Cardiovascular Center

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Debebe Gebremedhin, BPharm., Ph.D.
Associate Professor, Physiology

Phone: (414) 955-5715

 

Research Areas

Cardiovascular Physiology, Neurophysiology, Molecular and Cellular Physiology

The mission of our laboratory is to understand mechanisms regulating physiology of the cerebral circulation in health and in disease conditions. Our research interests involve functional identification and characterization of different ion channel types and second messenger systems in vascular smooth muscle cells, endothelial cells, neurons and in brain astrocytes. Studies in the laboratory mainly focus on examining interactions between ion channels and lipid mediators, reactive oxygen species, second messenger systems as well as oxygen deprivation in regulating functions of the cerebral circulation. We also investigate the influence of disease states such as insulin-dependent diabetes mellitus, Alzheimer's disease and transient ischemic stroke on ion channel expression and function, and on second messenger systems that could account for vascular and/or neuronal dysfunction in the brain. Cerebral blood flow measured by Laser-Doppler flowmetry is also used as a surrogate of brain function in healthy and diseased subjects to understand if alterations in levels and activities of diverse endogenous mediators and their targets influence dynamics of cerebral blood flow. Our research areas include patch clamp analysis of ion channel currents in the cerebral and coronary vascular smooth muscle cells, endothelial cells neurons and astrocytes or in acute brain slices, monitoring cerebral blood flow using laser-Doppler flowmetry, biochemical assay of lipid metabolites CYP enzymes, proteins, reactive oxygen species, different kinases and phosphatases, molecular analysis of ion channels, and adenosine actions in the brain.

Selected Recent Publications

  • Gebremedhin D, Yamaura K, Harder DR (2008). Role of 20-HETE in the hypoxia-induced activation of Ca2+-activated K+ channel currents in rat cerebral arterial muscle cells. Am. J. Physiol. (Heart and Circ. Physiol.) 294:H107-H120.
  • Zagorac D, Jakovcevic D, Gebremedhin D, Harder DR (2008). Anti-angiogenic effects of inhibitors of cytochrome P450 on rats with glioblastoma multiforme. J. Cereb. Blood Flow Metab. 28(8):1431-9.
  • Medhora M, Chen Y, Gruenloh S, Bodiga S, Zielonka J, Gebremedhin D, Gao Y, Falck J, Jacobs ER (2008). 20-HETE increases superoxide production, activates NADPH oxidase, and increases expression of NADPH oxidase in pulmonary artery endothelial cells. (Submitted to Am. J. Physiol. Lung Cell. Mol. Physiol. 294:L902-L911.
  • Shi Y, Kiu X, Gebremedhin D, Falck JR, Harder DR, Koehler RC (2008). Interaction of mechanisms involving epoxyeicosatrienoic acids and adenosine and metabotropic glutamate receptors in neurovascular coupling in rat whisker barrel cortex. J. Cereb. Blood Flow Metab. 28:111-125.
  • Yamaura K, Gebremedhin D, Zhang C, Narayanan J, Hoefert K, Jacobs ER, Raymond CK, Harder DR. Contribution of epoxyeicosatrienoic acids in the hypoxia-induced activation of Ca2+-activated K+ channel currents in cultured rat hippocampal astrocytes. Neuroscience 2006, 143:703-718).
  • Koehler CK, Gebremedhin D, DR Harder, Role of astrocytes in cerebrovascular regulation. J. Appl. Physiol. 2006, 100:307-317. 
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