AJP-Heart and Circulatory Physiology Podcast

Piezo1 Mechanotransduction in the Uterine Circulation

Is the Piezo1 cation channel the sensor for shear stress that triggers uterine blood vessel growth and vasodilation in pregnancy? Listen as Editor in Chief Irving H. Zucker (University of Nebraska Medical Center) interviews lead author George Osol (University of Vermont College of Medicine) and content expert Kirk Conrad (University of Florida University of Florida College of Medicine) about the new study by John et al that explores the presence of Piezo1 in the uterine circulation, and the channel’s response to shear stress and the link to nitric oxide in both pregnant and non-pregnant uterine arteries. In the context of pregnancy, might a defect in Piezo1 expression or physiology trigger trophoblast invasion and spiral artery remodeling which lead to preeclampsia? Listen and learn more.

 

Liam John, Nga Ling Ko, Alexander Gokin, Natalia Gokina, Maurizio Mandala, and George Osol The Piezo1 Cation Channel Mediates Uterine Artery Shear Stress Mechanotransduction and Vasodilation During Rat Pregnancy Am J Physiol Heart Circ Physiol, published July 13, 2018. DOI: 10.1152/ajpheart.00103.2018

Vascular Smooth Muscle Actin Depolymerization

Is actin depolymerization the mechanism that causes vasodilation in small resistance arterioles? Listen as Associate Editor Robert Hester (University of Mississippi Medical Center) and content expert William Jackson (Michigan State University) interview lead author Philip Clifford (University of Illinois at Chicago) about the new study by Clifford et al. Using two different vasodilators with two different mechanisms of action, Clifford and co-authors found that there was an increase in the G-actin to sm22apha ratio, signaling a reduction in the amount of F-actin in the cell. Both vasodilators investigated-- pinacidil and sodium nitroprusside—act partially through an actin depolymerization. However, sodium nitroprusside is more dependent on this mechanism to achieve vasodilation. What is the time course of this change in actin polymerization? Is depolymerization essential for vasodilation, or a by-product of vasodilation? Listen to our experts and find out.

 

Philip S. Clifford, Brian S. Ferguson, Jeffrey L. Jasperse, and Michael A. Hill Arteriolar vasodilation involves actin depolymerization Am J Physiol Heart Circ Physiol, published August 8, 2018. DOI: 10.1152/ajpheart.00723.2017

Reversal of Microvascular Dysfunction

Can existing vascular disease be reversed? Listen as Associate Editor Robert Hester (University of Mississippi Medical Center) interviews lead author Jefferson Frisbee (University of Western Ontario) and content expert Geraldine Clough (University of Southampton) about the novel new work by Lemaster et al, which utilized a chronically obese animal model to attempt to reverse established vascular dysfunction rather than blunt disease development. After treatment with chronic atorvastatin, or chronic treadmill exercise, or both, Frisbee and colleagues observed improvement in endothelial function, however with some residual vasculopathy. What unique insights were gained by using a multi-scale approach from whole animal to isolated tissues? Do these observations have translational implications for treatment of microvascular dysfunction in patients? Listen and find out.

 

Kent A Lemaster, Stephanie J Frisbee, Luc DuBois, Nikolaos Tzemos, Fan Wu, Matthew T Lewis, Robert W. Wiseman, and Jefferson C. Frisbee Chronic Atorvastatin and Exercise Can Partially Reverse Established Skeletal Muscle Microvasculopathy in Metabolic Syndrome  Am J Physiol Heart Circ Physiol. Published June 22, 2018. DOI: 10.1152/ajpheart.00193.2018

Fibroblast Phenotypic Changes in the Aging Heart

Why is it important to understand resident cardiac fibroblasts and how they change with aging? In this thought-provoking podcast, Deputy Editor Merry Lindsey (University of Mississippi Medical Center) interviews lead author Katarzyna Cieslik (Baylor College of Medicine) and content expert Michael Czubryt (University of Manitoba) about the insightful Review article by Trial and Cieslik. Fibroblasts are no longer considered mere support cells producing matrix protein, explains Cieslik. Rather, fibroblasts have complex physiology and a phenotype altered by aging. Listen as our experts unravel the many faces of fibroblasts, from promoting inflammation to producing extracellular matrix protein. Can observations made in young healthy fibroblasts be extrapolated across ages and pathologies? Listen and find out.

 

JoAnn Trial and Katarzyna A. Cieslik Changes in Cardiac Resident Fibroblast Physiology and Phenotype in Aging Am J Physiol Heart Circ Physiol, published June 15, 2018. DOI: 10.1152/ajpheart.00237.2018

Japanese Language Podcast: Type of Resistance Exercise and Endothelial Function

In this special Japanese-language podcast, we explore an important exercise physiology question: Can high-intensity resistance exercise, combined with low repetitions, maintain endothelial function? Listen as Associate Editor Masafumi Kitakaze (National Cerebral and Cardiovascular Center, Japan) interviews lead author Takuma Morishima (Hosei University, Japan) and content expert Osamu Tsukamoto (Osaka University, Japan) about the novel work by Morishima and co-authors. By studying young, healthy male volunteers, the authors found that both moderate-intensity resistance exercise with moderate repetitions, and low-intensity resistance exercise with high repetitions caused significant impairment in endothelial function. In stark contrast, the authors found that high-intensity resistance exercise with low repetitions prevents endothelial dysfunction. While these findings offer key insights for young, healthy men participating in resistance exercise programs, what are the implications for older adults, women, and hypertension patients? Listen and find out.

 

Takuma Morishima, Yosuke Tsuchiya, Motoyuki Iemitsu, and Eisuke Ochi High-intensity resistance exercise with low repetitions maintains endothelial function Am J Physiol Heart Circ Physiol, published June 1, 2018. DOI: 10.1152/ajpheart.00281.2018

Type of Resistance Exercise and Endothelial Function

Can high-intensity resistance exercise, combined with low repetitions, maintain endothelial function? Listen as Associate Editor Masafumi Kitakaze (National Cerebral and Cardiovascular Center, Japan) interviews lead author Takuma Morishima (Hosei University, Japan) and content expert Osamu Tsukamoto (Osaka University, Japan) about the novel work by Morishima and co-authors. By studying young, healthy male volunteers, the authors found that both moderate-intensity resistance exercise with moderate repetitions, and low-intensity resistance exercise with high repetitions caused significant impairment in endothelial function. In stark contrast, the authors found that high-intensity resistance exercise with low repetitions prevents endothelial dysfunction. While these findings offer key insights for young, healthy men participating in resistance exercise programs, what are the implications for older adults, women, and hypertension patients? Listen and find out.

 

Takuma Morishima, Yosuke Tsuchiya, Motoyuki Iemitsu, and Eisuke Ochi High-intensity resistance exercise with low repetitions maintains endothelial function Am J Physiol Heart Circ Physiol, published June 1, 2018. DOI: 10.1152/ajpheart.00281.2018

Different Roles of ENaC in Carotid and Mesenteric Arteries

Are ENaC (Epithelial Na+ channels) sheer sensors in arteries? This is the central question we explore in our latest podcast, as Associate Editor Robert Hester (University of Mississippi Medical Center) and content expert Heather Drummond (University of Mississippi Medical Center) interview lead author Martin Fronius (University of Otago, New Zealand) about the intriguing new work by Ashley et al. Fronius and co-authors observed a dilation in vessel diameter in carotid arteries when ENaC was blocked. In contrast, blocking ENaC in mesenteric arteries resulted in vasoconstriction. Does the architecture of the ENaC itself, in endothelial cells compared to smooth muscle cells, affect the response to sheer stress? Listen and find out.

 

Zoe Ashley, Sama Mugloo, Fiona J. McDonald, and Martin Fronius Epithelial Na+ channel differentially contributes to shear stress-mediated vascular responsiveness in carotid and mesenteric arteries from mice Am J Physiol Heart Circ Physiol, published May 1, 2018. DOI: 10.1152/ajpheart.00506.2017

Sex, Cycle and Contraceptive Phase on Endothelial Function

Is brachial artery endothelial function in healthy premenopausal women negatively impacted by longer term use of oral contraceptive pills? Listen as Guest Editor Milton H. Hamblin (Tulane University School of Medicine) interviews lead author Maureen MacDonald (McMaster University) and content expert Daniel Credeur (University of Southern Mississippi) about the novel work by Shenouda et al, which was inspired by a lack of information in the scientific literature about controlling for contraceptive pill use and menstrual cycle when assessing endothelial function in healthy humans. There are estimates that over 67 million women worldwide are using oral contraceptive pills, yet the effect of this medication on vascular endothelial and smooth muscle physiology is dramatically understudied. Does brachial artery flow mediated dilation change across the menstrual cycle in healthy women? How do these results compare to men? Listen, read, and find out.

 

Ninette Shenouda, Stacey E. Priest, Vanessa I. Rizzuto, and Maureen J. MacDonald Brachial artery endothelial function is stable across a menstrual and oral contraceptive pill cycle, but lower in premenopausal women than age-matched men Am J Physiol Heart Circ Physiol, published May 4, 2018. DOI: 10.1152/ajpheart.00102.2018

Preclinical Echocardiography: Training and Guidelines

Given the current conversations around rigor and reproducibility, and the need to reinforce scientific research to the public, our latest podcast is particularly timely. Deputy Editor Merry Lindsey (University of Mississippi Medical Center) interviews lead author Daniel Donner (Baker Heart and Diabetes Institute) and content expert Lisandra de Castro Bras (East Carolina University) about the unique study by Donner and colleagues focused on standardizing the quality of echocardiography in mice at Baker Heart and Diabetes Institute, Melbourne, Australia. Listen as we address the importance of consistent training for echocardiography readers on the analysis of echocardiographic images. Did Donner and co-authors find that implementing a short, formal preclinical echo training program at Baker Heart and Diabetes was as onerous as they originally anticipated? Power analysis in the study by Donner et al revealed that sample sizes needed to detect differences were reduced more than 50% after training. What are the implications of reductions in sample size on improving methodology, reducing animal numbers, and reducing research costs? Listen now.

 

Daniel G. Donner, Helen Kiriazis, Xiao-Jun Du, Thomas H. Marwick, and Julie R. McMullen Improving the quality of preclinical research echocardiography: Observations, training and guidelines for measurement Am J Physiol Heart Circ Physiol, published online April 20, 2018 DOI: 10.1152/ajpheart.00157.2018

MicroRNA Translocation into the Mitochondria

In this podcast, we explore the exciting field of mitochondrial transcriptomics. Guest Editor John Hollander (West Virginia University School of Medicine) interviews lead author Samarjit Das (Johns Hopkins University) and content expert Paras Mishra (University of Nebraska Medical Center) about the new Review by Anne Macgregor-Das and Samarjit Das which expands our understanding of the intersection between mitochondria and non-coding RNAs. The mitochondrial genome only contains 13 protein encoding genes. Questions abound: Why are so many microRNAs found in the mitochondria, and do they all bind to mitochondrial mRNAs? What percentage of mitomereres are directly involved in the regulation of the mitochondrial genome? What diseases do our experts envision benefitting from microRNA therapeutics in the near future? Listen to find the answers.

 

Anne M. Macgregor-Das and Samarjit Das A microRNA's Journey to the Center of the Mitochondria Am J Physiol Heart Circ Physiol, published March 23, 2018. DOI: 10.1152/ajpheart.00452.2017