Mapping oxygen in the awake mouse brain

.......................................................................................................................................................... iv Foreword and Acknowledgements ................................................................................................................... v PART 1: INTRODUCTION ............................................................................................................... 1 Chapter 1: Oxygen, Metabolism and the Brain ................................................................................................. 2 Section 1 – Cellular metabolism, ATP turnover, and the role of oxygen in these processes ............................. 2 1.1 – Thermodynamics and the central role of ATP in the processes of life ................................................. 2 1.2 – Cellular production of ATP .................................................................................................................... 5 Section 2 – Oxygen in Physiology ..................................................................................................................... 10 2.1 – The physical and chemical properties of oxygen in biological systems .............................................. 10 2.2 – The transport of oxygen from the atmosphere to the mitochondria ................................................. 11 2.3 – Mechanisms of oxygen delivery from the microvasculature to the tissue ......................................... 15 Section 3 – Metabolism, ATP turnover and Oxygen Consumption in the Brain ............................................... 17 Chapter 2: Supply of Blood to the Brain, and our Model Systems. .................................................................. 20 Section 1 – Blood supply to the Brain .............................................................................................................. 20 Section 2 – Our Model Systems ........................................................................................................................ 23 2.1 – The olfactory bulb ............................................................................................................................... 23 2.1.1 – Structure and basic functions .......................................................................................................... 23 2.1.2 – Vascular supply and organisation of the olfactory bulb .................................................................. 25 2.2 – The somatosensory cortex .................................................................................................................. 27 2.2.1 – Structure and basic functions .......................................................................................................... 27 2.2.2 – Vascular supply and organisation of the Somatosensory Cortex .................................................... 30 Chapter 3: Tools and Techniques for measuring Oxygen................................................................................. 33 Section 1 – Measurements of oxygen parameters other than Po2 .................................................................. 33 1.1 – Measurement techniques based on measurement of haemoglobin and So2 .................................... 33 1.2 – Positron Emission Tomography (PET) ................................................................................................. 34 Section 2 – Methods of Measuring Po2 ............................................................................................................ 35 2.1 – Polarographic measurements of Po2 .................................................................................................. 35 2.2 – Electron Parametric Resonance (EPR) oximetry ................................................................................. 36 2.3 – Mass spectrometry for measuring Po2 ............................................................................................... 38 2.4 – Optical methods for determining Po2 ................................................................................................. 38 Chapter 4: The Current Understanding of Oxygen in the Brain ....................................................................... 48 Section 1 What is known of Po2 in the Brain? ................................................................................................ 48 1.1 – Po2 in the human brain ....................................................................................................................... 48 1.2 – Po2 in the mammalian brain............................................................................................................... 48 1.2.1 – Po2 in the brain vasculature ............................................................................................................. 49 1.2.2 – Po2 in brain neural tissue ................................................................................................................. 53 1.2.3 – Relationship of tissue Po2 to vascular Po2........................................................................................ 56 1.3 – The effect of inspired gases and anaesthetics on brain Po2 ............................................................... 57 Section 2 – Conclusion...................................................................................................................................... 57 PART 2: METHODS & PROCEDURES ........................................................................................ 59 Section 1 – Combined 2-photon Imaging and 2PLM for Simultaneous Po2 Measurement, and RBC detection60 Section 2 – Surgical Procedures ....................................................................................................................... 65 Section 3 – Training procedure ........................................................................................................................ 68 Section 4 – Procedure for recording of Po2 and Blood flow Parameters in Awake Mice ................................. 71