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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 336 (1972), S. 217-224 
    ISSN: 1432-2013
    Keywords: H2 Clearance ; Carotid Body ; Blood Flow ; Chemoreceptor Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A technique is described which enables the determination of local blood flow in different points of the carotid body. The blood flow measured in the middle zone of the catorid body at mean blood pressure of 120 to 130 mm Hg was about 2000 ml/100 gxmin and corresponded to the total flow values known thus far. It was found that the flow/g weight decreases from the arterial inflow towards the periphery. Under our experimental conditions no signs of autoregulation could be detected. Under special experimental conditions differnnt flow distributions were observed in the carotid body.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Brain cortex ; Blood-free perfusion ; $$P_{O_2 }$$ needle electrodes ; Oxygen supply ; Hypothermia ; $$P_{O_2 }$$ histogram of brain tissue ; $$P_{O_2 }$$ histogram of pial surface ; Mean local tissue $$P_{O_2 }$$
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The O2 supply of the blood-free perfused brain cortex of the guinea pig was investigated by measuring polarographically the local distribution of tissue $$P_{O_2 }$$ at 18°C, 24°C, and 37°C. The perfusion was performed in situ, using a medium equilibrated by a gas mixture of 95% O2 and 5% CO2. Papaverine was added to prevent vasoconstriction during hypothermia. To avoid measuring artefacts thin micro electrodes with a small sharpened tip of ca. 4 μm in diameter were used and a special puncturing technique was applied. The experimental results indicate the presence of a large variation of local tissue $$P_{O_2 }$$ . Local mean $$P_{O_2 }$$ increased up to a depth of 1000 μm, reached a plateau, and then decreased towards 3000 μm. This demonstrates that the O2 supply changes in dependence of the distance of the brain surface. This may partly becaused by the special vascularization pattern of the brain cortex. As it follows from the $$P_{O_2 }$$ histograms, at 24°C the tissue layer between 0–2000 μm (layer I) was well supplied with oxygen, whereas at the same time the layer between 2001–3000 μm (layer II) was hypoxic. At 37°C, both layers were hypoxic, but layer III showed the more pronounced tissue hypoxia. To obtain a sufficient oxygen supply the temperature had to be reduced below 24°C to sufficiently decrease tissue O2 consumption: at 18°C, there was no sign of hypoxia any more. In comparison with the $$P_{O_2 }$$ histogram of the tissue the $$P_{O_2 }$$ histogram of the pial surface was shifted to higher $$P_{O_2 }$$ values. The experiments show that in the blood-free perfused guinea-pig brain the $$P_{O_2 }$$ histogram of the surface or of the upper tissue layer were not representative for the deeper layers. This has to be taken into account, when comparing results of tissue $$P_{O_2 }$$ measurements with results of biochemical or photometric brain tissue investigations.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Microfluorescence photometry ; Microreflectance photometry ; Tissue fluorescence ; NADH-fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The construction of a microscope photometer using prefabricated elements is described. To illuminate the tissue, a Leitz Ultropac is applied. To enlarge the wavelength range, its illuminating glass lens is replaced by an Acryl glass zonal lens. Two separate light channels with separate lamps, monochromators and photomultipliers allow the measurement of fluorescence excitation and emission spectra as well as of reflection spectra. By chopping the light, light pulses and dark currents are measured 8.33 times a second. By an integration circuit the signal-to-noise ratio for small signals is improved. The instrument allows us to detect the increase of 4 ng/ml NADH (solution of pH 7.38) in an area of 0.2 mm2.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2013
    Keywords: pO2 ; Rabbit carotid body ; Chemoreceptive process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the specific tissue of the rabbit carotid body as well as in the connective tissue surrounding the organ,pO2 distribution was measured with membranecovered needle electrodes (tip diameter 1–2 μm). The histograms resulting from measurements in the specific tissue were shifted to lowpO2 values as compared to other tissues. The oxygen blowing test, i.e. exposure of the carotid boyd to humidified 100% oxygen was employed to decide upon the site of measurement:pO2 increased when the electrode measured in the surrounding tissue (type 1 response);pO2 remained stable or slightly decreased when the electrode sampled in the specific carotid body tissue (type 2 response). After the experiment, the electrode track was reconstructed from histological serial sections and the type of reaction was related to the type of tissue. LowpO2 values were found to prevail in the specific carotid body tissue, which leads to the conclusion that the amount of lowpO2 values determines the degree of chemoreceptor activity.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 243 (1962), S. 312-312 
    ISSN: 1432-1912
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1440
    Keywords: Transcutaneous $$P_{O_2 }$$ ; Transcutaneous $$P_{CO_2 }$$ ; in vivo determination of the local capillary Hb concentration ; Bloodless Determination of the Arterial $$P_{O_2 }$$ and $$P_{CO_2 }$$ , Bloodless Determination of the Acid/Base Status ; Transcutane $$P_{O_2 }$$ ; transcutaner $$P_{CO_2 }$$ ; in vivo-Bestimmung der lokalen capillären Hämoglobinkonzentration ; unblutige Erfassung der Blutgase ; unblutige Erfassung des Säure-Basen-Status
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Arterielle Blutgaswerte lassen sich transcutan erfassen, wenn die Perfusionseffizienz der Haut so hoch ist, da\ kleine Änderungen der Durchblutung den gemessenen $$P_{O_2 }$$ - und $$P_{CO_2 }$$ -Wert nicht verändern. Dies läßt sich mit speziell konstruierten, thermostatisierten und geheizten $$P_{O_2 }$$ - und $$P_{CO_2 }$$ -Elektroden erreichen. Die zur Temperatur-regelung notwendige Heizleistung ist ein Maß für die Perfusion, die gleichzeitige Veränderung des $$P_{O_2 }$$ oder $$P_{CO_2 }$$ ein Maß für die Effizienz. Ist der arterielle $$P_{O_2 }$$ und $$P_{CO_2 }$$ bekannt, so läßt sich der Säure-Basen-Status nach der bekannten Methode der Blutnomographie bestimmen.
    Notes: Summary Arterial blood gas values can be monitored transcutaneously, if the perfusion efficiency of the skin is so high that small changes in blood flow do not change the measured $$P_{O_2 }$$ and $$P_{CO_2 }$$ values. This is brought about by specially constructed $$P_{O_2 }$$ and $$P_{CO_2 }$$ electrodes which are heated and thermostated. The power necessary to regulate the temperatures of the electrode serves as an index of the perfusion, the simultaneous change of the transcutaneous $$P_{O_2 }$$ and $$P_{CO_2 }$$ as an index of efficiency. Knowing the arterial $$P_{O_2 }$$ and $$P_{CO_2 }$$ , the acid/base status can be determined by applying the well known methods of blood nomography.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 57 (1970), S. 42-42 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 57 (1970), S. 134-134 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 57 (1970), S. 311-311 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 58 (1971), S. 321-321 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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