[Using serial tachograms to measure the evoked impulse activity of isolated hippocampal neurons].

In these studies, we investigated the phenomenon of change in impulse activity of isolated hippocampal neurons during longtime recording. We described the use of serial tachograms during registering the electrical activity of neurons, analysis of which can improve the reliability of data. An analysis of the data identified three phases of changes in impulse activity of isolated neurons in the experimental registrations: a phase of increased activity, phase of stable activity and the phase of declining activity. It is established that in conditions of the perforated patch-clamp the phase of stable activity started at 10-15 minutes after formation of the tight junction and had an average duration of 30 minutes. It is shown that the use of the serial tahograms and phases of activity improves the quality of assessment in the measurement of the electrical activity of neurons.

[The action of pilocarpine on the accommodation properties of isolated phasic neurons of the rat hippocampus]. / Vyvchennia diï pilokarpinu na vlastyvosti akomodatsiï izol'ovanykh faznykh neironiv hipokampa shchura.

Using of voltage and current clamp methods in conditions of perforated membrane fragment, we investigated the accommodation properties of isolated neurones from different zones of hippocampus. The investigated neurones could be separated into two main groups concerning their responses to prolonged pulses of suprathreshold depolarization--neurones which after generation of several action potentials (AP) stopped their generation (phasic, F-neurones), and (tonic, T-neurones), which did not accommodate and continued AP generation during entire depolarizing pulse. Comparison of ionic current composition in neurones of both groups has shown, that T-neurones demonstrate more expressed inactivation of outward currents that can be due to the presence of a fast inactivating A-type potassium current, or decreased inactivation of inward currents. Pilocarpine, well-known epileptogenic compound increased accommodation and induced significant slow-down of outward current inactivation in F- neurones. It can be suggested that the presence of A-type potassium current and/or a slowly inactivating component of inward current can play main role in determining the accommodation effect in hippocampal neurones.