Effects of (±)-kavain on inactivation of voltage-operated Na+ channels

Autor: E. I. Magura
Rok vydání: 1996
Předmět:
Zdroj: Neurophysiology. 28:173-177
ISSN: 1573-9007
0090-2977
DOI: 10.1007/bf02262780
Popis: Effects of a kava-pyrone (±)-kavain on fast inactivation of Na+ channels were studied in experiments on isolated neurons from the rat hippocampus. (±)-Kavain was found to block Na+ channels, and its effect was voltage-dependent. At the holding potentials of −100 and −80 mV, IC50 for (±)-kavain was 744.9 and 178.8 µM, respectively. The inactivation characteristic of Na+ channels was satisfactorily described with the Boltzmann's equation both in the control and under (±)-kavain application. (±)-Kavain at a 330 µM concentration shifted theV1/2 toward more negative values by 14.4 mV and concurrently modified the slope factor: the latter was 5.7 mV in the control, while under the influence of 330 µM (±)-kavain it reached 6.7 mV. In agreement with Hille's hypothesis of a “modulated receptor,” inactivated Na+ channels demonstrated an increased sensitivity to kavain. (±)-Kavain effects resulted in an increase in the rate of depolarization-related fast inactivation, while the process of recovery from inactivation became slower when the membrane was hyperpolarized. Our data show that under the (±)-kavain effect the probability of the inactivated state of Na+ channels increases, and the state of fast inactivation is stabilized.
Databáze: OpenAIRE
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