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Cardiovascular Center

David Harder Lab

David R. Harder, PhD

David R. Harder, PhD

Kohler Co. Professor in Cardiovascular Research and Associate Dean for Research
Professor, Department of Physiology
dharder@mcw.edu

The major focus of our laboratory is to understand mechanisms regulating the cerebral circulation under physiologic and pathophysiologic conditions. Studies in the laboratory are focused around the astrocyte as both a homeostatic sensor and an active regulator that can affect and protect both the cerebral vasculature and neurons. Our research involves identification and characterization of different ion channel types and second messenger systems in glial cells, neurons, cerebral vascular smooth muscle cells, and endothelial cells. Our goal is to increase our knowledge concerning interactions between lipid mediators and ion channels, second messengers, free radicals, and different enzymatic pathways that mediate both physiologic CNS processes and the pathologic changes in cerebral blood flow and in neural cells.

Debebe Gebremedhin, PhD

Debebe Gebremedhin, PhD

Associate Professor, Physiology
dgebreme@mcw.edu

Our research interests focus in part on investigating the influence of pathophysiological states such as ischemia reperfusion, insulin-dependent diabetes mellitus and Alzheimer's disease on cerebrovascular function. The research areas include physiology of adenosine receptors; patch clamp electrophysiological screening of functions of different ion channel current types including L-type Ca2+ channels, different types of K+ channels, chloride channels, and a variety of TRP channel currents in isolated cerebral vascular smooth muscle cells, endothelial cells, neurons and astrocytes. We also conduct biochemical assay of CYP-derived lipid metabolites, reactive oxygen species, protein kinases and protein phosphatases to elucidate their functional role in different brain cell types.

Kevin Rarick

Kevin R. Rarick, PhD

Research Scientist I
krarick@mcw.edu

My education and research background is in exercise and cardiovascular physiology on a systems level, including human endocrine system responses to physical stressors. Since joining David Harder’s lab in 2012, I have been fortunate to be able to merge integrative approaches using whole animal models and cellular and molecular techniques with the goal of increasing our fundamental understanding of the complex physiologic processes that occur between the cells of the brain and the vascular system. My research interests include how the cellular components of the neurovascular unit communicate to maintain adequate cerebral blood flow, uncoupling of the neurovascular unit in response to hyperglycemia or oxidative stress, and how alterations in blood flow hemodynamics impact the structure and function of cerebral vessels. To complete these studies we have been developing techniques such as Laser Doppler flowmetry in conscious rats, intravital microscopy of the brain, and neural and vascular cell culture models from adult rats.

Robert Ryan

Robert Ryan

Research Associate I
rpryan@mcw.edu

I’m currently in my 31st year at the Medical College of Wisconsin, and have worked with some of the most distinguished principle investigators the research departments have seen. At this time I’ve been very fortunate to work for Dr. Dave Harder in our studies investigating cerebral blood flow autoregulation in conscious animals which has eliminated the confounding effects of anesthesia on blood flow to the brain. I’m responsible for assisting with the day to day operations of the lab and for the surgical preparation of animals and data collection during our experiments. Some of the current techniques we are using include whisker barrel stimulation, imaging brain cells and measuring cerebral blood flow using two-photon microscopy through a cranial window, as well as measuring H2O2/ATP changes in the brain in real time in response to different antagonist and agonists using biosensor probes.

Recent Publications