Debebe Gebremedhin, Ph.D.

The major mission of our laboratory is to understand mechanisms regulating the physiology of cerebral circulation in health and in disease conditions. Our research interests involve 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 the interaction between ion channels and lipid mediators, second messengers, hypoxia as well as different enzymatic pathways in regulating functions of the cerebral circulation. We are also investigating the influence of disease states such as insulin-dependent diabetes mellitus and Alzheimer's disease on ion channel function and second messenger systems that could account for alterations in brain function in these disease states. Laser-Doppler flowmetry is used in healthy and diseased subjects to understand if alterations in endogenous mechanisms that influence regulation 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 in culture or using brain slices, brain cerebral blood flow using laser-Doppler flowmetry, biochemical assay of lipid metabolites, reactive oxygen species, protein kinases and protein phosphatases, molecular analysis of ion channels, receptors and P450 enzymes.

Recent Publications:
Drummond HA, Gebremedhin D, Harder DR. Degenerin/epithelial Na+ channel proteins: components of a vascular mechanosensor. Hypertension. 2004 Nov;44(5):643-8.

Yu M, Cambj-Sapunar L, Kehl F, Maier KG, Takeuchi K, Miyata N, Ishimoto T, Reddy LM, Falck JR, Gebremedhin D, Harder DR, Roman RJ. Effects of a 20-HETE antagonist and agonists on cerebral vascular tone. Eur J Pharmacol. 2004 Feb 23;486(3):297-306.

Gebremedhin D, Yamaura K, Zhang C, Bylund J, Koehler RC, Harder DR. Metabotropic glutamate receptor activation enhances the activities of two types of Ca2+-activated k+ channels in rat hippocampal astrocytes. J Neurosci. 2003 Mar 1;23(5):1678-87.

Harder DR, Zhang C, Gebremedhin D. Astrocytes function in matching blood flow to metabolic activity. News Physiol Sci. 2002 Feb;17:27-31. Review.

Gebremedhin D, Lange AR, Lowry TF, Taheri MR, Birks EK, Hudetz AG, Narayanan J, Falck JR, Okamoto H, Roman RJ, Nithipatikom K, Campbell WB, Harder DR. Production of 20-HETE and its role in autoregulation of cerebral blood flow. Circ Res. 2000 Jul 7;87(1):60-5.