This monograph contains the proceedings of a symposium entitled, "Tissue Hypoxia and Ischemia," which was held at the Annenberg Center of the University of Pennsylvania on August 13 and 14, 1976. The symposium was jointly sponsored by the following groups at the University of Pennsylvania: the Respiratory Physiology Group of the Department of Physio­ logy, the Cardiopulmonary Section of the Department of Medicine, the Johnson Research Foundation, the Cerebrovascular Research Center of the Department of Neurology, the Head Injury Center of the Department of Neurosurgery, the. Institute for Environ­ mental Medicine, and the International Society on Oxygen Transport to Tissues. Its purpose was to promote an interdisciplinary discussion of oxygen sensors in various tissues and their mechanism of action as well as to examine the deleterious effects of hypoxia and ischemia with special reference to the brain. There were four sessions, one on the biochemistry of physi­ ologic oxygen sensors, two on the mechanism of oxygen sensing in tissues and one on the circulatory and metabolic aspects of cerebral hypoxia and ischemia.

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The Biochemistry of Physiologic Oxygen Sensors.- What is a molecular oxygen sensor? What is a transduction process?.- The oxygen sensing characteristics of microsomal enzymes.- Oxygen sensing heme proteins: monoxygenases, myoglobin and hemoglobin.- Peroxisomal enzymes and oxygen metabolism in liver.- Mitochondrial production of superoxide radical and hydrogen peroxide.- Mechanism of Oxygen Sensing in Tissues.- Chemoreception and transduction on neuronal models.- Oxygen tension sensors in vascular smooth muscle.- Comments on: oxygen tension sensors in vascular smooth muscle.- Mechanism of oxygen induced contraction of ductus arteriosus.- Prostaglandins and the control of muscle tone in the ductus arteriosus.- The sensing of oxygen tension in the pulmonary circulation.- The sensing of oxygen tension in the pulmonary circulation. Discussion.- Circulatory effects of tissue oxygen tension sensors.- Bioassay and pharmacologic evaluation of the adenosine hypothesis.- Mechanism of Oxygen Sensing in Tissues.- Introductory remarks: oxygen linked response of carotid chemoreceptors.- Convergence of stimuli in arterial chemoreceptors.- Intracellular studies of carotid body cells: effects of temperature, "natural" stimuli and chemical substances.- Tissue PO2 in the cat carotid body and related functions.- Some aspects of localization, depletion, uptake and turnover of catecholamines by glomus cells of the rat carotid body.- Catecholamines and 3?,5? cyclic amp in carotid body chemoreception in the cat.- Circulatory and Metabolic Aspects of Cerebral Hypoxia-Ischemia.- Metabolic aspects of cerebral hypoxia-ischemia.- Discussion: metabolic aspects of cerebral hypoxia-ischemia.- Regional changes in metabolism in hypoxia-ischemia.- Cyclic nucleotide levels in the gerbil cerebral cortex, cerebellum and spinal cord following bilateral ischemia.- Changes in PO2 and ion fluxes in cerebral hypoxia-ischemia.- Comments on: changes in PO2 and ion fluxes in cerebral hypoxia-ischemia.- Events marking irreversible injury.- Cerebral hemodynamic and metabolic alterations in stroke.- Cerebral hemodynamic and metabolic alterations in stroke: formal discussion of paper by Dr. Martin Reivich, et al..- Cerebral hemodynamic and metabolic alterations in hypovolemic shock.- Altered mitochondrial metabolism in circulatory shock.- Discussion of Presentation by A.G.B. Kovach.- Participants.