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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 132 (1979), S. 69-75 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Single-unit vagal afferent recordings were made on 55 intrapulmonary receptors in 15 anesthetized or decerebrate bullfrogs. Intrapulmonary CO2 concentration and intrapulmonary pressure were controlled independently by unidirectionally ventilating the lungs. No CO2 receptors (insensitive to stretch of the lung) of the kind reported in birds and reptiles were found; all 55 receptors were mechano-sensitive. Of these mechanoreceptors, 39 adapted slowly to inflation of the lung and 16 adapted rapidly. Thirtythree of the slowly-adapting receptors and 15 of the rapidly adapting receptors decreased their discharge frequency as intrapulmonary CO2 concentration was increased. Inflating the lung enhanced CO2 sensitivity. The results indicate that the frog possesses CO2-sensitive pulmonary mechanoreceptors similar to those of mammals and reptiles.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 31 (1975), S. 455-456 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung In der Lunge von Eidechsen (Tupinambis nigropunctatus) wurden unter Anwendung von Einweg-Ventilationsmethoden CO2-sensible Rezeptoren nachgewiesen (afferente Reflexbahn im N. vagus). Plötzliches Absenken der intrapulmonären CO2-Konzentration löst innert 0,8 bis 1,4 sec einen von zwei Ventilations-Mechanismen aus (Atmungsstillstand oder reduzierte Atmungsleistung), wozu jedoch keine Blutdurchströmung der Lungenarterien und-venen notwendig ist.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 402 (1984), S. 162-165 
    ISSN: 1432-2013
    Keywords: Treatmill running ; Pekin ducks ; Arterial chemoreceptors ; Control of breathing ; Exercise hyperpnea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To determine if arterial chemoreceptors contribute to the ventilatory response during exercise, we measured minute ventilation ( $$\dot V$$ 1) in spontaneously breathing Pekin ducks (Anas platyrhynchos) during rest and running exercise when the inspired gas was switched from either 21% or 12% O2 to 100% O2 for 45 s (O2-test). In normoxia at rest (PaO2=99 Torr), inhaling 100% O2 reduced $$\dot V$$ 1 by 30%, while during resting hypoxic conditions, (PaO2=56 Torr), 100% O2 inhalation reduced $$\dot V$$ 1 by 66%. During exercise, abruptly inhaling 100% O2 decreased $$\dot V$$ 1 by only 14% and 33% in normoxic and hypoxic conditions, respectively. Thus, only a small fraction of the ventilatory response during exercise under normoxic conditions is due to an arterial chemoreceptor input. However, during exercise in hypoxic conditions, arterial chemoreceptors provide a substantial portion of the total drive to ventilation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 65 (1992), S. 278-285 
    ISSN: 1439-6327
    Keywords: Viscosity ; Blood rheology ; O2 delivery ; Haemoconcentration ; Exercise ; Packed cell volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Arterial blood samples were obtained from six greyhounds during rest, immediately before, and after a 704-m (7/16th mile) race. Measurements were made of various haematological (red cell count, haemoglobin, packed cell volume, white cell count, plasma proteins) and haemorheological variables. Blood and plasma viscosity were determined at high wall shear stresses (67–200 dynes · cm−2, 670–2000 μN · cm−2) in a 20-μm glass capillary device which was designed to take the diameter dependence of blood viscosity (Fahraeus-Lindgvist effect) into account. Compared to values at rest, substantial haemoconcentration occurred before the race, mainly due to splenic discharge of red cells. Additional haemoconcentration was found after the race. The increase of effective blood viscosity caused by elevation of packed cell volume was greater than the increase in O2 binding capacity resulting from the elevated haemoglobin concentration, suggesting that the haemoconcentration observed in the exercising greyhound does not enhance O2 delivery to skeletal muscle. The main physiological effect of red cell discharge from the contracting spleen appeared to be a consequence of the volume rather than the composition of the circulating blood.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 147 (1982), S. 107-112 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To determine the importance of hyperthermia on exercise hyperpnea in birds, we exercised adult Pekin ducks on a treadmill (3° incline) at an ambient temperature of −5°C for 20 min at 1.47 km/h. At that temperature, ducks maintained constant body temperature throughout exercise. During exercise, tidal volume decreased and respiratory frequency increased, to account for an approximate doubling of minute ventilation. Heart rate and systolic and diastolic blood pressure significantly increased during exercise. ArterialP CO 2 decreased approximately 3 Torr during running while mixed venousPCO 2 increased initially, before returning to control values. Changes in arterial pH during exercise were small. Mixed venous pH markedly decreased at the onset of exercise, then reached a steady value for the remainder of exercise. Mixed venousP O 2 and arterial and mixed venous plasma [HCO 3 − ] decreased during running, while venous [lactic acid] increased approximately 75% over control values. We concluded that ducks hyperventilate during exercise even though body temperature remains constant. Although hyperthermia may play a role in eliciting ventilatory changes with exercise in ducks, other factors also contribute to the overall hypernea.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Fresh-frozen, serial cross-sections of the transversus abdominis muscle of four mature chickens (98 fibers) were examined to determine structural and histochemical characteristics throughout the entire length of skeletal muscle fibers. Fiber diameter and nicotinamide adenine dinucleotide diaphorase (NAD-D) and myosin adenosine triphosphatase (ATPase) activities were used as criteria to classify fibers as Type I or II. Measurements were made at 10 to 22 locations along the length of the fibers. An unimodal distribution of mean fiber diameters ranging from 48 μ to 86 μ was found. Fibers did not appear larger in the belly of the muscle than near the ends. Although small fluctuations in fiber diameter occurred through the length of a fiber, large and small fibers tended to remain relatively large or small at each location. NAD-D activity was either consistently high or low throughout the length of a fiber. Likewise, myosin ATPase activity was either high or low for an entire fiber. It is concluded that skeletal muscle fibers maintain rather uniform structural and histochemical characteristics along their entire length.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 176 (1977), S. 243-249 
    ISSN: 1432-0878
    Keywords: Lung ; Rodent ; Epithelium ; Biogenic amines ; Enterochromaffin cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two distinct populations of fluorogenic amine-containing cells were observed in the lungs of nine-week old mice: one with an intense yellow emission, which possibly indicates the presence of serotonin; and one emitting a yellow-green fluorescence, which probably indicates the presence of a catecholamine such as dopamine or norepinephrine. Simultaneous identification of two different fluorogenic amine-containing cells, without pre-administration of a precursor to that amine, has not previously been reported. Such evidence of amine-containing cells demonstrated the success of the perfusion-freezing technique and established that cellular storage of fluorogenic amines does occur in vivo under normal physiological conditions. The function of such amine-containing cells has not been established; however, their location and the known physiological effects of amines would suggest regional control of ventilation/perfusion of the lung.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A detailed gross anatomical study of the innervation of the respiratory muscles was made on twenty mature, male, Single Comb White Leghorn chickens. The aim was to demonstrate the general pattern and degree of terminal branching of the intercostal and lumbar nerves that innervate respiratory muscles.The point of entry for all nerves was on the medial face of the proximal third of the belly of the muscles, except for the transversus abdominis and costopulmonary muscles. The nerves were not always accompanied by blood vessels at the point of entry but both were invariably related at their terminal branches within the muscle belly and the tendon or aponeurosis. Within the muscle, primary, secondary, tertiary, and quarternary subdivisions of nerves coursed parallel to the muscle fibers, but some were tortuous. Plexus formation and/or segmental nerve anastomosis was most evident in strongly active expiratory and inspiratory muscles, i.e., all abdominal muscles and the m. costisternalis pars major.A craniocaudal gradient in the size and development of the contractile mass of the intercostal muscles was observed. The mm. intercostales interni increased in size in the caudal intercostal spaces, while the reverse was true for the mm. intercostales externi. Variable forms and sizes of lateroventral abdominal muscles were observed and the m. rectus abdominis was consistently present.The mm. intercostales interni and externi received branches from both the nn. intercostales interni and externi.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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