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Raymond C. Koehler, Ph.D.

Raymond C. Koehler, Ph.D.

  • Professor of Anesthesiology and Critical Care Medicine

Research Interests

Cardiac arrest and resuscitation; Stroke; Hepatic encephalopathy; Cerebrovascular physiology; Mechanisms of oxygen regulation more


Dr. Raymond Koehler is a professor of anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine. He holds a joint appointment in the Department of Environmental Health Sciences at the Bloomberg School of Public Health at Johns Hopkins.

His research focuses on cerebrovascular physiology and cerebral ischemic injury that arises from stroke and cardiac arrest.

Dr. Koehler received a combined B.S./M.E. in electrical engineering from Rensselaer Polytechnic Institute, and went on to complete a Ph.D. in physiology at the State University of New York at Buffalo. After completing a fellowship in the Department of Environmental Health Sciences at Johns Hopkins, he joined the Johns Hopkins faculty in 1980 as an assistant professor of anesthesiology and critical care medicine. He became an associate professor in 1986 and rose to professor in 1996.

Dr. Koehler has published extensively and has presented his work internationally at numerous conferences and symposia. He sits on the editorial board of the journal Stroke and is a member of American Physiological Society, the American Heart Association, the International Society of Cerebral Blood Flow and Metabolism, the Society for Neuroscience and the Society of Critical Care Medicine. more


  • Professor of Anesthesiology and Critical Care Medicine

Departments / Divisions



  • B.S.; Rensselaer Polytechnic Institute (New York) (1971)
  • M.E.; Rensselaer Polytechnic Institute (New York) (1971)
  • Ph.D.; SUNY University at Buffalo (New York) (1978)

Additional Training

  • Johns Hopkins University, Baltimore, MD, 1980, Environmental Health Sciences

Research & Publications

Research Summary

Dr. Koehler is conducting basic and preclinical translational research in the areas of cerebrovascular physiology and cerebral ischemic injury that arises from stroke and cardiac arrest. His lab uses the filament model of transient middle cerebral artery occlusion to investigate physiologic and pathophysiologic mechanisms that underlie stroke. It is already known that the formation of reactive oxygen species after stroke damages DNA, which leads to the activation of poly(ADP-ribose) and formation of poly(ADP-ribose) polymers. In partnership with researchers in the Institute of Cell Engineering at Johns Hopkins, Dr. Koehler and his colleagues are investigating how release of these polymers from the nucleus triggers the release of apoptosis-inducing factors from the mitochondria and causes neuronal cell death.

Related areas of investigation include ischemic preconditioning, ways to improve tissue oxygenation, mechanisms of abnormal cerebrovascular reactivity after ischemia.

In addition to ischemic stroke, Dr. Koehler is studying mechanisms of term neonatal hypoxic-ischemic encephalopathy in a newborn model of asphyxia. His lab is tailoring therapies to selectively vulnerable striatum, where neurons die rapidly and hypothermia loses its efficacy when induction is delayed. The lab is evaluating drugs that can be administered soon after resuscitation from asphyxia for their potential to extend the therapeutic window of hypothermia. Dr. Koehler also hopes to unravel the mechanisms that couple an increase in cerebral blood flow to neuronal activity.

Dr. Koehler is also investigating the use of multimodality monitoring of indices of autoregulation to spontaneous changes in cerebral perfusion pressure.

Selected Publications

  1. Qin X, Kwansa H, Bucci E, Roman RJ, Koehler RC. “Role of 20-HETE in the pial arteriolar constrictor response to decreased hematocrit after exchange transfusion of cell-free polymeric hemoglobin.” J Appl Physiol 100:336–342, 2006.
  2. Li X, Nemoto M, Xu Z, Yu SW, Shimoji M, Andrabi SA, Haince JF, Piorier GG, Dawson TM, Dawson VL, Koehler RC. “Influence of duration of focal cerebral ischemia and neuronal nitric oxide synthase on translocation of apoptosis-inducing factor to the nucleus.” Neuroscience 144:56-65. 2007.
  3. Yang ZJ, Torbey M, Li X, Bernardy J, Golden WC, Martin LJ, Koehler RC. “Dopamine receptor modulation of hypoxia-ischemic neuronal injury in striatum of newborn piglets.” J Cereb Blood Flow Metab 27(7):1339–51, 2007.
  4. Shi Y*, Liu X*, Gebremedhin D, Falck JR, Harder DR, Koehler RC. “Interaction of mechanisms involving epoxyeicosatrienoic acids, adenosine receptors, and metabotropic glutamate receptors in neurovascular coupling in rat whisker barrel cortex.” J Cereb Blood Flow Metab 28(1):111–125, 2008.
  5. Zhang J, Yang Z-J, Klaus JA, Koehler RC, Huang J. “Delayed tolerance with repetitive transient focal ischemic preconditioning in the mouse.” Stroke 39(3):967–74, 2008.

Contact for Research Inquiries

The Johns Hopkins University School of Medicine
600 North Wolfe Street
Blalock 1404
Baltimore, MD 21287 map
Phone: 410-955-4068
Fax: 410-955-7165

Email me

Activities & Honors


  • American Heart Association
  • American Physiological Society
  • International Society of Cerebral Blood Flow and Metabolism
  • Society for Neuroscience
  • Society of Critical Care Medicine

Professional Activities

  • Editorial board, Stroke
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