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  • 1
    Electronic Resource
    Electronic Resource
    Use of the cell-attached patch clamp technique to examine regulation of single cardiac K channels by cyclic GMP (1989)
    Springer
    Molecular and cellular biochemistry 80 (1989), S. 27-35 
    Details
    ISSN: 1573-4919
    Keywords: cyclic GMP ; K channels ; cardiac electrophysiology ; muscarinic agonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Cyclic nucleotides play a central role in the modulation of ion channels in a variety of tissues, including the heart. In order to determine the possible role of cyclic GMP (cGMP) in the regulation of the background K channel activity of cardiac cells, the effect of 8-Br-cGMP on the inwardly-rectifying K channels of cultured ventricular myocytes from embryonic chick hearts was examined. 8-Br-cGMP (10-4 to 10-3 M) inhibited these single channel currents within 3 to 10 min. Spontaneous recovery of the currents occurred with prolonged (≥ 15 min) exposure to 8-Br-cGMP, but this recovery was accompanied by altered channel behavior. Thus, a new long-lasting open state of the channel appeared, in addition to the open state observed prior to 8-Br-cGMP addition. Superfusion of the cells with the muscarinic agonist carbamylcholine (10-5 M) also resulted in inhibition of the currents, which suggests that the cGMP-mediated inhibition of these channels may occur under physiological conditions. Thus, it appears that cGMP may be an important modulator of the background K conductance (and excitability) of cardiac cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231001
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of platelet-activating factor on single potassium channel currents in guinea pig ventricular myocytes (1990)
    Springer
    Molecular and cellular biochemistry 93 (1990), S. 69-76 
    Details
    ISSN: 1573-4919
    Keywords: platelet-activating factor ; potassium channels ; cardiac electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Platelet-activating factor (PAF) has been implicated as one of the mediators of cardiac anaphylaxis. This phospholipid has been shown to have numerous effects on a variety of tissues, including the heart. Among these effects are alterations in the resting potential and generation of arrhythmias at very low concentrations. This suggests that PAF may modulate the activity of the background, inwardly-rectifying potassium current (IK1). Thus, the effects of PAF on IK1 were examined at the single channel level. Ventricular cells were isolated from adult guinea pig hearts and single channel currents recorded from cell-attached patches. PAF had substantial effects on the single channel currents at sub-nanomolar concentrations (10−11 to 10−10 M). PAF initially caused flickering of the channels, followed by a gradual prolonged depression of channel activity. Since these potassium channels play a major role in determining the resting potential and excitability of the cardiac cell, the effects of PAF on IK1 may play a major role in the deleterious electrophysiological actions of PAF on the heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223494
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of chemicals from earthworms and fish that elicit prey attack by ingestively naive garter snakes (Thamnophis) (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 67-77 
    Details
    ISSN: 1573-1561
    Keywords: Chemoreception ; garter snakes ; Thamnophis sirtalis ; chemical cues ; Lumbricus terrestris ; earthworm ; Pimephales promelas ; fish ; prey odors ; glycopeptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Materials previously shown to elicit increased tongue-flicking and prey attack in garter snakes (Thamnophis sirtalis) were isolated from both earthworms (Lumbricus terrestris) and fish (Pimephales promelas). Both high- and low-molecular-weight components from earthworms and fish stimulated attacks and increased tongue-flicking in previously unfed neonate garter snakes relative to distilled water controls. Earthworm collagen was also effective, but even concentrated fractions were less effective than raw extract. Conflicting reports on the effectiveness of collagen suggest that the salient chemical(s) is a smaller molecule tightly bound to collagen and resisting standard purification methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021268
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A comparative analysis of scoring methods for chemical discrimination of prey by squamate reptiles (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 45-65 
    Details
    ISSN: 1573-1561
    Keywords: Reptilia ; tongue-flicks ; broad-headed skink ; Eumeces laticeps ; garter snake ; Thamnophis sirtalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In studies of squamate responses to prey chemicals presented on cotton-tipped applicators, investigators typically record several responses, each of which gives only part of the overall picture. The tongue-flick/attack score (TFAS) is a widely used composite measure of response strength that accounts for attack, its latency, and number of tongue-flicks. We present data and analyses on these variables and investigate the utility of several other possible response variables. It is concluded, for both practical and theoretical reasons, that TFAS and two modifications of it are the best measures of response strength. Uses and statistical analyses of TFAS and variables derived from it are discussed. It is recommended that information on tongue-flick rate, number of individuals attacking, and latency to attack be presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021267
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of earthworm- and fish-derived chemicals eliciting prey attack by garter snakes (Thamnophis) (1988)
    Springer
    Journal of chemical ecology 14 (1988), S. 855-881 
    Details
    ISSN: 1573-1561
    Keywords: Chemoreception ; garter snakes ; Thamnophis sirtalis ; chemical cues ; vomeronasal system ; Lumbricus terrestris ; Pitnephales promelas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Materials eliciting increased tongue flicking and prey attack in garter snakes were isolated from both earthworm and fish prey. New extraction methods based on chloroform-methanol mixtures are valuable adjuncts to the more typical aqueous preparations. Both high- and low-molecular weight components from earthworms and fish were active. The similarity between the active chemicals in these two classes of prey was established using several methods of analysis. These included chromatography, carbohydrate and amino acid analyses, and nuclear magnetic resonance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01018779
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    Paper (German National Licenses)
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