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The work studied effect of various concentrations of nifedipine on the slow and fast spontaneous activities evoked in the perivesical and perirenal areas of the rat ureter. Whereas in the proximal zone of the organ at the low dose of nifedipine (0.06 and 0.12 mg/kg), inhibition is revealed both of slow waves and of their corresponding spikes, in the perivesical part the opposite effect is observed. Besides, with further increase of the nifedipine dose to 0.15 and 0.2 mg/kg, in the ureter area adjacent to the urinary bladder, alongside with acceleration of slow pacemaker oscillations, the appearance of the antiperistaltically directed action potentials is also possible.

The work present data indicating no dependence of the pacemaker activity located in the zone of junction of cat ureter with urinary bladder on genesis of the main perirenal pacemaker. Data are presented on effect of clamping the renal artery supplying with blood flow the renal area on rhythmogenesis of the ureter perivesicular area. An inhibition of the pacemaker activity of the pyeloureteral anasomosis is observed. At the same time, no marked effect on automatism of the low organ area is revealed. Data of morphological studies of the vascular bed providing blood supply of various ureter areas are presented.

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.

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).

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.

Electrical activity of the ureter pericystic region was found to have a definite own rhythm. Noradrenaline and adrenaline were able to induce rhythmic activity in previously inactive pericystic areas. The existence of pacemaker area in the ureter pericystic region seems to act as an additional system for coordination of polarity of the excitation-contractile waves.

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.

The ionic nature of each of the two slow wave depolarization phases of cat's ureter pacemaker during i.a. perfusion of kidneys, was studied. An increase of the calcium ions concentration led to an increase in the second wave phase amplitude, lengthening of the first phase and a decrease in the wave generation frequency. A decrease of the sodium ion concentration also led to an increase in the oscillation frequency with a corresponding shortening of the first phase. In sodium-free solution, during a short interval of time slow wave generation was observed which represented usually the second wave component. But for the autooscillations to get steady, the presence of sodium ions in medium is necessary. The Na+/Ca++ system seems to participate in the generation of the first wave phase.