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The depressant action of flurazepam on the maximum rate of rise of action potentials recorded from guinea-pig papillary muscles

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Summary

  1. 1.

    In isolated papillary muscles of guinea-pigs the effect of flurazepam monohydrochloride on transmembrane resting and action potentials was studied using the microelectrode recording technique.

  2. 2.

    Flurazepam monohydrochloride (2.5×10−5 to 2×10−4 M) prolonged the duration of the action potential, decreased its amplitude and its maximum rate of rise, and left the resting potential unchanged. The decrease in the maximum rate of rise was a function of the concentration used and also depended strongly on the rate of stimulation.

  3. 3.

    Similar to quinidine and many quinidine-like antifibrillatory drugs, the depressed maximum rate of rise recovered in spite of the presence of flurazepam whenever the stimulation of the preparation was interrupted for a sufficient period of time.

  4. 4.

    The times required for recovery were comparatively short (about 20 sec) and the values for the maximum extent of recovery were less with flurazepam than those reported for several quinidine-like drugs.

  5. 5.

    The experimental data suggest that flurazepam blocks the rapid sodium inward current. The kinetics of blocking of this current by flurazepam and the kinetics of recovery during a pause in stimulation are discussed.

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Author notes

  1. G. Liebeswar

    Present address: Department of Neurobiology and Behavior, New York University Medical Center and The Public Health Research Institute of the City of New York, New York, USA

Authors and Affiliations

  1. Institute of Pharmacology, University of Vienna, Vienna, Austria

    G. Liebeswar

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  1. G. Liebeswar
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Additional information

A preliminary report was given at the 12th Spring Meeting of the German Pharmacological Society in Mainz, 1971.

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Liebeswar, G. The depressant action of flurazepam on the maximum rate of rise of action potentials recorded from guinea-pig papillary muscles. Naunyn-Schmiedeberg's Arch. Pharmacol. 275, 445–456 (1972). https://doi.org/10.1007/BF00501132

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  • DOI: https://doi.org/10.1007/BF00501132

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