in Kinesiology and Physical Education at McGill University. Charlotte’s recently published article is a culmination of research that began in the summer of 2016 during her post-doc at the John B. Pierce Laboratory at Yale School of Medicine. One year into the project, Charlotte was offered a position at McGill, which she postponed for 6 months to finish collecting data at Yale. In 2018, she focused heavily on getting her new lab up and running, and did not focus on her preeclampsia research. Charlotte’s story is living proof that things don’t always go as planned, much like having a preeclamptic pregnancy. Sometimes our lives outside of work are hard, even painful, and this certainly informs how we move forward personally and professionally. But a collision of timing can sometimes result in unexpected success. How? Listen.

 

Charlotte W. Usselman, Tessa E. Adler, Yasmine Coovadia, Cheryl Leone, Michael J. Paidas, Nina S. Stachenfeld A recent history of preeclampsia is associated with elevated central pulse wave velocity and muscle sympathetic outflow Am J Physiol Heart Circ Physiol, published March 3, 2020. DOI: doi.org/10.1152/ ajpheart.00578.2019

Guidelines for Animal Exercise and Training Protocols

What are the best practices for animal models of exercise training? Associate Editor Mario Delmar (New York University) kickstarts a conversation with expert physiologists David Poole (Kansas State University), Timothy Musch (Kansas State University), Steven Copp (Kansas State University), Michael Sturek (Indiana University), Donal O’Leary (Wayne State University), and our own Editor in Chief Irv Zucker (University of Nebraska Medical Center) about the new Guidelines in Cardiovascular Research article by Poole et al. This landmark Guidelines article is designed to provide researchers with comprehensive information as they navigate selecting the most appropriate animal species and exercise paradigm to use in their exercise studies. As Tim Musch points out, “Exercise tests are many times the best strategy for determining the presence and severity of disease.” As the authors explain, animal models offer researchers the ability to control for disease severity and duration, confounding drug treatments, invasive procedures, as well as acute and chronic exercise interventions. We cover rat, mouse, dog, pig, and rabbit exercise training, and discuss everything from which incentive (dark chocolate or cocoa puffs?) rats prefer to thoroughbred racehorses! Listen now.

 

David C. Poole, Steven W. Copp, Trenton D. Colburn, Jesse C. Craig, David L. Allen, Michael Sturek, Donal S. O’Leary, Irving H. Zucker, Timothy I. Musch Guidelines for animal exercise and training protocols for cardiovascular studies Am J Physiol Heart Circ Physiol, published April 21, 2020. DOI: doi.org/10.1152/ajpheart.00697.2019

TPPU-Reversible Alterations of Renin Angiotensin System

High fructose consumption is associated with metabolic syndrome, but the mechanisms are not well understood. Listen as Associate Editor Fabio Recchia (Temple University and Scuola Superiore Sant'Anna) interviews lead author An Huang (New York Medical College) and content expert Zsolt Bagi (Medical College of Georgia) about the new study by Froogh et al, which used an animal model to test the hypothesis that a high fructose diet elicits a chymase-dependent increase in angiotensin II production and oxidative stress. In this technical tour de force of a podcast, we unpack the complexities of EET as a protective factor against oxidative stress. Listen as our experts discuss metabolic syndrome in the context of COVID-19, as well as the potential clinical translation of chymase and soluble epoxide hydrolase as therapeutic targets for the treatment of metabolic syndrome.

 

Ghezal Froogh, Sharath Kandhi, Roopa Duvvi, Yicong Le, Zan Weng, Norah Alruwaili, Jonathan O. Ashe, Dong Sun, An Huang The contribution of chymase-dependent formation of ANG II to cardiac dysfunction in metabolic syndrome of young rats: roles of fructose and EETs Am J Physiol Heart Circ Physiol, published April 2, 2020. DOI: doi.org/10.1152/ ajpheart.00633.2019

Leg Heating and Neural Control in Aging

We know that blood pressure increases with age, and that a large part of the global population takes at least one blood pressure lowering medication. Could acute leg heating be used as a non-pharmacological therapy to lower blood pressure in aged adults? In our latest podcast, Associate Editor Nisha Charkoudian (U.S. Army Research Institute of Environmental Medicine) interviews lead author Steven Romero (University of North Texas Health Science Center) and expert Charlotte Usselman (McGill University) about the new study by Engelland et al. Romero and co-authors examined the neurovascular mechanisms through which acute isolated leg heating reduced arterial blood pressure in an older cohort of healthy adults compared to healthy younger adults. While sympathetic nerve activity did not differ from preheat to recovery in aged adults, this group experienced a marked reduction in blood pressure. Does this response vary by sex or is neurovascular transduction altered on an acute time scale? Listen to find out the answers to these questions as we cover this hot topic.

 

Rachel E. Engelland, Holden W. Hemingway, Olivia G. Tomasco, Albert H. Olivencia-Yurvati, Steven A. Romero Neural control of blood pressure is altered following isolated leg heating in aged humans Am J Physiol Heart Circ Physiol, published April 2, 2020. DOI: doi.org/10.1152/ajpheart.00019.2020

COVID-19, ACE2 and the Cardiovascular Consequences

While the global community struggles to cope with the COVID-19 pandemic, our latest episode investigates what role the angiotensin-converting enzyme 2 (ACE2) plays in the internalization of the novel SARS coronavirus SARS-CoV-2. Editor in Chief Irving H. Zucker (University of Nebraska Medical Center) interviews lead author Mark C. Chappell (Wake Forest University) and expert Paul McCray (University of Iowa) about the new Perspective by South et al on “COVID-19, ACE2 and the Cardiovascular Consequences.” We discuss whether the deleterious effects of SARS-CoV-2 are mediated through increasing Ang-II or augmenting the activity of ACE2. In this wide-ranging conversation our experts also discuss the kidney, the small intestine, and the heart—organs which express ACE2 and may be targeted by infection through viremia. We also touch on why the African American community has been disproportionately affected by COVID-19, sex differences, additional co-morbidities, and ACE-inhibitors. Listen now.

 

Andrew M. South, Debra I. Diz, and Mark C. Chappell COVID-19, ACE2, and the cardiovascular consequences Am J Physiol Heart Circ Physiol, published April 13, 2020. DOI: doi.org/10.1152/ajpheart.00217.2020