Advances in Physiological Sciences, Volume 25: Oxygen Transport to Tissue covers the proceedings of the satellite symposium of the 28th International Congress of Physiological Science, held in Budapest, Hungary in 1980. This book mainly focuses on the relation of oxygen transport and delivery to heterogeneities, autoregulation of blood flow, organ function, and rheology. This compilation is divided into five sessions. The first two sessions encompass the models and experiments on the relationship between oxygen transport and heterogeneities. The subsequent session presents papers concerned with autoregulation of blood flow and oxygen delivery. The last two sessions are devoted to presenting papers on oxygen transport and organ function and rheology and oxygen transport. This compendium will be invaluable to those studying oxygen transport and its relationship with other biological processes.

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Yes, you can access Oxygen Transport to Tissue by A. G. B. Kovách,E. Dóra,M. Kessler in PDF and/or ePUB format, as well as other popular books in Medicine & Physiology. We have over one million books available in our catalogue for you to explore.

Information

Publisher

Pergamon

Year

2013

ISBN

9781483190167

Topic

Medicine

Subtopic

Physiology

SESSION IV

OXYGEN TRANSPORT AND ORGAN FUNCTION

Outline

Chapter 49: TISSUE OXYGENATION AND TISSUE METABOLISM IN THE BRAIN CORTEX DURING PRONOUNCED ARTERIAL HYPOCAPNIA

Chapter 50: CONTROL MECHANISMS INVOLVED IN THE REGULATION OF CEREBRAL TISSUE PRESSURE IN OXYGEN

Chapter 51: TISSUE OXYGENATION AND NORMAL AND HYPERTHERMIC CONDITIONS

Chapter 52: NAD-NADH AND VASCULAR VOLUME OSCILLATIONS IN THE CAT BRAIN CORTEX

Chapter 53: RESISTANCE TO BLOOD FLOW IN DENERVATED CANINE HINDLIMB DURING HYPOXIA

Chapter 54: OXYGEN CONSUMPTION BY DRONE PHOTORECEPTORS IN DARKNESS AND DURING REPETITIVE STIMULATION WITH LIGHT FLASHES

Chapter 55: THE DISTRIBUTION OF RBC VELOCITY IN CAPILLARIES OF RESTING SKELETAL MUSCLE

Chapter 56: REACTIVITY AND REGENERABILITY OF THE CARDIO-PULMONARY SYSTEM. THE ARTERIAL pO2 AS A DIAGNOSTIC PARAMETER

Chapter 57: PHYSIOLOGIC ADAPTION OF MYOCARDIAL CONTRACTILE STRENGTH AS DETERMINED BY DIRECT CHANGES IN MYOCARDIAL METABOLISM INDEPENDENT OF HEMODYNAMIC LOADING

Chapter 58: OXYGEN TENSION IN RELATION TO ENERGY METABOLISM IN EXERCISING HUMAN SKELETAL MUSCLE

Chapter 59: OPPOSITE CHANGES IN THE REDOX STATE OF THE BRAIN CORTEX DEPENDING ON THE LENGTH AND STRENGTH OF DIRECT CORTICAL STIMULATION

Chapter 60: OXYGEN SUPPLY OF THE BRAIN CORTEX (RAT) DURING SEVERE HYPOGLYCEMIA

Chapter 61: SKELETAL MUSCLE SURFACE OXYGEN PRESSURE FIELDS IN HUMANS

Chapter 62: TISSUE pH-DISTRIBUTION WITHIN MALIGNANT TUMORS AS MEASURED WITH ANTIMONY MICROELECTRODES

Chapter 63: INTRA-AMNIOTIC INJECTION OF AN OXYGEN CARRIER (PERFLUOROTRIBUTYLAMINE) DURING THE LAST STAGES OF THE RAT FETAL DEVELOPMENT

Chapter 64: EFFECT OF CALCIUM AND NICKEL IONS ON GLYCOLYTIC AND OXIDATIVE METABOLISM AND CONTRACTILITY OF THE RAT UTERUS

Chapter 65: BLOOD O2 DISSOCIATION CURVE AND O2 TRANSPORT TO THE ISOLATED AND PERFUSED TURTLE HEART

Chapter 66: MICROCIRCULATION AND OXYGEN AVAILABILITY IN THE BRAIN CORTEX AT DEPRESSED ELECTRICAL ACTIVITY

Chapter 67: METABOLIC STEADY STATES IN THE UTERUS

Chapter 68: EFFECT OF OXYGEN ON HISTOTOXIC HYPOXIA CAUSED BY CYANIDE

Chapter 69: THE EFFECT OF ACETAZOLAMIDE ON BRAIN O2 METABOLISM

Chapter 70: THE INFLUENCE OF TRAUMATIC TOXAEMIA ON THE CORTICOSTEROID LEVEL AND ON THE ACTIVITY OF MITOCHONDRIAL ENZYMES

Chapter 71: DISCUSSION AND SUMMARY SESSION IV OXYGEN TRANSPORT AND ORGAN FUNCTION

TISSUE OXYGENATION AND TISSUE METABOLISM IN THE BRAIN CORTEX DURING PRONOUNCED ARTERIAL HYPOCAPNIA

J. Grote, R. Schubert and K. Zimmer, Department of Applied Physiology and Department of Neurosurgery, University of Mainz, 65 Mainz, FRG

Publisher Summary

This chapter describes the tissue oxygenation and tissue metabolism in the brain cortex during pronounced arterial hypocapnia. Acute arterial hypocapnia induced by hyperventilation leads to typical reactions in the circulation and the metabolism of the brain tissue. With a lowering of arterial CO₂ tension, the cerebro-vascular resistance (CVR) increases resulting in a decrease of cerebral blood flow. The changes in CVR are a consequence of decreasing hydrogen ion and potassium ion concentrations in the perivascular space of the brain arterioles. The corresponding changes in the brain metabolism are characterized by elevated concentrations of lactate and pyruvate and an increase in the lactate/pyruvate ratio as well as an increase in the NADH level and in the NADH/NAD⁺ ratio in the brain tissue. The effects of arterial hypocapnia on the nerve cell metabolism and electrical activity can be attributed to the decrease in tissue PCO₂. In addition, there is evidence that these changes are in part a result of insufficient blood flow because of cerebral vasoconstriction occurring during hyperventilation. Previous measurements of mean tissue PO₂ and metabolites suggest that arterial hypocapnia may lead to ischemic hypoxia in small dispersed areas of the brain tissue. The decrease of PaCO₂ to 2.5 kPa produced a rapid reduction of cortical blood flow. At the same time, because of the blood flow changes and in minor part to the displacement of the blood O₂ dissociation curve to the left, the PO₂ histograms of the cortical tissue shifted to lower values.

Acute arterial hypocapnia induced by hyperventilation leads to typical reactions in the circulation and the metabolism of the brain tissue. With a lowering of arterial CO₂ tension the cerebro-vascular resistance (CVR) increases resulting in a decrease of cerebral blood flow (CBF). The Changes in CVR are a consequence of decreasing hydrogen ion and potassium ion concentrations in the perivascular space of the brain arterioles (see reviews by: Betz, 1972; Edvinsson and MacKenzie, 1977; Kuschinsky and Wahl, 1978). The corresponding changes in the brain metabolism are characterized by elevated concentrations of lactate and pyruvate and an increase in the lactate/pyruvate ratio, as well as an increase in the NADH level and in the NADH/NAD⁺ ratio in the brain tissue (Leusen and Demeester, 1966; Plum and Posner, 1967; Hohorst et al., 1968; Granholm and Siesjö, 1969, 1971; Granholm et al., 1969; Betz, 1972; Rubio et al., 1975).

Additionally, with the changes in CBF and brain metabolism high voltage slow waves in the EEG are observed (e. g. Meyer and Gotoh, 1960; Alexander et al., 1965).

The effects of arterial hypocapnia on the nerve cell metabolism and electrical activity can be attributed to the decrease in tissue PCO₂,(s. Granholm and Siesjö, 1969). In addition, there is evidence that these changes are in part a result of insufficient blood flow due to cerebral vasoconstriction occuring during hyperventilation. Previous measurements of mean tissue PO₂ and metabolites suggest that arterial hypocapnia may lead to ischemic hypoxia in small dispersed areas of the brain tissue (Meyer and Gotoh, 1960; Alexander et al., 1965; Hohorst et al., 1968; Granholm and Siesjö, 1969, 1971; Pickeroth, 1971; Betz, 1972; Rubio et al., 1975). It was assumed that the increase of the lactate/pyruvate ratio and the NADH/NAD⁺ ratio may reflect the insufficient oxygen supply state of the brain cortex. However, since at the same time the tissue concentrations of PCr and ATP were found to be normal, this assumption could not be made with certainty. In order to insure that tissue hypoxia at very low PaCO₂ is present, a determination of the brain tissue oxygen tension distribution or the demonstration of depleted tissue stores of energy-rich phosphates is necessary. The present experiments were designed to study the influence of a pronounced arterial hypocapnia on regional blood flow, tissue PO₂ distribution and tissue metabolism in the brain cortex of cats.

METHODS

Thirteen cats of both sexes, weighing 2.8 to 4.5 kg, were premedicated with Ketanest (10 − 20 mg•kg⁻¹) and anaesthetized with sodium pentobarbital (Nembutal; 25 mg-kg⁻¹ i. v.). The tracheotomized animals after immobilization with Imbetril (1.6 − 2.0 mg initially and during the experiments 0.2 − 0.3 mg every 30 min) were ventilated with a Starling type respirator. At the beginning of each experiment the output from the respiratory pump was adjusted to produce arterial normoxia and normocapnia during which the control values for regional cortical blood flow and tissue PO₂ were determined. After completion of the initial measurements the animals were hyperventilated to reach constant arterial CO₂ tensions of about 2.7 kPa (20 mmHg) and 1.6 kPa (12 mmHg) at normal arterial oxygen tension. Both hypocapnia levels were maintained for 45 − 60 min. In order to ass...

Cover image
Title page
Table of Contents
ADVANCES IN PHYSIOLOGICAL SCIENCES
Copyright
PREFACE
SESSION I: HETEROGENEITIES AND O2 TRANSPORT, MODEL AND EXPERIMENTAL
SESSION II: HETEROGENEITIES AND O2 TRANSPORT, MODEL AND EXPERIMENTAL
SESSION III: AUTOREGULATION OF BLOOD FLOW AND O2 DELIVERY
SESSION IV: OXYGEN TRANSPORT AND ORGAN FUNCTION
SESSION V: RHEOLOGY AND OXYGEN TRANSPORT
INDEX