Metaboreflex-induced Functional Coronary Vasoconstriction

How does the muscle metaboreflex work to regulate coronary blood flow during exercise, particularly in the cardiovascular disease state of hypertension? Listen as Editor in Chief Irving H. Zucker (University of Nebraska Medical Center) interviews lead author Donal O’Leary (Wayne State University School of Medicine) and content expert David Stepp (Augusta University) about the large animal study conducted by O’Leary and colleagues, a technical tour de force which explored whether blocking an increase in vasoconstriction due to increased sympathetic activity in the heart would actually increase coronary blood flow and increase ventricular function. Does this elegant study make the case for focusing on coronary blood flow, rather than blood pressure, as a potential therapeutic target for the treatment of hypertension? Listen to find out.


Marty D. Spranger, Jasdeep Kaur, Javier A. Sala-Mercado, Abhinav C. Krishnan, Rania Abu-Hamdah, Alberto Alvarez, Tiago M. Machado, Robert A. Augustyniak, Donal S. O'Leary Exaggerated coronary vasoconstriction limits muscle metaboreflex-induced increases in ventricular performance in hypertension Am J Physiol Heart Circ Physiol, published online October 21, 2016. DOI: 10.1152/ajpheart.00417.2016


Acute Progesterone Modifies Cardiac Contraction

If cardiovascular scientists use only male animals in animal model studies, will important observations be missed? Yes, according to a new study by Feridooni et al. In this podcast, Editor in Chief Irving H. Zucker interviews lead author Susan Howlett (Dalhousie University, Canada) and content expert Lea Delbridge (University of Melbourne, Australia) about the work by Howlett and colleagues which explored the acute effects of progesterone on the heart. The key finding is that in female mouse hearts—but not in male mouse hearts—progesterone markedly slowed and attenuated contractions in multicellular ventricular muscle, but had no effect on the underlying calcium transients. This surprising data might never have been discovered if Howlett and colleagues had conducted their experiments only on male mice. Does the estrous cycle in female rodents create physiological heterogeneity that is too confounding to experimentally overcome? Does the negative inotropic impact of progesterone shown in vitro translate to the in vivo setting? Listen and learn more.


Hirad A Feridooni, Jennifer K MacDonald, Anjali Ghimire, W. Glen Pyle, Susan E. Howlett Acute exposure to progesterone attenuates cardiac contraction by modifying myofilament calcium sensitivity in the female mouse heart Am J Physiol Heart Circ Physiol, published online October 28, 2016. DOI: 10.1152/ajpheart.00073.2016