Can hormonal fluctuations across a single menstrual cycle alter arterial wave reflections and wasted pressure effort? In this episode, Associate Editor Dr. Jonathan Kirk (Loyola University Chicago) interviews author Dr. Ninette Shenouda (University of Delaware) and expert Dr. Sarah Baker (Mayo Clinic) about the latest study by Shenouda et al. investigating sex differences and ventricular arterial interactions. The authors wanted to understand how strategic phases of the menstrual cycle might affect the relationship between the left ventricle (LV) and the arterial system, as this relationship is crucial for maintaining adequate cardiac output and blood pressure. Given the established beneficial effects of estradiol on the vasculature, the authors hypothesized that their cohort of naturally menstruating premenopausal women would have favorable reductions in total peripheral resistance and favorable changes in the arterial wave reflection profile during the high hormone cycle phases, compared to age matched men. What were the unexpected findings? Listen now to find out.   Ninette Shenouda, Joseph M. Stock, Nicholas V. Chouramanis, Zoe R. Lincoln, Megan M. Wenner, Julio A. Chirinos, and David G. Edwards Favorable alterations in ventricular-arterial interactions across the menstrual cycle in healthy premenopausal women Am J Physiol Heart Circ Physiol, published February 28, 2025. DOI: 10.1152/ajpheart.00363.2024

In this episode, Deputy Editor Dr. Zamaneh Kassiri (University of Alberta) interviews authors Dr. Oliver H. Wearing (University of British Columbia), Dr. Naomi C. Chesler (University of California Irvine), Dr. Mitchel J. Colebank (University of South Carolina), Dr. Timothy A. Hacker (University of Wisconsin-Madison), Dr. John N. Lorenz (University of Cincinnati), and Dr. Christopher R. West (University of British Columbia) about their new Guidelines in Cardiovascular Research article. This must-read Guidelines article provides a thorough overview of ventricular pressure-volume (PV) measurements in the mouse heart. PV measurements are an invasive method for assessment of heart function, and if done correctly, can provide researchers with valuable information about heart hemodynamics and the relationship between changes in ventricular pressure and volume during a cardiac cycle. The authors discuss PV measurements as the gold standard for assessing cardiac in vivo function. How do PV measurements differ from, and provide a complement to, echocardiography measurements? Listen and find out more.   Oliver H. Wearing, Naomi C. Chesler, Mitchel J. Colebank, Timothy A. Hacker, John N. Lorenz, Jeremy A. Simpson, and Christopher R. West Guidelines for assessing ventricular pressure-volume relationships in rodents Am J Physiol Heart Circ Physiol, published January 2, 2025. DOI: 10.1152/ajpheart.00434.2024

In our latest episode, Dr. Jeff Saucerman (University of Virginia) interviews authors Dr. Naomi Chesler (University of California, Irvine) and Dr. Mitchel Colebank (University of South Carolina) about their new Guidelines in Cardiovascular Research article on incorporating mechanistic modeling into the analysis of experimental and clinical data to identify possible mechanisms of (ab)normal cardiovascular physiology. The authors’ goal is to provide a consensus document that identifies best practices for in silico computational modeling in cardiovascular research. These guidelines provide the necessary methods for mechanistic model development, model analysis, and formal model calibration using fundamentals from statistics. Colebank et al. outline rigorous practices for computational, mechanistic modeling in cardiovascular research and discuss its synergistic value to experimental and clinical data. Would you like to understand how to apply a cone of uncertainty to your experimental data? Listen now to find out more.   Mitchel J. Colebank, Pim A. Oomen, Colleen M. Witzenburg, Anna Grosberg, Daniel A. Beard, Dirk Husmeier, Mette S. Olufsen, and Naomi C. Chesler Guidelines for mechanistic modeling and analysis in cardiovascular research Am J Physiol Heart Circ Physiol, published August 6, 2024. DOI: 10.1152/ajpheart.00253.2024

In this episode of Behind the Bench, we are talking with Hannah Cizauskas about her first, first-author article published in AJP-Heart and Circ. Born and raised in Detroit, Hannah moved to Chicago for what she thought would be just one rotation outside of the cancer genetics field. This led Hannah to work on a project related to atrial fibrillation and contractile dysfunction in Dave Barefield’s lab at Loyola University Chicago’s Cellular and Molecular Physiology Department. Now in the fourth year of her PhD, Hannah is a dog mom to Jake, she loves reading STEMinist novels, and she is researching sarcomere dysfunction in the context of AFib. Listen to this engaging interview with co-hosts Dr. Tommy Martin and Dr. Charlotte Usselman to find out more.   Hannah E. Cizauskas, Hope V. Burnham, Azaria Panni, Alexandra Peña, Alejandro Alvarez-Arce, M. Therese Davis, Kelly N. Araujo, Christine E. Delligatti, Eby Edassery, Jonathan A. Kirk, Rishi Arora, and David Y. Barefield Proteolytic degradation of atrial sarcomere proteins underlies contractile defects in atrial fibrillation Am J Physiol Heart Circ Physiol, published August 5, 2024. DOI: 10.1152/ajpheart.00148.2024

In our latest episode, Executive Editor Kara Hansell Keehan interviews lead author Dr. Michaela Patterson and first author Kaelin Akins (both at the Medical College of Wisconsin) along with expert Dr. Ana Vujic (University of Cambridge) about the new study by Akins et al. Given that the heart has limited regenerative potential, repairing damage to cardiomyocytes after a heart attack is particularly challenging. Cardioregeneration researchers worldwide are searching for potential targets that can stimulate cardiomyocyte proliferation and cardiac regeneration. However, because cardiomyocytes can undergo incomplete cell division, multinucleation, and polyploidization, it is difficult to study true cardiomyocyte proliferation. Akins et al. examined the effect of Runx1 on cardiomyocyte cell cycle during postnatal development and cardiac regeneration using cardiomyocyte-specific gain- and loss-of-function mouse models. Listen now to learn more about how the authors determined that Runx1 is sufficient but not required for cardiomyocyte cell cycle activation.   Kaelin A. Akins, Michael A. Flinn, Samantha K. Swift, Smrithi V. Chanjeevaram, Alexandra L. Purdy, Tyler Buddell, Mary E. Kolell, Kaitlyn G. Andresen, Samantha Paddock, Sydney L. Buday, Matthew B. Veldman, Caitlin C. O’Meara, Michaela Patterson Runx1 is sufficient but not required for cardiomyocyte cell-cycle activation Am J Physiol Heart Circ Physiol, published July 21, 2024. DOI: 10.1152/ajpheart.00782.2023

What is the impact of central insulin on muscle sympathetic nerve activity (MSNA) and vascular conductance in the absence of peripheral insulin delivery? Listen as Associate Editor Dr. Jason Carter (Baylor University) interviews authors Neil McMillan and Dr. Jackie Limberg (both at University of Missouri), along with expert Dr. Manda Keller-Ross (University of Minnesota), about the new Short Report by McMillan et al. To gain a better understanding of the central sympathoexcitatory effects of insulin in humans, the authors recruited two groups of young, healthy individuals. One group served as a time control and the other group received intranasal insulin administration. McMillan et al. measured MSNA from the fibular nerve, combined with continuous monitoring of blood pressure and leg blood flow, before and after insulin administration. Limberg, McMillan and co-authors found that only the individuals who received insulin exhibited an increase in efferent sympathetic nervous system activity, which was coupled with peripheral vasoconstriction and increases in arterial blood pressure. How does this research influence our mechanistic understanding of the sympathetic and hemodynamic response to insulin? Listen now to find out.   Neil J. McMillan, Dain W. Jacob, Brian Shariffi, Jennifer L. Harper, Glen E. Foster, Camila Manrique-Acevedo, Jaume Padilla, and Jacqueline K. Limberg Effect of acute intranasal insulin administration on muscle sympathetic nerve activity in healthy young adults Am J Physiol Heart Circ Physiol, published July 3, 2024. DOI: 10.1152/ajpheart.00253.2024

Sometimes experimental results are serendipitous. Listen as Associate Editor Dr. Crystal Ripplinger (University of California, Davis) talks with authors Dr. Nikki Posnack and Devon Guerrelli (both at Children’s National Hospital and The George Washington University School of Engineering and Applied Science), along with expert Dr. Silvia Marchiano (University of Washington), about the new research by Guerrelli et al. published in our Call for Papers on Excitation-Contraction Coupling, Electrophysiology, and Arrhythmias. The Posnack Lab typically investigates environmental chemicals and their impact on cardiac function using microelectrode arrays to record electrical signals from human iPS cells. When performing cardiotoxicity experiments, the authors realized that their baseline measurements varied significantly between their different studies, making it difficult to combine datasets. In doing the legwork to identify potential sources of variability and improve their own internal lab protocols, the authors focused on the reproducibility of their experimental measurements using human iPSCs. Listen as we discuss important recommendations for investigators using these cells to improve their experimental reproducibility.   Devon Guerrelli, Jenna Pressman, Shatha Salameh, and Nikki Posnack hiPSC-CM Electrophysiology: Impact of Temporal Changes and Study Parameters on Experimental Reproducibility Am J Physiol Heart Circ Physiol, published June 9, 2024. DOI: 10.1152/ajpheart.00631.2023

Hormone modulation therapy is a growing area of research in cardiovascular science related to a number of factors, such as menopause and andropause, cancers in hormone-producing organs, as well as gender-affirming hormone therapy. So how do scientists and clinicians measure, monitor, and balance applications of hormone therapy? In our latest podcast, Associate Dr. Keith Brunt interviews authors Dr. Chantal Rytz (University of Calgary) and Dr. Sofia Ahmed (University of Alberta), along with expert Dr. Nina Stachenfeld (John B. Pierce Laboratory/Yale School of Medicine) about the recent article by Rytz et al. The authors review the use of estrogen in adult transgender, non-binary and gender diverse individuals who are medically managed with hormone modulation therapy for gender affirmation. Their findings indicate that the rate at which serum estrogen concentrations change may be important in order to optimize cardiovascular health and manage risk factors for obesity, hyperlipidemia, and elevated blood pressure. How should scientists account for and explore the hormone state of individuals within a cardiovascular context to improve the foundation of evidence for hormone modulation therapies for clinicians? Listen and learn more.   Chantal L. Rytz, Keila Turino Miranda, Paul E. Ronksley, Nathalie Saad, Satish R. Raj, Ranjani Somayaji, Sandra M. Dumanski, Heather Ganshorn, Dina N. Greene, David Collister, Amelia M. Newbert, Lindsay Peace, Sofia B. Ahmed Association between Serum Estradiol and Cardiovascular Health among Transgender Adults Using Gender-Affirming Estrogen Therapy Am J Physiol Heart Circ Physiol, published July 15, 2024. DOI: 10.1152/ajpheart.00151.2024

While decreased IL-33 signaling has been associated with preeclampsia, the mechanisms linking this signaling pathway to disease pathophysiology are not well understood. In this episode, Associate Editor Dr. Amanda LeBlanc (University of Louisville) interviews author Dr. Denise Cornelius (University of Mississippi Medical Center) and expert Dr. Stella Goulopoulou (Loma Linda University) about the new research study by Wang et al. Using the Reduced Uterine Perfusion Pressure (RUPP) rat model, the authors found evidence that mechanistically links reduced IL-33 with the inflammatory response and vascular dysfunction present in preeclampsia. Is the IL-33 signaling pathway a possible clinical therapeutic target for the treatment of preeclampsia? Listen now to learn more.   Xi Wang, Corbin Shields, Geilda Tardo, Greg Peacock, Emily Hester, Marissa Anderson, Jan M. Williams, Denise C. Cornelius IL-33 supplementation improves uterine artery resistance and maternal hypertension in response to placental ischemia Am J Physiol Heart Circ Physiol, published April 3, 2024. DOI: 10.1152/ajpheart.00045.2024

In this episode, Associate Editor Dr. Jonathan Kirk (Loyola University Chicago) interviews author Dr. Ed Lesnefsky (Richmond Department of Veterans Affairs Medical Center and Virginia Commonwealth University) and expert Dr. Chi Fung Lee (Oklahoma Medical Research Foundation) about the new Methods and Resources article by Chen et al. published in our Call for Papers on Impact of Aging on the Cardiovascular System. Lesnefsky and coauthors advanced a technique of isolating mitochondria with an emphasis on integrity of the mitochondrial organelles, their function, purity and characterization in order to develop benchmarks in the field for quality control to support collaboration across laboratories. In their research, the authors focus on mitochondrial-driven age-enhanced disease and on mitochondrial defects due to aging, which potentially increase the susceptibility of elderly patients’ hearts to cardiovascular disease. Well-known techniques exist for isolating specific mitochondria populations in mouse hearts. However, Lesnefsky and collaborators found that this resulted in not enough sample to properly interrogate. Therefore Lesnefsky and coauthors investigated whether they could isolate one combined mixed population of mitochondria with a “wild type” physiological model of aging, and whether or not that would that reflect the phenotype. Listen as we discuss the importance of studying mitochondria in an aging model as well as the strategy Lesnefsky and colleagues used to develop their protocol for isolating a mixed mitochondria population. Don’t miss the last few minutes of this conversation for pro tips about the value of networking and career-long mentors. Listen now.   Qun Chen, Jeremy Thompson, Ying Hu, and Edward J. Lesnefsky Aging-induced mitochondrial dysfunction: two distinct populations of mitochondria versus a combined population Am J Physiol Heart Circ Physiol, published January 12, 2024. DOI: 10.1152/ajpheart.00363.2023

In our latest episode, Consulting Editor Dr. Kristine DeLeon-Pennell (Medical University of South Carolina) interviews fellow co-authors Dr. Charlotte Usselman (McGill University), Dr. Judy Regensteiner (University of Colorado Anschutz Medical Campus), Dr. Kerrie Moreau (University of Colorado Anschutz Medical Campus), Dr. Austin Robinson (Indiana University Bloomington), Dr. Jesse Moreira-Bouchard (Boston University), and Dr. Quin Denfeld (Oregon Health and Science University) about their recently published guidelines on the use of sex and gender in cardiovascular research. Until recently, the effects of sex and gender in cardiovascular research have been largely ignored in research design and reporting. The result is that women and gender diverse individuals have been understudied in basic and clinical research, leading to a lack of understanding of sex and gender in cardiovascular health and disease. The goal of these guidelines is to provide researchers with practical and actionable advice on best practices to include sex and gender considerations in study design, data collection, analysis, and interpretation. As Dr. Judy Regensteiner points out, “We have to make it doable. We can’t just say, ‘Go do this.’ We have to show people how to do it.” Ready to get started? Listen now to learn more.   Charlotte W. Usselman, Merry L. Lindsey, Austin T. Robinson, Beth A. Habecker, Chloe E. Taylor, W. David Merryman, Derek Kimmerly, Jeffrey R. Bender, Judith G. Regensteiner, Kerrie L. Moreau, Louise Pilote, Megan M. Wenner, Myles O’Brien, Timur O. Yarovinsky, Nina S. Stachenfeld, Nisha Charkoudian, Quin E. Denfeld, Jesse D. Moreira-Bouchard, W. Glen Pyle, and Kristine Y. DeLeon-Pennell Guidelines on the use of sex and gender in cardiovascular research Am J Physiol Heart Circ Physiol, published December 21, 2023. DOI: 10.1152/ajpheart.00535.2023

After a yearlong hiatus, Behind the Bench is back, listeners! In this episode, we welcome back our B2B co-hosts Dr. Charlotte Usselman and Dr. Tommy Martin, who get the story behind the story from the one and only Dr. DeWayne Townsend, corresponding author of the recently published study by Stevens et al. Trust me, you are going to love listening to DeWayne talk about science! As DeWayne rightly points out, if we want to understand a disease before it's a disease, we have to model it in order to figure it out. From the “dastardly Krebs cycle” to grinding up hearts and shouting “fire in the hole!” before using the mouse heart pulverizer (it’s a thing), Dewayne brings to this conversation his best science sound effects, wise insights, and a friendly PSA to contact your Congressional representatives and advocate for science funding. We discuss the resiliency of physiology and the redundancies in the heart that enable scientists to knockout things thought to be important, and as DeWayne points out, the body can still handle it. We cover DeWayne’s interesting path from vet school to cardiovascular physiology, and his best advice to trainees. How do you deal with being wrong most of the time? According to DeWayne, when another beautiful hypothesis is slain by data, push on! It is a slog. Keep going and try to find a way to move the needle. While you’re at it, DeWayne suggests that you learn how to fix your own equipment, try not to drink too much caffeine, and be inspired by other scientists, especially when that scientist is your Dad.   Jackie A. Stevens, Tyler C. Dobratz, Kaleb D. Fischer, Alexandria Palmer, Kira Bourdage, Anne J. Wong, Hector Chapoy-Villanueva, Daniel J. Garry, Julia C. Liu, Matthew W. Kay, Sarah Kuzmiak-Glancy, and DeWayne Townsend Mechanisms of reduced myocardial energetics of the dystrophic heart Am J Physiol Heart Circ Physiol, published January 22, 2024. DOI: 10.1152/ajpheart.00636.2023

In our latest episode, Associate Editor Dr. Amanda LeBlanc (University of Louisville) interviews author Prof. Pietro Modesti (University of Florence) and expert Dr. Alexandre da Silva (University of Mississippi Medical Center) about the new study by Pellegrino et al. that investigated the pattern of intraventricular hemodynamic forces associated with left ventricular function in women with uncomplicated twin pregnancy. The authors found that, in twin pregnancy, hemodynamic forces misalignment in the first trimester precedes a slight temporary decrease in left ventricular systolic function in the second trimester. In the third trimester, a rightward shift of the end diastolic pressure relationship (EDPR) was, in fact, associated with a realignment of hemodynamic forces and normalization of ventricular contractility indices. Why is twin pregnancy an ideal physiological condition to study increased ventricular workload over time? Listen to this insightful conversation and find out.   Alessio Pellegrino, Loira Toncelli, Lucia Pasquini, Giulia Masini, Federico Mecacci, Gianni Pedrizzetti, and Pietro Amedeo Modesti Left ventricular remodeling in twin pregnancy, noninvasively assessed using hemodynamic forces and pressure-volume relation analysis: prospective, cohort study Am J Physiol Heart Circ Physiol, published January 23, 2024. DOI: 10.1152/ajpheart.00699.2023

Ready Player One? In our latest episode, Dr. Keith Brunt (Dalhousie University) interviews lead author Dr. Joanne DiFrancisco-Donoghue (New York Institute of Technology) and expert Dr. Saurabh Thosar (Oregon Health and Science University Hospital) about a new article published in the AJP-Heart and Circ Call for Papers on Exercise, Physical Activity, and Cardiovascular Health. DiFrancisco-Donoghue et al. raise an important question about the risk for college level e-sport athletes, professionals, and recreational gamers to develop deep vein thromboses. Using Doppler ultrasound recordings of blood flow velocity and volume, the authors found a decrease in both measures when e-sport play was interrupted with a 6-minute walk. DiFrancisco-Donoghue and co-authors found a similar decrease when e-sport athletes wore compression sleeves during play. Could either a break in play for a brief walk or wearing compression stockings help e-sport athletes avoid the risk of deep vein thrombosis caused by prolonged sitting? What effects might this have on executive function, improvement in game play, and for that matter, sleep? If you are a recreational gamer or hoping to go professional, a casual e-sports spectator, or even an active member of the military sitting for prolonged periods of time, you don’t want to miss this engaging and enlightening episode! Listen now.   Joanne DiFrancisco-Donoghue, Kelly Borges, Timothy Li, Olivia Ballone, Hallie Zwibel, and Peter C. Douris Reducing thrombotic risks in video gamers: investigating the benefits of walking and compression sleeves on blood hemodynamics Am J Physiol Heart Circ Physiol, published February 8, 2024. DOI: 10.1152/ajpheart.00669.2023     I Spy Physiology Blog by Erica RothHow Can Walking and Wearing Socks Help Video Gamers?

What is the relationship between cardiovascular developmental programming and the risk of stroke later in life? Listen as Guest Editor Dr. Helen E. Collins (University of Louisville) interviews author Dr. Nafisa Jadavji (Midwestern University) and expert Dr. Deanne Hryciw (Griffith University) about the latest research by Pull et al. looking at underlying mechanisms associated with a poor-quality diet during pregnancy. One-carbon metabolism is essential for biosynthesis of DNA and proteins, as well as methylation. Jadavji and co-authors demonstrated that maternal dietary deficiency in one-carbon (1C) metabolism, either in folic acid or choline, resulted in reduced cerebral blood flow in adult offspring after an ischemic stroke. Pull et al. focused their investigation on female offspring and identified this effect in 3-month-old offspring but not 11-month-old offspring. The results point to the key role that maternal diet has in early life programming, fetal development, and long-term cerebrovascular health. Are there many downstream pathways that are altered by one-carbon metabolism deficiencies? Is there a negative impact of folic acid over-supplementation? Listen now to find out.   Kasey Pull, Robert Folk, Jeemin Kang, Shaley Jackson, Brikena Gusek, Mitra Esfandiarei, and Nafisa M. Jadavji Impact of maternal dietary folic acid or choline dietary deficiencies on vascular function in young and middle-aged female mouse offspring after ischemic stroke   Am J Physiol Heart Circ Physiol, published October 30, 2023. DOI: 10.1152/ajpheart.00502.2023

Given that there appears to be variation in significant risk to the cardiovascular system following SARS-CoV2 infection with regard to age and sex, the latest study by Rouhana et al. provides a foundation for studying sex differences with a preclinical model of infection to the direct exposure to SARS-CoV-2 and the impact on the myocardium of ferrets. Listen as Associate Editor Dr. Keith Brunt (Dalhousie University) interviews authors Dr. Alyson Kelvin (University of Saskatchewan) and Dr. Glen Pyle (University of Guelph) along with expert Dr. Susan Cheng (Cedars-Sinai Smidt Heart Institute). The authors identified that phosphokinase expression, normally associated with cardiac stress remodeling, is distinct by time and sex effects. Additionally, the authors found that inflammatory patterns of macrophage markers showed inherent sex differences in immune responses at the level of the myocardium. Why are ferrets a such a useful preclinical model for understanding SARS-CoV2 infection? How do immune inflammatory responses differ by sex, timing, and age? As Dr. Brunt points out, “There is power in observation, collaboration, and when it comes to bugs and bodies…it’s physiology.” Read the paper, listen to this podcast, and find out more.   Sarah Rouhana, Kathy Jacyniak, Magen E. Francis, Darryl Falzarano, Alyson A. Kelvin, W. Glen Pyle Sex differences in the cardiac stress response following SARS-CoV-2 infection of ferrets Am J Physiol Heart Circ Physiol, published October 18, 2023. DOI: 10.1152/ajpheart.00101.2023

What does a mouse heart have to do with an M&M candy (the regular kind, not the peanut variety)? In our latest episode, Associate Editor Dr. Crystal Ripplinger (University of California, Davis) interviews author Dr. Tim Domeier (University of Missouri) and expert Dr. DeWayne Townsend (University of Minnesota) about the recent study by Haffner et al et al. The authors examined cardiac calcium mishandling and damage in the setting of Duchenne muscular dystrophy (DMD). Using a genetic mouse model of DMD crossed with a mouse that expresses a genetically encoded calcium indicator, Domeier and colleagues investigated changes in intracellular calcium handling in response to increased preload. The unexpected finding was that after the acute preload challenge, many of the cells were missing-in-action. What was going on with these missing cells? Listen as we talk about how individual dystrophic cells blow up if stretched too far, and why pointing microscopes in different directions might be the next step to overcome optical imaging challenges. Don’t miss this episode – the enthusiasm for science, tiny pumping mouse hearts, and squishy cells is contagious!   Vivian Haffner, Zahra Nourian, Erika M. Boerman, Michelle D. Lambert, Laurin M. Hanft, Maike Krenz, Christopher P. Baines, Dongsheng Duan, Kerry S. McDonald, Timothy L. Domeier Calcium handling dysfunction and cardiac damage following acute ventricular preload challenge in the dystrophin-deficient mouse heart Am J Physiol Heart Circ Physiol, published October 18, 2023. DOI: 10.1152/ajpheart.00265.2023

People living with HIV have an increased risk of developing cardiovascular disease, including coronary artery disease. Until now, it has been unclear why. In this episode, Guest Editor Dr. Ashley Walker (University of Oregon) interviews author Dr. Efthymios Ziogos (Johns Hopkins Medicine) and expert Dr. Jennifer Williams (McMaster University) about the recent study by Ziogos et al. published in the Call for Papers Impact of Aging on CV System. Ziogos and co-authors used advanced MRI to assess coronary endothelial function noninvasively and without contrast in order to compare endothelial-dependent vasoreactive responses in coronary arteries to isometric handgrip exercise, both in people living with HIV and HIV negative individuals. The authors found that coronary endothelial function was impaired in people living with HIV, compared to HIV negative individuals. While it is known that there is a negative correlation between age and coronary endothelial function in HIV negative individuals, the authors found no correlation between age and endothelial function in HIV positive individuals, suggesting early vascular aging in individuals with HIV. This study is truly an example of an important research question that went unaddressed until recently because of the need for the advanced measurement techniques used by Ziogos and collaborators. While there is still much to learn about HIV, this research offers new insights into the potential causes of increased coronary artery disease in people living with HIV, and provides new avenues for preventive cardiology research in this population. Listen now to find out more.   Efthymios Ziogos, Yaa A. Kwapong, Robert G. Weiss, Michael Schär, Todd T. Brown, Shashwatee Bagchi, Alborz Soleimanifard, Tarek Harb, Damani A. Piggott, Gary Gerstenblith, Thorsten M. Leucker, Allison G. Hays   Coronary Artery Endothelial Function and Aging in People with HIV and HIV-Negative Individuals   Am J Physiol Heart Circ Physiol, published October 9, 2023. DOI: 10.1152/ajpheart.00143.2023

What does it sound like when a young researcher meets one of his science heroes for the first time? Listen to this episode of The AJP-Heart and Circ Podcast to find out. Associate Editor Dr. Keith Brunt (Dalhousie University) interviews author Dr. Holger Burchert (University of Basel) and leading expert Dr. William Stringer (Lundquist Institute at Harbor-UCLA Medical Center) about a new Methods and Resources article published by Burchert and Klimpel as part of the recent Call for Papers on Exercise, Physical Activity, and Cardiovascular Health. The article by Burchert et al. is an important contribution of methodological advancement built upon a foundation of established literature, dating back to Fick’s Principle, which first appeared as a two-paragraph conference abstract published in German in 1870 and later translated by The New England Journal of Medicine in 1948. Fick was the first to realize that cardiac output is equal to oxygen consumption divided by the arterial mixed venous oxygen content difference, allowing the first accurate determination of cardiac output. While non-invasive measurements of oxygen consumption and heart rate are now routine, sampling arterial and mixed venous blood is inherently challenging. This makes finding non-invasive techniques for these measurements incredibly important. Enter the OG of the linear method for determining the arterial mixed venous oxygen content difference, Dr. William Stringer. In his seminal 1997 article published in the Journal of Applied Physiology, “Cardiac output estimated noninvasively from oxygen uptake during exercise”, Dr. Stringer found that the arterial mixed venous oxygen content difference during incremental exercise can be estimated because it behaves in a predictable, linear fashion, thus avoiding the difficult blood sampling. Reading the article by Stringer et al., which was referenced in the CPET (cardiopulmonary exercise testing) machine manual Burchert used during his PhD work, sparked Burchert’s interest to investigate the literature and ultimately build on Stringer’s methodological approach by collaborating with this former school friend Dr. Fabian Klimpel. Burchert et al. found that a 3rd order polynomial S-curve described the arterial mixed venous oxygen content difference slightly better. More importantly, the authors also determined that the inflection point of this function could be related to the first ventilatory threshold and the inflection point of the oxygen dissociation curve. Why is this important? A deeper understanding of the mechanisms behind the s-shaped response has potential clinical translation, as the method could be further developed by tailoring it to individual patients. Listen as we discuss why it is important for early career researchers “to look back in order to look forward,” to use collaborators from other disciplines to support thinking creatively about cardiovascular physiology, and to align with mentors who facilitate young careers through constructive peer review and publication.   Holger Burchert and Fabian Klimpel Revisiting cardiac output estimated noninvasively from oxygen uptake during exercise: an exploratory hypothesis-generating replication study Am J Physiol Heart Circ Physiol, published August 25, 2023. DOI: 10.1152/ajpheart.00330.2023   William W. Stringer, James E. Hansen, and K. Wasserman Cardiac output estimated noninvasively from oxygen uptake during exercise J Appl Physiol, published March 1, 1997. DOI: 10.1152/jappl.1997.82.3.908   Fick, A On the Measurement of the Blood Quantum in the Ventricles of the Heart. Bauhaus-Universität Weimar, 1870, p. 16.

Come for the yoga metaphors, stay for the science. In this episode, Associate Editor Dr. Keith Brunt (Dalhousie University) interviews author Dr. Stacy Hunter (Texas State University) and expert Dr. Annet Kirabo (Vanderbilt University) about the new study by Hunter et al., which examined the impact of hot yoga on sodium-induced pressor responses and endothelial function of Black women. In a randomized control trial that combined the thermal stress of hot yoga and a salt challenge, the authors investigated human homeostatic regulation in terms of whole-body physiology, cardiorenal responses, physical activity, and the exercise environment. In their study, Hunter and collaborators controlled for sodium intake by separating participants into high and low sodium groups, with pre and post analyses of body mass, ambulatory blood pressure, urinalysis, and flow mediated dilation. The authors found that participants who actively engaged in hot yoga showed increased flow mediated dilation but not increased blood pressure. Why did the authors use a 3-day, not 5-day, hot yoga exercise protocol? What insights can be gained about salt-sensitivity in Black women from this study, which incorporated a form of exercise that activated both thermoregulation and the parasympathetic nervous system? Listen to find out. Stacy D. Hunter, Stavros A. Kavouras, and Mitra Rahimi Exploring heated exercise as a means of preventing the deleterious effects of high-sodium intake in Black women Am J Physiol Heart Circ Physiol, published May 4, 2023. DOI: 10.1152/ajpheart.00699.2022