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  • 1
    Electronic Resource
    Electronic Resource
    Prevention of Monensin-Induced Hyperpolarization in NG108-15 Cells (2000)
    Springer
    Neurochemical research 25 (2000), S. 941-948 
    Details
    ISSN: 1573-6903
    Keywords: Action potential ; chlorpromazine ; In vitro model ; membrane potential ; NG108-15 (neuroblastoma X glioma) hybrid cells ; monensin ; ouabain ; quinine ; verapamil ; trifluoperazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The NG108-15 (neuroblastoma X glioma hybrid) cell line was used as an in vitro neuronal model to evaluate potential antagonists of the Na+-selective carboxylic ionophore monensin. Changes in membrane electrical characteristics induced by monensin with and without the simultaneous administration of antagonists were measured using intracellular microelectrode techniques. Bath application of monensin (3 μM) produced a hyperpolarization of ≃ 35 mV. Monensin also altered the generation of action potentials in response to electrical stimulation in 14 of 24 (58%) exposed cells, as evident in a partial or complete loss of action potentials or in an alteration of action potential waveform. The antagonists used were Na+-K+ pump inhibitor ouabain (1–3 μM), the Ca2+-dependent K+ channel blocker quinine (3–30 μM) or drugs known to influence Ca2+ signaling in cells, i.e., trifluoperazine (3–10 μM), verapamil (1–10 μM) or chlorpromazine (3–30 μM). On a molar basis, ouabain was the most and trifluoperazine the least effective of the antagonists. Quinine, verapamil and chlorpromazine all prevented the development of the hyperpolarization in an approximate concentration-dependent manner. However, none of these drugs was able to block the effects of monensin on action potentials. Indeed, high concentrations of the antagonists that were most effective in preventing the hyperpolarization accentuated impairments in action potential generation and also reduced input resistance in many cells. Thus, none of these antagonists appears suitable for transition to in vivo antidotal protection studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007548307554
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of Protonophores on Membrane Electrical Characteristics in NG108-15 Cells (2000)
    Springer
    Neurochemical research 25 (2000), S. 263-268 
    Details
    ISSN: 1573-6903
    Keywords: Action potential ; CCCP ; FCCP ; In vitro model ; membrane potential ; membrane resistance ; NG108-15 (neuroblastoma X glioma) hybrid cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies were conducted to determine the effects of bath application of the protonophores carbonyl cyanide m-chlorophenylhydrazone (CCCP) and carbonyl cyanide p-(trifluoromethoxy)-phenylhydrazone (FCCP) on membrane electrical characteristics of differentiated NG108-15 (neuroblastoma X glioma hybrid) cells. Membrane resting potential (Vm), input resistance (Rin) and electrically induced action potential generation were measured using intracellular micro-electrode techniques. Both compounds produced concentration-dependent depolarization rather than the hyperpolarization commonly found with other central mammalian neurons. CCCP and FCCP also reduced Rin and disrupted the generation of action potentials in a concentration-dependent manner. The contribution of the observed alterations to the in vivo toxicity of these compounds remains to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007531822068
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Scanning cytophotometric analysis of myocardial nucleic acid and chromatin changes in soman toxicated rabbits (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 2 (1984), S. 237-242 
    Details
    ISSN: 0263-6484
    Keywords: Heart ; Feulgen-DNA ; Azure B-RNA ; microdensitometry ; soman toxicity ; cardiac muscle ; cytochemistry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Myocardial nucleic acid responses were analysed in New Zealand White rabbits 20 min-1 h and 6-8 h following single subcutaneous injections of soman (20, 30, or 40 μg kg-1). Scanning-integrating microdensitometry was used to quantify Azure B-RNA and Feulgen-DNA (F-DNA) levels, and changes in the suseptibility of chromatin to Feulgen acid hydrolysis (F-DNA reactivity) of individual ventricular myocardial cells. With a dosage of 20 μg kg-1 soman, no RNA alterations were evidenced at 1 h whereas at 6-8 h myocardial cells exhibited higher RNA levels and an increase in F-DNA reactivity of chromatin. With dosages of 30 and 40 μg kg-1 soman there was an augmentation in RNA levels and in the acid hydrolysability of nuclear chromatin at both 20 min-1 h and 6-8 h. It is postulated that the observed cellular transformations represent a compensatory augmentation in myocardial metabolic functioning presumably in response to an increased functional demand on the ventricular myocardium. The absence of cytopathic or cytochemical evidence of impairment in nucleic acid metabolism is inconsistent with the premise that soman exerts direct cytotoxic effects on rabbit myocardium.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290020410
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative cytochemical analyses of ovarian luteal and interstitial cell RNA in relation to plasma progestins during pseudopregnancy in the rat (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 1 (1983), S. 173-178 
    Details
    ISSN: 0263-6484
    Keywords: RNA ; quantitative cytophotometry ; luteal regression ; ovarian 20α-hydroxypregn-4-ene-3-one ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Luteal and interstial cell RNA contents and circulating progesterone (P) and 20α-hydroxypregn-4-ene-3-one (20α-OH P) levels were measured during pseudopregnancy in order to characterize relationships between ovarian 20α-OH P secretion and luteal regression. Functional luteolysis, as manifested in depressed P levels, was not associated with concurrent elevations in 20α-OH P. Rather, augmented 20α-OH P levels were evidenced in periovulatory periods at the onset and termination of pseudopregnancy, subsequent to RNA accumulation in both luteal and interstitial compartments. It is postulated that 20α-OH P, the putative inactive metabolite of P, is produced by both ovarian compartments in a cyclic manner and in response to gonadotrophin released in the preovulatory period.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290010310
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    Paper (German National Licenses)
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