Archive for August 2015

Is interstitial fibrosis a contributor, among other factors, in the prognosis for patients at high risk for arrhythmias? Yes, according to a new study by Nguyen et al. In this podcast Deputy Editor Merry Lindsey (University of Mississippi Medical Center) interviews lead author Xiao-Jun Du (Baker IDI Heart and Diabetes Institute) about his lab’s latest work exploring the interplay between ventricular arrhythmias, cardiac fibrosis, and the resulting functional consequences. Using a transgenic mouse model of spontaneous ventricular tachyarrhythmias and employing detailed telemetry data analysis, Du and colleagues connected the increase in collagen content and collagen cross-linking with an increase over time in arrhythmia episodes. Is connexin 43 upregulated via cardiomyocytes or fibroblasts? Do interventions using antioxidative stress, such as treating with relaxin, reduce fibrosis and therefore reduce the incidents of arrhythmias? Listen to find out.

My-Nhan Nguyen, Helen Kiriazis, Diego Ruggiero, Xiao-Ming Gao, Yidan Su, Anne Jian, Li-Ping Han, Julie R McMullen, Xiao-Jun Du Spontaneous ventricular tachyarrhythmias in β2-adrenoceptor transgenic mice in relation to cardiac interstitial fibrosis Am J Physiol Heart Circ Physiol, published online June 26, 2015, DOI: 10.1152/ajpheart.00405.2015.

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Exercise guidelines exist for the management and treatment of patients with most cardiovascular diseases, but where does pulmonary arterial hypertension fit into the exercise training therapy picture? In this podcast Guest Editor Shawn Bender interviews lead author Ed White (University of Leeds) and content expert Daphne Merkus (Erasmus MC, Netherlands) about the work by Natali and co-authors, which used an innovative rat model of voluntary wheel running to determine whether exercise training could be beneficial in the treatment of pulmonary artery hypertension (PAH) and right ventricular failure. The authors found that, while wheel running did not prevent the development of PAH, it did significantly delay the median time to heart failure. Will the work by White and collaborators lead to new “off the shelf” exercise training treatments, which could be utilized by clinicians in the treatment of human patients with PAH? Listen and find out.

Antonio José Natali, Ewan Douglas Fowler, Sarah Calaghan, Ed White Voluntary exercise delays heart failure onset in rats with pulmonary artery hypertension Am J Physiol Heart Circ Physiol, published August 1, 2015, DOI: 10.1152/ajpheart.00262.2015.

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If core temperature is not the primary determinant of heat stroke severity, what is? In this latest podcast, Guest Editor Michael Falvo (VA NJ Health Care System; Rutgers New Jersey Medical School) interviews authors Gerald Audet and Nisha Charkoudian (both of US Army Research Institute of Environmental Medicine), along with content expert Robert Matthew Brothers (University of Texas at Austin), about the innovative work by Quinn et al centered on a unique rat model seeking to identify the failures of the cardiovascular system after heat stroke, rather than during heat stroke. What role do reactive oxygen species and the systemic inflammatory cascade play in governing heart rate and arterial pressure responses observed by the authors? How does this experimental model translate to patient populations, such as the elderly or workers doing physical labor, whose cardiovascular reserves are already taxed when heat stress or heat stroke occurs? Listen and learn.

Carrie M. Quinn, Gerald N. Audet, Nisha Charkoudian, Lisa R. Leon Cardiovascular and thermoregulatory dysregulation over 24 h following acute heat stress in rats Am J Physiol Heart Circ Physiol, published August 15, 2015, DOI: 10.1152/ajpheart.00918.2014.

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