HALOPERIDOL MODULATES IONIC TRANSPORT OF CHARA CORALLINA CELLS

The effect of the haloperidol (HP), a dopamine D2-receptor antagonist on the function of ionic channels of the electrically excitable plasma membrane and on the cytoskeleton of Chara corallina cells was investigated. Haloperidol was shown to block plasmalemmal Ca2+ channels. Apart from Ca2+ current reduction, the presence of HP slowed the kinetics of both activation and inactivation of ionic channels. The influence of haloperidol on the membrane structure was reversible. After removal of the neuromodulator, both the amplitude and the kinetics of the current development were seen to be completely restored. HP had no effect on Ca2+-activated chloride channels. Haloperidol inhibited cytoplasmic motion related to microfilamentary complex. Once haloperidol was removed from cell washing solution, cytoplasmic motion was restored. These results let us to assume that in the presence of HP the concentration of free Ca2+ in cytoplasm increases. Also it can be assumed that plasmalemmal Ca2+-channels of Ch. corallina cells contain binding sites similar to dopamine receptors and their antagonists.