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  • Haemocyanin  (3)
  • Locomotion  (2)
  • AC-ECD  (1)
  • Springer  (6)
  • Munksgaard International Publishers
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  • Springer  (6)
  • Munksgaard International Publishers
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  • 1
    ISSN: 1432-136X
    Keywords: Crustacea ; Amphipoda ; Haemocyanin ; Temperature sensitivity ; l-Lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of pH, temperature, and l-lactate on the O2 bindign properties of haemocyanin (Hc) from three talitroidean species i.e., the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana was studied. The Hc of A. pugettensis was characterized by a higher O2 affinity (and more pronounced Bohr shift) than the Hc of either M. californiana or T. traskiana. Apohyale was the only species that possessed He that was sensitive to temperature change. Resuspending Hc from each of the three species in a stock Ringer's solution (based on the ionic composition of the haemolymph of T. traskiana) showed that the persistence of the difference in Bohr shift between Apohyale and the other two species was due to differences in the haemocyanins themselves and not attributable to their respective ionic environments. An inverse relationship was found between the cooperativity (n 50) and pH of Hc from T. traskiana and A. pugettensis but not for M. californiana. In each case adding l-lactate increased Hc O2 affinity, but this was most pronounced for A. pugettensis.
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  • 2
    ISSN: 1432-136X
    Keywords: Crustacea ; Amphipoda ; Haemocyanin ; O2 transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Haemolymph PO2 and pH of two amphipod species, Apohyale pugettensis (aquatic) and Megalorchestia californiana (semi-terrestrial) in vivo were examined during immersion and emersion at 15 and 25°C, and also after activity in air at 15°C. For M. californiana arterial O2 tensions were higher in air than in water. This situation was reversed in A. pugettensis, although all O2 tensions measured for both species were comparatively high. No arterial-venous PO2 difference was apparent in the haemolymph of quiescent M. californiana. Haemocyanin (Hc) was 100% saturated in vivo only in the following; A. pugettensis in water (15 and 25°C) and air (15°C), and M. californiana in air (15°C). The Hc of both species becomes important in O2 transport during activity; under such circumstances the haemolymph of M. californiana delivered more O2 to the tissues than did that of A. pugettensis, despite the greater O2 content of the latter. The animals studied here may exhibit a stage (size class?) where cutaneous gas exchange is sufficient for resting aerobic metabolism while specialized respiratory carriers (and respiratory structures) are important in meeting the increased aerobic demands of activity or environmental stress.
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  • 3
    ISSN: 1432-136X
    Keywords: Amphipoda ; Crustacea ; Haemocyanin ; Freezing ; Inorganic effectors ; Urate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of variations in [K], [Ca], [Mg], [NaCl], and [urate] on the in vitro O2 binding properties of haemocyanin (Hc) from three talitroidean species, viz. the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana were studied. Freezing altered the cooperativity of Hc from A. pugettensis and M. californiana but not T. traskiana. Variations in [NaCl], [K], and [Mg] had no effect on cither O2 affinity or cooperativity of the Hc except for A. pugettensis Hc where an increase in [Mg] resulted in an increase in both O2 affinity and cooperativity. Increasing [Ca] or [urate] increased O2 affinity of both A. pugettensis and M. californiana but not T. traskiana Hc. These effects were most marked in A. pugettensis. The results suggest a negative correlation between sensitivity to Hc effectors and the degree of terrestrial adaptation of a particular amphipod species.
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  • 4
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    Springer
    Microchimica acta 96 (1988), S. 11-26 
    ISSN: 1436-5073
    Keywords: electron capture detector (ECD) ; electron oscillation ; AC-ECD ; argon-methane ; non-homogeneous ECD kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oscillation of electrons—as driven by AC polarization—can be used to extract a high-sensitivity signal from a conventional electron capture detector. For example, hexachloroethane was detected at a hypercoulometric ratio of 2.0 F/mol, down to ca. 60 fg/s (S/N=3) and with a linear range in excess of two orders of magnitude. The change in carrier gas from nitrogen to argon-methane produced the expected order-of-magnitude increase in optimum oscillation frequency. Anab initio simulation of potentials and ion populations in a heterogeneous electron capture system under a high-frequency AC regime provided further insight into the detector's mechanism: Hypercoulometric response is mainly caused by increased cation-electron recombination in the plasma region, owing to a decreased field gradient and an increased cation concentration.
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  • 5
    ISSN: 1432-2072
    Keywords: Key words Dopamine ; Microdialysis ; Nucleus accumbens ; Feeding ; Locomotion ; Area under the curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The intent of the present study was to determine the effects of systemic injections of the sympathomimetic agent ephedrine (EPH) on extracellular dopamine (DA) levels within the rat nucleus accumbens (NAC) and to compare these effects with those of EPH on locomotion and on feeding. In experiment 1, adult male rats were prepared with an indwelling 3 mm microdialysis probe positioned within the NAC. The rats were injected (IP) with vehicle, 5, 10, or 20 mg/kg (–)-EPH with dialysates collected every 20 min for 100 min after drug injection. Systemic injections of 5, 10 or 20 mg/kg (–)-EPH significantly enhanced extracellular levels of NAC DA over baseline by 79%, 130%, and 400%. Systemic injection of 20 mg/kg EPH significantly reduced NAC levels of DOPAC and HVA by 37% and 31%. The effects of EPH on brain dopamine activity were stereospecific given that an additional group of rats injected with 20 mg/kg (+)-EPH exhibited smaller changes in NAC DA (〈25%), DOPAC (〈10%), and HVA levels (〈20%) than did rats injected with 20 mg/kg (–)-EPH. In experiment 2, adult male rats were injected (IP) with 0, 5, 10, or 20 mg/kg (–)-EPH prior to placement in automated activity chambers. Total distance traveled was significantly increased by 10 and 20 mg/kg (–)-EPH, but not by 5 mg/kg (–)-EPH. In experiment 3, adult male rats were injected (IP) with 0, 2.5, 5, or 10 mg/kg (–)-EPH or with 0, 2.5, 5, or 10 mg/kg (+)-EPH prior to a 30-min feeding test. Although each EPH enantiomer decreased feeding, (–)-EPH was more potent in feeding suppression than was (+)-EPH. The present results suggest that EPH may alter locomotion and feeding via an indirect action on brain dopamine activity.
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  • 6
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Dopamine ; Ephedrine ; Locomotion ; Rat ; Sensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Systemic injection of the sympathomimetic agent ephedrine (EPH) stimulates locomotion in drug-naive rats, an effect that may be dependent on the enantiomer of EPH employed [(–)-EPH or (+)-EPH]. The present experiments examined the effects of repeated EPH exposure on locomotion in rats to assess whether these treatments result in drug tolerance or sensitization. In experiment 1, adult male rats were injected once daily with 0, 10, 20, or 40 mg/kg (–)-EPH (IP) on each of 11 days. Locomotor activity was assessed for 60 min after drug injection. Acute exposure to (–)-EPH treatment increased locomotion for animals receiving 20 or 40 mg/kg, and this effect was augmented after 11 days of drug administration. A vehicle-only injection was given to all animals on day 12 to determine the influence of environmental cues on sensitization. On day 13, all rats were injected with 10 mg/kg cocaine HCl to assess whether repeated (–)-EPH exposure produced a cross-sensitization to cocaine (10 mg/kg, IP). Only rats treated repeatedly with 40 mg/kg (–)-EPH exhibited increases in cocaine-stimulated locomotion relative to saline-treated rats. In experiment 2, repeated exposure to (+)-EPH, 40 mg/kg, but not 20 mg/kg, increased activity and demonstrated the development of sensitization. Cross-sensitization to cocaine (10 mg/kg, IP) was not evident following treatment with either concentration of (+)-EPH. There was no evidence that contextual events alone played a role in the effects observed here.
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