[Use of biological methods in the analysis of the purinergic activity of etimizol]. / Ispol'zovanie biologicheskikh metodov dlia analiza purinergicheskoi aktivnosti étimizola.

To analyse etimizol purinergic activity, methods of biological analysis were applied using isolated smooth muscle strips of the guinea-pig caecum and developing embryo cultures of the sea urchin (Strongylocentrotus intermedius). Stimulating etimizol action in 10(-8)-10(-12) M concentration was observed on embryonal development in the sea urchin to be eliminated by co-action of etimizol and P1-purinoceptor antagonist theophylline. The analogous action of the preparations was established using isolated smooth muscle strips of the guinea-pig caecum.

[Action of enkephalins on synaptic processes in the metasympathetic nervous system]. / Issledovanie deistviia énkefalinov na sinapticheskie protsessy v metasimpaticheskoi nervnoi sisteme.

Experimental data were obtained on the effect of leu- and metenkephalin solutions (0.01-10.0 micrograms) on spontaneous responses and those evoked by transmural stimulation of the neural structures in the neuro-muscular preparation which included the myenteric plexus and circular smooth muscle layer. The observed excitatory action of enkephalins involving depolarization of the smooth muscle cell membrane, the increase of spontaneous AP frequency, reduced amplitude of the evoked ISP, increased voltage and intensified contractile activity of the preparation are related to participation of the opiate receptors. (Naloxone administration abolished the enkephalin effects). Application of alpha- and beta-adrenergic blocking drugs failed to change the type of their action. Enkephalin effects were most pronounced at low frequency stimulation and were not observed in the solution containing both M- and N-cholinergic blocking drugs. Enkephalins seem to participate in the mechanisms of descending tonic control of the smooth muscle activity maintained by non-adrenergic, non-cholinergic motor neurons.

[Responses of enterometasympathetic neurons to transmural electric stimulation]. / Reaktsii enterometasimpaticheskikh neironov na transmural'noe élektricheskoe razdrazhenie.

Transmural electrical stimulation evokes a multicomponent response in the enterometasympathetic ganglion, the response consisting of early low-amplitude APs and late single AP or bursts of APs. Some of the neurons developed a high-amplitude antidromic spike following the stimulation. Application of ganglio-blocking agent hexonium (10(-6) g/ml), solutions with high magnesium concentration (up to 10 mM) and high-frequency stimulation (30 Hz) led to disappearance of single APs but not the bursts of APs. This suggests that some components of the response are synaptically evoked in ortho- and antidromic stimulations. The remaining spikes reflect conduction of excitation along continuous nerve fibers. Transmural electrical stimulation leads to either increase or decrease in the spontaneous firing rate of neurons except the cells generating stable burst-like firing. Reasons and significance of these changes are discussed.

[Effect of methylene blue on spontaneous and evoked reactions in the autonomic neuromuscular junction]. / Deistvie metilenovogo sinego na spontannye i vyzvannye reaktsii v avtonomnom nervno-myshechnom soedinenii.

The action of a vital neurotropic dye methylene blue on spontaneous and posttetanic reactions in the autonomic neuromuscular junction was studied with the sucrose gap technique. Low concentrations of methylene blue (10(-5)-10(-6) g/ml) increased the frequency of APs in spontaneously active cells and induced APs in silent cells while high concentrations of methylene blue (10(-3)-10(-4) g/ml) showed the biphasic excitatory-inhibitory action. Similar changes occurred in the excitatory phase of posttetanic response of smooth muscle cells, although the amplitude and duration of synaptic potentials remained unchanged. The stability of reactions after injection of methylene blue simultaneously with ganglio-, adrenoblocking agents and atropine as well as elevated Mg2+, suggests unspecific action of the methylene blue molecule on the muscle cell membrane. The observed phenomena were of shortlasting type and disappeared after washing with normal nutrient medium.

[Activity of enteric ganglion cells with intact and disrupted interganglionic connections]. / Aktivnost' kletok énteral'nykh gangliev s intaktnymi i narushennymi mezhganglionarnymi sviaziami.

Spontaneous unit activity in enterometasympathetic ganglia with intact connections was arrhythmic or quasirhythmic; low-, middle- or high-frequency; single or in trains or mixed. The units appear to be evenly distributed. Successive transection of interganglionic projections reduces the number of units with the spontaneous activity. The quasirhythmic activity existed in completely isolated and major ganglia. Blocking agents and an increase of magnesium ions revealed that the rhythmic activity was endogenous and specific for pace--maker cells. Only a chain of 5--7 interconnected ganglia had all types of the spontaneous activity. Such a complex of ganglia seems to be the most probable functional module of metasympathetic ganglia.

[Effect of cholinergic substances on electrical processes in a ganglion of the enteric nervous system]. / Deistvie kholinergicheskikh veshchestv na élektricheskie protsessy v ganglii énteral'noi nervnoi sistemy.

In the isolated in vitro segments of cat small intestine the sensitivity of myenteric neurons was studied by means of application of acetylcholine, nicotine, lobeline. The action of these drugs depended on their concentration: 10(-10)--10(-6)g/ml usually increased while larger concentrations (10(-5)g/ml) decreased the spontaneous activity. The preliminary application of d--tubocurarine (10(-6)g/ml), hexamethonium (10(-7)g/ml), and atropine (10(-6)g/ml) prevented the excitatory effects or suppressed neuronal discharges. The alteration of spontaneous activity seems to depend on the postsynaptic action of cholinergic drugs in M- and N-cholinoreceptors.

[Adrenosensitive neurons of the myenteric (Auerbach's) plexus]. / Adrenochuvstvitel'nye neirony miénteral'nogo (Auérbakhova) spleteniia

Experiments were conducted on the myenteral plexus of the isolated stips of the small and large intestine; the presence of adrenosensitive cells which reacted to the application of different adrenaline (A) and noradrenaline (NA) concentrations by a distinct acceleration of the activity rhythm was demonstrated. NA with a greater range of action than A (from 10(-9) to 10(-5 g/ml) has the most marked effect. Introduction into the irrigating solution of phentholamine eliminated the mentioned effects in the majority of cases. "Silent" neurons without any spontaneous activity responded to the A and NA administration along with those possessing this activiy. As supposed, catecholamines could take a direct part in the modulation of the processes realized by the ganglionic neurons of the myenteral plexus.

[Spontaneous activity of myenteric plexus neurons in the intact rabbit small intestine]. / Spontannaia aktivnost' neironov mienteral'nogo spleteniia intaktnoi tonkoi kishki

In rabbits intact myenteric plexus segments of the intestine, two types of neurons in regard to their electric discharges, were found: 1) units with single spontaneous spikes at the mean firing rate 2.3/sec and with interspike intervals from 140 to 900 msec; 2) units firing bursts of 3--12 spikes with interspike intervals of about 30 msec.