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  • 1
    Electronic Resource
    Electronic Resource
    Nucleotide regulation of a calcium-activated cation channel in the rat insulinoma cell line, CRI-G1 (1994)
    Springer
    The journal of membrane biology 141 (1994), S. 101-112 
    Details
    ISSN: 1432-1424
    Keywords: Rat insulinoma cell line ; CRI-G1 ; Nucleotide regulation ; Calcium-activated nonselective cation channel ; Patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The nucleotide regulation of a calcium-activated nonselective cation (Ca-NS+) channel has been investigated in the rat insulinoma cell line CRI-G1. The activity of the channel is reduced by both AMP and ADP (1–100 μm) in a concentration-dependent manner, with AMP being more potent than ADP. At lower concentrations (0.1–5 μm), both ADP and AMP activate the channel in some patches. Examination of the nucleotide specificity of channel inhibition indicates a high selectivity for AMP over the other nucleotides tested with a rank order of potency of AMP 〉 UMP 〉 CMP ≥GMP. Cyclic nucleotides also modulate channel activity in a complex, concentration-dependent way. Cyclic AMP exhibits a dual effect, predominantly increasing channel activity at low concentrations (0.1–10 μm) and reducing it at higher concentrations (100 μm and 1 mm). Specificity studies indicate that the cyclic nucleotide site mediating inhibition of channel activity exhibits a strong preference for cyclic AMP over cyclic GMP, with cyclic UMP being almost equipotent with cyclic AMP. Cyclic IMP and cyclic CMP are not active at this site. The cyclic nucleotide site mediating activation of the channel shows much less nucleotide specificity than the inhibitory site, with cyclic AMP, cyclic GMP and cyclic IMP being almost equally active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238244
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of pyridine nucleotides on the activity of a calcium-activated nonselective cation channel in the rat insulinoma cell line, CRI-G1 (1994)
    Springer
    The journal of membrane biology 142 (1994), S. 299-307 
    Details
    ISSN: 1432-1424
    Keywords: Calcium-activated nonselective channel ; Rat insulinoma cell line ; CRI-G1 ; Pyridine nucleotides β-NAD+-NS+ channel ; Nucleotide regulation ; AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The activity of a calcium-activated nonselective (Ca-NS+) channel in a rat insulinoma cell line (CRI-G1) is inhibited by pyridine nucleotides in excised patches. The effects of all four pyridine nucleotides tested, β-NAD+, β-NADH, β-NADP+ and β-NADPH were very similar when tested at 0.1 mm, and at 1 mm the phosphorylated forms, β-NADP+ and β-NADPH, appeared to be slightly more potent than β-NAD+ and β-NADH. All the pyridine nucleotides tested reduced both the open state probability of the channel and the number of functional channels observed in a single patch. The application of β-NAD+, but not of the other nucleotides tested, to the cytoplasmic surface of isolated inside-out patches from CRI-G1 cells opened a novel nonselective cation channel (the β-NAD+-NS+ channel). The activity of this new channel is calcium sensitive and may also be inhibited by AMP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233437
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  • 3
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    Dietary nucleotides prevent decrease in cellular immunity in ground-based microgravity analog (2002)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Microgravity and stress of spaceflights result in immune dysfunction. The role of nutrition, especially nucleotide supplementation, has become an area of intensive research and significant interest in immunomodulation for maintenance of cellular immune responses. The studies presented here evaluate the plausibility of administering nucleotides to obviate immune dysfunction in an Earth-based in vivo analog of microgravity as studied in anti-orthostatic tail suspension (AOS) of mice. Mice were divided into three housing groups: group, isolation, and AOS. Mice were fed either control chow diet (CD), or RNA-, adenine-, or uracil-supplemented CD for the 1-wk duration of the experiments. In AOS mice, supplemental nucleotides significantly increased in vivo lymph node proliferation and ex vivo lymphoproliferation response to alloantigen and mitogens, respectively, and interleukin-2 and interferon-gamma production. A lower corticosterone level was observed in uracil-supplemented CD compared with CD. These results suggest that exogenous nucleotide supplementation, especially uracil, of normal diet is beneficial in the maintenance and restoration of the immune response during the microgravity analog conditions.
    Keywords: Aerospace Medicine
    Type: Journal of applied physiology (Bethesda, Md. : 1985) (ISSN 8750-7587); Volume 93; 1; 161-6
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Endogenous circulating sympatholytic factor in orthostatic intolerance (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Sympathotonic orthostatic hypotension (SOH) is an idiopathic syndrome characterized by tachycardia, hypotension, elevated plasma norepinephrine, and symptoms of orthostatic intolerance provoked by assumption of an upright posture. We studied a woman with severe progressive SOH with blood pressure unresponsive to the pressor effects of alpha(1)-adrenergic receptor (AR) agonists. We tested the hypothesis that a circulating factor in this patient interferes with vascular adrenergic neurotransmission. Preincubation of porcine pulmonary artery vessel rings with patient plasma produced a dose-dependent inhibition of vasoconstriction to phenylephrine in vitro, abolished vasoconstriction to direct electrical stimulation, and had no effect on nonadrenergic vasoconstrictive stimuli (endothelin-1), PGF-2alpha (or KCl). Preincubation of vessels with control plasma was devoid of these effects. SOH plasma inhibited the binding of an alpha(1)-selective antagonist radioligand ([(125)I]HEAT) to membrane fractions derived from porcine pulmonary artery vessel rings, rat liver, and cell lines selectively overexpressing human ARs of the alpha(1B) subtype but not other AR subtypes (alpha(1A) and alpha(1D)). We conclude that a factor in SOH plasma can selectively and irreversibly inhibit adrenergic ligand binding to alpha(1B) ARs. We propose that this factor contributes to a novel pathogenesis for SOH in this patient. This patient's syndrome represents a new disease entity, and her plasma may provide a unique tool for probing the selective functions of alpha(1)-ARs.
    Keywords: Aerospace Medicine
    Type: Hypertension (ISSN 0194-911X); 36; 4; 553-60
    Format: text
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    NASA TECHNICAL REPORTS
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