[Apoptosis in the nervous system].

Apoptosis (from Greek apoptosis, i.e., falling of leaves) is the phenomenon of programmed cell death, which plays an important role in the normal embryonic development and maintenance of homeostasis of the differentiated tissues of adult organisms.

The effect of carbachol and alpha-bungarotoxin on the frequency of miniature endplate potentials at the frog neuromuscular junction.

The effects of an acetylcholine analogue, carbachol (CCh), and a purified irreversible nicotinic antagonist, -bungarotoxin (BTX), on the frequency of the miniature endplate potentials (mEPPs) at the neuromuscular junction of the frog were tested at 20 and 10 C. CCh (5 10-6 m) reduced the frequency of mEPPs to about 60 %; this reduction was not affected by 1 10-7 g ml-1 BTX. BTX also reversibly decreased the mEPP frequency by 40 %, but not in the presence of CCh or in Ringer solution with 0 or 8 mM Ca2+.

Cyclic AMP synchronizes evoked quantal release at frog neuromuscular junctions.

At frog neuromuscular junction, noradrenaline (NA) shortens the release period for evoked quantal release acting on a beta1 receptor. To test the hypothesis that this action of NA is mediated by cAMP, we measured the latencies of focally recorded uni-quantal endplate currents (EPCs) after application of dibutyryl-cAMP (db-cAMP) and adenylyl cyclase activator, forskolin. The interval between the time when responses with minimal delay appeared and the point at which 90% of all latencies had occurred (P90 parameter) was shortened in the presence of both 1 x 10(-6) mol/l db-cAMP and 1 x 10(-6) mol/l forskolin by about 30%.

[The "direct mitogen" lead nitrate causes an intensification in lipid peroxidation and Ito cell activation in the rat liver].

We have used biochemical and immunohistochemical methods to study lipid peroxidation and activation of Ito cells in rat liver after a single administration of lead nitrate, a "direct mitogen". Lead nitrate was shown to injure hepatocytes through an increased lipid peroxidation. Response to the injury included increase in the proliferative activity of parenchymal and sinusoidal liver cells.

[Effect of sodium nitroprusside on the mediator release and functional properties of the postsynaptic membrane at the neuromuscular junction].

The effect of nitric oxide donor sodium nitroprusside on the end-plate currents was studied under two-electrode voltage-clamp condition at frog neuro-muscular junction. Sodium nitroprusside (10(-4) M) reduced to the half the amplitude of end-plate currents while did not change miniature end-plate currents indicating the presynaptic nature of end-plate depression. In keeping with such suggestion sodium nitroprusside essentially (to 33%) suppressed the frequency of miniature end-plate currents but did not affect the decay time constant and voltage-dependence of miniature end-plate decay.

[Contact inhibition of desmin expression in rat liver Ito cells in vitro].

The presence of desmin is used to identify the Ito cells in rat liver and to evaluate the purity of separated and cultured cells. The present study was conducted to evaluate the expression of cytoskeletal (with special emphasis on desmin) and intercellular matrix proteins in cultured rat liver Ito cells. The Ito cells were isolated by enzymatic digestion of rat liver and purified by single-step Nycodenz gradient.

[GABA--the basic mediator of excitation in the early stages of hippocampal development].

GABA is the principal neurotransmitter of inhibition in the adult mammalian brain. However, at early stages of development, including embryonic period and first week of postnatal life, GABA plays the role of main neurotransmitter of excitation. The paradoxical excitatory effect of GABA is due to an inversed chloride gradient and therefore a depolarizing direction of GABA-A receptor mediated responses.

Desensitization shortens the high-quantal-content endplate current time course in frog muscle with intact cholinesterase.

1. The desensitization induced by bath-applied carbachol or acetylcholine (ACh) and potentiated by proadifen (SKF 525A) was studied in the frog sartorius with intact synaptic acetylcholinesterase (AChE). 2.

Non-quantal acetylcholine release in the mouse diaphragm after phrenic nerve crush and during recovery.

The progressive decline and recovery of spontaneous quantal acetylcholine (ACh) release (miniature endplate potentials, MEPPs) and the H-effect were measured in the mouse diaphragm after nerve crush and during regeneration. The H-effect is the hyperpolarization of the muscle fibre membrane produced by the addition of (+)tubocurarine, which indicates non-quantal ACh release. One hour after nerve crush the H-effect had declined to 50% of control values and 4 h later the H-effect disappeared completely.

Neuroimmunological aspects of fetus and newborn brain damage in complicated pregnancy.

Problem: The role of neuroautoimmune mechanisms in pathogenesis of perinatal damage of fetus and neonate brain during complicated pregnancy is considered to be important.

Method: To determine neurospecific antigens (NSA) and their antibodies, ELISA and two-site column enzyme immunoassay were used.

Results: The contents of NSA and anti-brain antibodies, associated with fetal brain congenital development defects, account for the development of neuroautoimmune shifts in the mother-fetus system.

Electromyography data on spontaneously hypertensive rats.

1. To investigate the state of nerve-muscle excitability in 20 spontaneously hypertensive rats and 22 Wistar rats local electromyography was carried out in periods of rest and under the maximum strain of 10 min ischaemia of m.flexor femoris (Trusso's test).

Muscle NMDA receptors regulate the resting membrane potential through NO-synthase.

The early postdenervation depolarization of rat diaphragm muscle fibres (8-10 mV) is substantially smaller (3 mV) when muscle strips are bathed with 1 mM L-glutamate (GLU) or N-methyl-D-aspartate (NMDA). The effects of GLU and NMDA are not seen in the presence of aminophosphonovaleric acid (APV), a blocker of NMDA-subtype of glutamate receptors, 5 mM Mg2+ (which blocks NMDA-controlled ion channels) and L-nitroarginine methylester (NAME), an inhibitor of NO-synthase. This indicates that NMDA-subtype of GLU receptors might be involved in the regulation of the membrane potential in muscle fibres, most probably through the NO-synthase system.

Modelling endplate currents: dependence on quantum secretion probability and decay of miniature current.

Quantification of the time course and amplitude of endplate currents (EPC) was made with respect to dispersion of quanta secretion and to changes in the exponential decay of miniature endplate currents (tau mepc). The relationship between RPC amplitude and tau mepc follows a double-exponential curve with tau1 = 0.3 ms and tau2 = 6 ms.

The effect of acetylcholine and related drugs on currents at the frog motor nerve terminal.

Acetylcholine, acetylthiocholine, carbachol, suberyldicholine, propionylcholine, succinylcholine, methylfurmethide and F 2268 were tested on motor nerve ending currents recorded with an extracellular microelectrode. The isolated and transversally cut cutaneous pectoris muscle of frog Rana ridibunda was used. Only acetylcholine and acetylthiocholine affected the spike waveforms in a concentration-dependent manner.