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Spontaneous electrical activity of the rat ureters per bladder zone was studied. In area of ureter connection with bladder, slow-wave activity was revealed. In bladder bordering ureter zone, rapid spike activity was found that was fully correlated with the genesis of upper located fluctuation processes.

Existence of two types of uncoordinated spontaneous activities of the cat ureterbladder area was shown: spikes and slow waves. The oscillation frequency of this area is two-fold lesser than the rhythm of renal waves. The activity concordance of these pacemakers occurs under conditions of ureter dissection in the middle. Normally pacemakers of this area seem to be a reserve mechanism of urine pushing through.

Histamine changed characteristics of the perinephric spontaneous spike activity and of the spreading electrical wave. It was shown that histamine could activate latent pacemakers of the ureter's middle area. Morphological picture of the histamine effect was also shown.

Characteristics of rhythmogenic pacemakers of the ureter's perirenal middle and peribladder region morphologically and electrophysiologically are analysed in guinea pigs both in presence of spreading activity and breach of conductivity. It was shown that the action potential's amplitude of the middle region is the highest and duration of the spike activities from perirenal zone is maximal and all three regions are characterised by different functional conditions.

Guinea pig's ureter rhythmogenic autonomous latent pacemaker was shown to generate a significantly higher-frequency rhythm than the pericystic pacemaker. The latent pacemakers of the ureter middle portion can be activated with a breach of electrical conductivity across the organ or with chemical agents (noradrenaline, histamine).

The rhythm generated by the peribladder area was found to be slower than that generated by the basis perirenal pacemaker in cats and rats. The antiperistaltic waves' frequency of the peribladder area was the lowest within the range of all the recorded rhythms.

A certain concentration of Dimedrol (0.5 x 10(-6) mol/l) turned out to be capable of neutralising the histamine regulation of the slow-wave activity. The histamine H1-receptors were shown to modulate the cat general pace-maker's activity as well as the Na+ mechanism of the slow wave genesis.

Histamine increased the oscillation frequency of the slow-wave activity in the cat ureter and changed the characteristics of the AP plateau phase. A specific and sensitive to histamine electrogenic Na/Ca agent seems to take part in generation of the ureter spontaneous activity.

The spontaneous activity of various zones of the guinea pig ureter was studied by means of "sucrose gap" technique. Two of these zones, perirenal and pericystic ones are pacemakers. An increase in the K+ ions amount in the medium, electric stimulation and administration of acetylcholine, histamine or noradrenaline induced rhythmic spikes in initially inactive middle regions of the ureter. At the same time, they reduced or blocked the activity of the pacemaker zones. The existence of the MP gradient along the ureter from the ends to its central regions, is discussed.

In presence of the specific Na(+)-K(+)-pump blocking agent ouabain reestablishment of spike activity of the ureter smooth muscle cells occurred, the latters having been preliminarily incubated in sodium-free solution. The reestablishment lasted not over 15 minutes. After substitution of calcium ions with barium ones, the period of the spike generation increased. The lithium ions are able to substitute the sodium ions for reestablishing the calcium action potentials. The ureter activity seems to be reestablished in sodium-free solution with participation of the Na+/Ca(++)-exchange mechanism, which is quite specific for the calcium ions.

I. a. perfusion of the Krebs solution of the cat ureter virtually altered characteristics of slow wave activity (SWA) observed with the blood circulation. Introduction of physiologically active substances into the solution restored some characteristics of the SWA. The SWA seems to depend not only on ionic exchange and properties of electrically controlled channels, but also on the set of native physiologically active substances.

The effects of Na-free medium, Na-K pump inhibitors, ATP and Ca++ ion antagonists in calcium channels (verapamil, Mn++) on the slow-wave spontaneous activity of the ureter pace-maker zone were studied under conditions of i. a. perfusion of kidney. A reduction of membrane potential oscillations was observed.

In sodium-free Krebs solution ureter cells are able to generate action potentials. Logarithm of time, during which spikes are generated, is in proportion to the concentration of calcium ions in the surrounding medium in interval from 2.5 to 15 mmol/l. The addition of 20 mmol/l Na+ ions into the external solution is able to reestablish prolonged electrical activity of ureter. In sodium-free solution it is possible the reestablishment of short duration activity which depends on K+ ions concentration in surroundings. It is supposed that intracellular concentration of calcium ions in ureter may be regulated with the help of Na+/Ca++ exchange mechanism.