[Short and long latent effects of 15-hydroxyeicosatetraenoic acid on the extinction of the acetylcholine-induced inward current in neurons of the Helix lucorum]

The impact of a non-cyclized arachidonic acid derivative 15S-hydroxy-5Z, 8Z, 11Z, 13E-eicosatetraenoic acid (15-HETE) upon the dynamics of the inward current extinction, caused by repeated ion-tophoretic acetylcholine applications on the soma, was studied through a double electrode voltage clamp technique on the Helix lucorum identified neurons RPa3 and LPa3. The extracellular effect of 15-HETE (4-16 microM) was found to have a two phase influence on the inward current extinction, depending on the time of exposure to the compound. The short-latent effect (up to 60-80 min) displays itself as an extinction decrease, whereas the long-latent effect (after 60-80 min) - as an enhanced extinction. The effects caused by 15-HETE are irreversible. The short-latent one was probably due to the earlier described inhibition of 5- and 12-lipoxygenase enzymes by 15-HETE while the long-latent one - due to its intrinsic function.