SUPPRESSION OF NEURONAL POTASSIUM A-CURRENT BY ARACHIDONIC-ACID

The effect of arachidonic acid on the A current (I-A) has been studied in dissociated bullfrog neurons under whole-cell voltage-clamp conditions. Arachidonic acid reduced I-A in a dose-dependent and reversible manner without a shift in the prepulse inactivation voltage-current relation. 1.75 mu M inhibited I-A by 50%, and higher concentrations caused a total suppression. In addition, arachidonic acid increased the M-current (I-M), a different potassium current that does not inactivate. Neither indomethacin nor nordihydroguaiaretic acid, cyclooxygenase and lipoxygenase inhibitors respectively, prevented I-A reduction. In contrast, nordihydroguaiaretic acid prevented I-M enhancement. Eicosatetraynoic acid, an arachidonic acid analog that cannot be metabolized, also reduced I-A. These results suggest that arachidonic acid metabolism is not required to suppress I-A.