[Changes in the indices of neuronal functional activity under the action of piracetam as a possible basis for realizing the effects of nootropic agents].

Effects of piracetam (PA, 4-20 mM) on some electric characteristics of neuron activity were studied in vitro in identified neurons of Lymnaea stagnalis. Stimulation, single-electrode voltage clamping and recording of activity of the neuron were realized via the same intracellular microelectrode. PA-induced alterations of the characteristics under study were observed in 60-70% of recorded neurons. Modifications of action potential generation threshold, of the slope and shape of steady-state membrane current-voltage characteristics and appearance of PA-induced transmembrane ion currents occurred more frequently than changes in other parameters. Typically, Ca channel blockers (nifedipine and Cd ions) reversed or reduced the influence of PA on the studied characteristics of tested cell activity, i. e., acted as PA antagonists. This suggests that realization of observed PA effects is due to its action on Ca channel functioning. Selective modification of the latter can determine development of various PA effects at the cellular level. An assumption is discussed that piracetam, being a highly efficient cellular adaptogen and modifying specifically Ca channels of cells, is capable of moving them to a new level of functioning which is necessary for ensuring complex forms of nervous activity.