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  • 1
    ISSN: 1432-1912
    Keywords: Neuropeptide Y ; Catecholamines ; Cyclic adenosine monophosphate ; Chromaflin cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of neuropeptide Y [NPY(1–36)] and related peptides on the voltage-dependent currents and the nicotinic acetylcholine receptor (nAChR) currents (IACh) of bovine adrenal chromafptn cells was investigated using the whole-cell patch clamp technique. Catecholamine release from single chromaffin cells was measured by means of fast cyclic voltammetry. The potency order of these peptides in inhibiting IACh evoked by nicotine was NPY(1–36), NPY (16–36) 〉 peptide YY(PYY) 〉 [Leu31, Pro34] NPY. NPY(16–36) produced a similar degree of inhibition, irrespective of whether nicotine or an equipotent concentration of acetylcholine was used to evoke IACh. NPY(16–36) failed to alter voltage-dependent inward or outward currents. Intracellular cAMP, and extracellular dibutyryl-cAMP, produced a slowly developing increase in IACh. Intracellular cAMP, extracellular 8-Br-cAMP or dibutyryl-cAMP, and an inhibitor of cyclic nucleotide phosphodiesterases 3-isobutyl-l-methylxanthine (IBMX), decreased the inhibitory effect of NPY(16–36) on lACh. Although the intracellular application of the cAMP-dependent protein kinase A inhibitor [PKI(14–24)amide] alone did not alter IACh, it potentiated the effect of NPY(16–36) in interaction experiments. While the NPY(16–36)-induced inhibition of IACh was reversed on washout of the peptide, the slightly shorter C-terminal fragment NPY(18–36) caused a long-lasting depression of both IAch and catecholamine secretion evoked by nicotine. This depression was smaller in the presence of extracellular 8-Br-cAMP than in its absence. NPY(18–36) did not alter the secretory activity induced by a high concentration of potassium. It appears that, by activating Y3-receptors, NPY inhibits nAChR-current and the resulting secretion of catecholamines from bovine chromaffin cells. This process may involve a G protein-mediated decrease in intracellular cAMP with a subsequent decrease in the degree of phosphorylation of the nAChR-channel.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: Key words Neuropeptide Y ; Catecholamines ; Cyclic adenosine monophosphate ; Chromaffin cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of neuropeptide Y [NPY(1–36)] and related peptides on the voltage-dependent currents and the nicotinic acetylcholine receptor (nAChR) currents (IACh) of bovine adrenal chromaffin cells was investigated using the whole-cell patch clamp technique. Catecholamine release from single chromaffin cells was measured by means of fast cyclic voltammetry. The potency order of these peptides in inhibiting IACh evoked by nicotine was NPY(1–36), NPY (16–36)〉peptide YY(PYY)〉[Leu31, Pro34]NPY. NPY(16–36) produced a similar degree of inhibition, irrespective of whether nicotine or an equipotent concentration of acetylcholine was used to evoke IACh. NPY(16–36) failed to alter voltage-dependent inward or outward currents. Intracellular cAMP, and extracellular dibutyryl-cAMP, produced a slowly developing increase in IACh. Intracellular cAMP, extracellular 8-Br-cAMP or dibutyryl-cAMP, and an inhibitor of cyclic nucleotide phosphodiesterases 3-isobutyl-1-methyl-xanthine (IBMX), decreased the inhibitory effect of NPY(16–36) on IACh. Although the intracellular application of the cAMP-dependent protein kinase A inhibitor [PKI(14–24)amide] alone did not alter IACh, it potentiated the effect of NPY(16–36) in interaction experiments. While the NPY(16–36)-induced inhibition of IACh was reversed on washout of the peptide, the slightly shorter C-terminal fragment NPY(18–36) caused a long-lasting depression of both IACh and catecholamine secretion evoked by nicotine. This depression was smaller in the presence of extracellular 8-Br-cAMP than in its absence. NPY(18–36) did not alter the secretory activity induced by a high concentration of potassium. It appears that, by activating Y3-receptors, NPY inhibits nAChR-current and the resulting secretion of catecholamines from bovine chromaffin cells. This process may involve a G protein-mediated decrease in intracellular cAMP with a subsequent decrease in the degree of phosphorylation of the nAChR-channel.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5060
    Keywords: Avena sativa ; oats ; selection ; independent culling ; harvest index ; vegetative growth index ; unit straw weight ; biological yield ; growth rate ; heritability ; genotypic correlatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Most variation in grain yield of oats is due to variation in harvest index and vegetative growth index, but the latter traits are negatively associated. Therefore we used independent culling levels to select oat genotypes with high levels of vigor traits and a desirable level of harvest index in an attempts to maximize grain yield. Harvest index and vegetative growth index or harvest index and unit straw weight were selected at various culling levels. Intensive selection for harvest index resulted in high harvest index but no grain yield improvement, because the selected lines had poor vigor. Intensive selection for vegetative growth index or unit straw weight resulted in high biomass but low harvest index. The most effective combination of culling levels was to select 25% of the original population for harvest index and, subsequently, to select for vegetative growth index or unit straw weight at an 8% intensity in the remnant population.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5060
    Keywords: Avena sativa ; oats ; Avena sterilis ; interspecific cross ; growth rate ; straw yield ; grain yield ; heading date ; harvest index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Improved grain yields in lines of oats from matings of Avena sativa x A. sterilis were found to be due to increased plant growth rate. Growth rates of oats were quantitatively inherited, with the minimum number of effective factor pairs segregating in the interspecific matings ranging from 3 to 9. Heritability values for this trait averaged 0.4. Growth rate was highly and positively correlated with bundle weight, straw yield, grain yield, and unit straw weight, but it was uncorrelated with heading date and harvest index. Correlations with plant height were low. Thus, it should be possible for oat breeders to combine the high growth rates from A. sterilis with any combination of agronomic traits.
    Type of Medium: Electronic Resource
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