Intracerebral gas partial pressure changes under vasoactive drugs

Pinard, Elisabeth; Seylaz, Jacques

doi:10.1007/bf00584144

Cited by 9 publications

(3 citation statements)

References 29 publications

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“…Although the oxygen environment of neural cells has been studied with a variety of techniques (e.g., polarographic electrodes (Lü bbers and Baumgärtl, 1997), mass spectrometric probes (Pinard and Seylaz, 1978), fluorescence (Mitnick and Jobsis, 1976), and phosphorescence (Vanderkooi and Wilson, 1986) quenching probes), a comprehensive understanding to distinguish between unidirectional (E u ) and net (E n ) extraction of oxygen by the brain tissue is still lacking (Figure 1). This is in part because measurements of oxygen partial pressure (pO 2 ) from intravascular (P iv ) and extravascular (P ev ) compartments have not been quantitatively linked to measurements of oxygen consumption (CMR O 2 ) and blood flow (CBF).…”

Section: Introductionmentioning

confidence: 99%

A Multiparametric Assessment of Oxygen Efflux from the Brain

Hermán

Trübel

Hyder

2005

J Cereb Blood Flow Metab

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A quantitative understanding of unidirectional versus net extraction of oxygen in the brain is required because an important factor in calculating oxidative metabolism by calibrated functional magnetic resonance imaging (fMRI) as well as oxygen inhalation methods of positron emission tomography ( 15 O 2 -PET) and nuclear magnetic resonance ( 17 O 2 -NMR)) is the degree of oxygen efflux from the brain back into the blood. Because mechanisms of oxygen transport from blood to brain are dependent on cerebral metabolic rate of oxygen consumption (CMR O 2 ), cerebral blood flow (CBF), and oxygen partial pressure (pO 2 ) values in intravascular (P iv ) and extravascular (P ev ) compartments, we implemented multimodal measurements of these parameters into a compartmental model of oxygen transport and metabolism (i.e., hemoglobin-bound oxygen, oxygen dissolved in plasma and tissue spaces, oxygen metabolized in the mitochondria). In the a-chloralose anesthetized rat brain, we used magnetic resonance (7.0 T) and fluorescence quenching methods to measure CMR O 2 (2.571.0 lmol/g min), CBF (0.770.2 mL/g min), P iv (74710 mm Hg), and P ev (1675 mm Hg) to estimate the degree of oxygen efflux from the brain. In the axially distributed compartmental model, oxygen molecules in blood had two possible fates: enter the tissue space or remain in the same compartment; while in tissue there were three possible fates: enter the blood or the mitochondrial space, or remain in the same compartment. The multiparametric results indicate that the probability of unmetabolized (i.e., dissolved) oxygen molecules reentering the blood from the tissue is negligible and thus its inclusion may unnecessarily complicate calculations of CMR O 2 for 15 O-PET, 17 O-NMR, and calibrated fMRI methods.

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Section: Introductionmentioning

confidence: 99%

A Multiparametric Assessment of Oxygen Efflux from the Brain

Hermán

Trübel

Hyder

2005

J Cereb Blood Flow Metab

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“…These effects of papaverine were still observed when hypoxia or hypercapnia were induced (Haggendal, 1965;Wilson, Traystman & Rapela, 1985). Furthermore it has been shown in cats that not only cerebral blood flow increases but also cortical brain tissue Po is enhanced and tissue PCO2 decreased (Saratikov & Dmitrienko, 1975;Nikolov & Leniger-Follert, 1978;Pinard & Seylaz, 1978). However, we could not find information about the effect of papaverine on the Pt Co2 of the medulla oblongata.…”

Section: Discussionmentioning

confidence: 66%

Effect on ventilation of papaverine administered to the brain stem of the anaesthetized cat.

Berkenbosch¹,

Olievier²,

DeGoede³

et al. 1991

The Journal of Physiology

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SUMMARY1. To investigate whether cerebral vasodilatation by itself contributes to the decrease in ventilation as found during brain stem hypoxia the role of cerebral vasodilatation on minute ventilation was investigated in twelve cats anaesthetized with a-chloralose-urethane.2. Cerebral vasodilatation in the medulla oblongata was produced by adding papaverine to the blood perfusing the brain stem.3. Papaverine at concentrations of 10-35 ,tg per millilitre of blood had an appreciable depressant effect on ventilation. At a concentration of 14-3 jtg ml-' the depression in ventilation averaged 0 7 +0A1 I min-'.4. The ventilatory response to stepwise changes in papaverine concentration could be adequately described with a single exponential function with a time delay.5. The time constant of the ventilatory response following a step increase in papaverine concentration (134+15 s) was longer than that of the step decrease (105 + 10 s) in concentration (P = 0-034). The time delays of the ventilatory response (88 + 21 s and 53 + 8 s respectively) were not significantly different (P = 0 126).6. The ventilatory response to stimulation of the peripheral chemoreceptors by hypoxia and of the central chemoreceptors by hypercapnia was not impaired by papaverine.7. The results support the hypothesis that cerebral vasodilatation by itself contributes to the decrease in ventilation by brain stem hypoxia.

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“…The question was whether catecholamines act on the cerebral vessel's diameter by a direct stimulation of specific receptors or by means of local P C 0 2 changes [9], 24 rabbits were used for this study, and the results are pre sented as the mean variation ± SEM ex pressed as a percentage o f the mean baseline value; these results for cerebral variables con cern the caudate nucleus. An intravenous in jection of adrenaline (1 pg/kg) induces the following changes: Figure 2 shows one example o f this injec tion: o f course, there is an increase in blood pressure which is perhaps responsible for the slight increase in C B F which occurs just be fore a marked vasoconstriction.…”

Section: Application Of the Methodsmentioning

confidence: 99%

Continuous Estimation of Cerebral Metabolic Changes

Pinard¹,

Seylaz²

1981

Eur Neurol

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The purpose of the present research has been to estimate rapid metabolic changes. By means of mass spectrometry, the partial pressures of physiological gases are continuously analyzed in a local area of the brain tissue. The method we have developed allows quantitative measurement of the variables with a response time of less than 1 min. When coupled with continuous measurement of (1) PaO₂ and PaCO₂ by means of mass spectrometry, and (2) cerebral blood flow by thermoclearance, this method is able to indicate rapid metabolic changes when quantitative methods of determining metabolism are not usable.

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Intracerebral gas partial pressure changes under vasoactive drugs

Cited by 9 publications

References 29 publications

A Multiparametric Assessment of Oxygen Efflux from the Brain

A Multiparametric Assessment of Oxygen Efflux from the Brain

Effect on ventilation of papaverine administered to the brain stem of the anaesthetized cat.

Continuous Estimation of Cerebral Metabolic Changes

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