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To obtain information about the regulating nervous mechanisms of the pig alimentary canal the activity of monoaminooxidase (MAO) and acetylcholinesterase (AChE) in duodenum, jejunum and colon was studied during the embryonal and postnatal growth. The activity of monoaminooxidase was measured manometrically according to the method prepared by Kolb and that of acetylcholinesterase colorimetrically according to Hestrin's method. It was found that the activity of MAO and AChE in different parts of the pig alimentary canal was considerably differentiated during ontogenesis. Presence of these enzymes was already shown in the embryonal period. However, their activity was poor and almost on the same level in all the examined parts of intestines. Rapid increase of activity of both enzymes was immediately after pigs birth at the time between parturition and fifth day of postnatal life. In the later period of life (6-11 days after birth) there was a decrease of activity of both MAO and AChE only in duodenum. But in jejunum and colon there was a further, slight though, increase of the activity of both enzymes. Comparing the activity of MAO and AChE in the individual parts of the mature pig intestine with the embryonal and postnatal periods, it was found that in spite of the considerable increase of activity of both enzymes after birth, their level was smaller than that in the mature animals.

The studies have been carried out in vitro on the colons of 25 rabbits. The material was collected according to the Garry and Gillespie technique. The preparations consisted of the distal region of the colon together with the branches of parasympathetic nerves (pelvic ones) and with the sympathetic nerve (hypogastric). The conductivity was studied by the method of stimulation of these nerves branches with the 10 V impulses, 5 s long frequency 50-100 Hz, every 2-4 minutes. Spontaneous colon motoricity was registered on the kymograph in the chamber with oxyzenized Krebs fluid, according to the Magnus method. 0.3-10.0 ml of the bile per 1 l of the Krebs fluid was administered to the chamber. The same quantities of the physiological salt solution were administered to the chamber as the control. As for the chemically pure biliary acids, the cholic, deoxycholic and chenodeoxycholic acids (Light) were administered in quantities 500-1500 mumoles/l of the Krebs solution, as well as litocholic acid (Serva) in the concentration 300-500 mumoles/l. The control was carried out exactly as previously described. It has been found out that bile can inhibit or stimulate the colon motoricity and the nerves conductivity, depending on its concentration. At the small concentration (0.3 ml/l of the Krebs fluid) the bile stimulated the spontaneous colon motoricity and the conductivity of the sympathetic as well as the parasympathetic nerves. The high concentration (10 ml/l) had the inhibition effect on the colon motoricity and suppressed the nerves conductivity. As for the biliary acids, the strongest inhibitory effect had the litocholic acid, the weaker inhibitory effect had the cholic and deoxycholic acids. The chenodeoxycholic acid suppressed the nerves conductivity but stimulated the colon motoricity and increased the constriction amplitude.

The studies were carried out in vitro on the jejunum of 10 pigs, 10 rabbits and 10 guinea pigs. The activity monoaminooxidase (MAO) was determined manometrically in Warburg's apparatus, that of acetylcholinesterase (AChE) spectrophotometrically after Ellman's method modified by urek and Syrowatka. The obtained results were statistically analysed. It was shown that in the animals studied the bile acids exerted a considerable effect on the activity of enzymes metabolising neurohormones. Under the influence of bile the activity of monoaminooxidase was inhibited. Stimulating, but less distinctly, bile effected the activity of acetylocholinesterase. Significant differences in the action of bile on the activity of these enzymes were found in the jejunum of the animal species studied. The highest decrease in the activity of MAO under the influence of bile was found in the jejunum of the rabbit (by about 65%), a weker in the pig (by 37.5%) and guinea-pig (by 18.5%). However, the highest increase in the activity of AChE under the influence of bile occurred in the pigs (by about 21.6%), a weaker in the rabbit (by 16.4%) and guinea-pig (by about 11.5%). Among the bile acids, the strongest action on both the activity of MAO and AChE was exerted by lithocholic acid, desoxycholic, weaker by cholic and chenodesoxycholic acid. MAO activity under the influence of lithocholic acid decreased (in the pig by about 63%, rabbit by 55.7% and guinea pig by 34.8%). After incubation of the jejunum in desoxycholic acid a decrease in MAO activity occurred (in the rabbit by 43.8%, pig by about 39.4% and guinea-pig by 15.7%). AChE activity under the influence of lithocholic acid increased (in the pig on average by 62.2% rabbit by 21.8 and guinea-pig by about 10.2%). After incubation of the jejunum in desoxycholic acid an increase in the activity of acetylcholinesteras occurred (in the pig by about 13.5%, guinea-pig by 7.7% rabbit 7.3%).

The aim of our study was to describe the effects of bile and bile acids action on the spontaneous motor activity of the rabbit small and large intestines. The following fragments of intestines were used: duodenum, jejunum, ileum, caecum and colon of 25 rabbits of both sexes, weighing 2-3 kg. The motor activity of the isolated fragments of the intestines was recorded by the suspension method in a 300 ml container with oxygenated Krebs' solution, temp. 37 degrees C (constant), pH 7.8. The intestine was connected with the miograph constructed according to the Gillespie method. Vesicular bile was given in the amounts 0.3-10 ml per 1 l of the Krebs' solution. Chemically pure bile acids were also given as follows: cholic acid (Light) and chenodeoxycholic acid (Light) in the amount 500-1500 mumol/l of the Krebs' solution and lithocholic acid (Serva)--300-500 mumol/l. 0.33 ml/l of the Krebs' solution of the bile caused the threshold reaction, and only in the jejunum caused distinct inhibition of the motor activity. In duodenum, ileum and colon the inhibition time was very short, intestines quickly regained initial activity, and, what is more, frequency and amplitude of spasms were even greater. Big doses of the bile usually inhibited the motor activity of the studied intestine fragments, eliminating completely--with the exception of caecum--the spasms' amplitude, without releasing any relaxation reaction. As for the bile acids, the strongest inhibiting effect had lithocholic acid but, unlike bile, it caused the relaxation reaction.