[The characteristics of the electrical activity of the human colon recorded noninvasively]. / Kharakteristika na elektricheskata aktivnost na kolona u chovek, registrirana neinvazivno.

In ten healthy volunteers and ten patients with diseases involving the upper section of the gastrointestinal tract (chronic cholecystitis, chronic gastritis) the electrical activity of the colon is registered noninvasively using skin electrodes to the projection site of sigmoid and colon descendens. Recordings are taken with original gastrograph. Apart from the electrocolograms (EColG), the changes in intracolonic pressure in the group of 10 patients are also registered. Pressure recordings (mechanogram--MG) are done in physioscript "Hellige". Two types of EColG waves are identified depending on their frequency: 1) type A waves with frequency 5.86 +/- 0.59 cpm, and 2) type B waves with frequency 2.35 +/- 0.25 cpm. Type A are low-amplitude waves and correspond to the type A waves seen in the EColG of dogs (described by the authors elsewhere), characterizing the calm period of colonic motility. When A waves appear in the EColG no changes in the mechanograms are registered. Type B are high-amplitude waves, corresponding to the B waves in dogs (described elsewhere); as shown by the mechanograms, the appearance of B waves in the EColG is followed by the appearance of high-amplitude waves--the active period of colonic motility. There is a significant difference between the frequencies of either type of EColG waves and the frequency of waves in the electrogastrograms (EGG) registered synchronously with EColG.

Nitric oxide modulates cholinergic neurotransmission in cat duodenum.

1. Longitudinal muscle strips isolated from cat proximal duodenum were characterized by spontaneous phasic contractions. 2. Electrical field stimulation (EFS) (0.5 ms, 1-20 Hz, supramaximal voltage intensity for 40 sec) produced frequency-dependent contractions, and maximal amplitude was achieved at 10 Hz. The EFS-induced contractions were abolished either by atropine (10(-6) M) or by tetrodotoxin (3 x 10(-7) M). 3. The nitric oxide (NO) synthase blocker N infinity-nitro-L-arginine (L-NNA, 10(-4) M) or the inhibitor of the soluble guanylyl cyclase methylene blue (MB, 3 x 10(-5) M) increased the amplitude of the electrically evoked contractions. 4. L-Arginine (10(-3) M) or sodium nitroprusside (SNP, 10(-4) M) significantly decreased the amplitude of the EFS-induced, L-NNA- or MB-potentiated contractions as the effect of SNP was much more pronounced. 5. Neither L-NNA nor MB affected the contraction evoked by exogenous acetylcholine. 6. The L-NNA or MB-induced interruption of the L-arginine-NO pathway potentiated the electrically evoked cholinergic contractions, suggesting the inhibitory role of NO in the cholinergic neurotransmission realized probably at the pre-synaptic level in cat duodenum.

Non-invasive electrocologram: correlation between the electrical activity of the dog colonic muscle wall recorded by cutaneous and implanted electrodes.

Chronic experiments were performed on dogs with silver, bipolar, ball-shaped electrodes implanted on the colonic and of the gastric muscle wall. Cutaneous electrodes were placed on the abdominal wall, along the projection of descending colon and also of the stomach, at the beginning of each experiment. Slow waves were led off in the electrocolomyogram (EColMG), corresponding to low-amplitude waves in the non-invasive electrocologram (EColG) with a frequency of 6.39 +/- 0.58 cpm (type A). When bursts of spike potentials appeared with the slow waves in the EColMG, increase of the amplitude of the EColG waves and decrease of the frequency (1.90 +/- 0.20 cpm) was observed. There was a significant difference between the colonic wave frequency and the frequency of the gastric waves (3.96 +/- 0.28 cpm). A good correlation was found between the number and frequency of the spike potentials in a group in the EColMG and the wave amplitude in the EColG. A sequence of low-frequency, high-amplitude waves (type B) characterized an activity period, while a sequence of low-amplitude, high-frequency waves (type A) corresponded to a quiescent period of the colonic motility. Thus the functional state of the colonic muscle wall could be judged by the differences in the frequency and amplitude of the EColG waves.

Non-invasive electrocologram: non-invasive recording of the human colonic electrical activity.

The electrical activity of the descending colon of fifteen healthy volunteers was recorded non-invasively by cutaneous electrodes sticked on the abdominal wall along the descending colon projection--electrocologram (EColG). The electrical activity of the colon and stomach was recorded by an original electrogastrograph. The means, S.E.M. of the frequency of the colonic and gastric waves were calculated. Parallel studies of the EColG and the changes in the intracolonic pressure were performed on 10 patients with balloon inflated in the colon. Two kinds of EColG waves according to their frequency were identified: i) Type A waves with a frequency of 5.86 +/- 0.59 cpm and ii) Type B waves with a frequency of 2.35 +/- 0.25 cpm. There was a significant difference between the frequencies of the EColG waves and the frequency of the EGG waves -3.35 +/- 0.31 cpm. The type A waves were of low amplitude and corresponded to type A dog colonic waves i.e. they characterized the quiescent period of colonic motility. Type B waves were with a high amplitude, corresponded to type B dog colonic waves and characterised the activity periods of colonic motility. This was confirmed by the correspondence between type B waves and the changes in the intracolonic pressure. Thus the proposed non-invasive electrogastrographic method proved to be suitable for non-invasive registration of the electrical activity of the human colon.

[The reactivity of canine colonic and ileal smooth muscle to carbachol (Jestryl)]. / Reaktivnost na gladuk muskul ot kolon i ileum ot kuche kum karbakhol (Jestryl).

Experiments were carried out on longitudinal and circular smooth-muscle strips isolated from the ileum and colon of healthy dogs (controls) and of dogs with local peritonitis. The changes in the contractile responses of the strips to carbachol administered cumulatively were studied, and the EC50 and pD2 values were calculated from the dose-response curves. For the colonic longitudinal strips the EC50 was 6 x 10(-8)M and the pD2 was 7.58. The pD2 for the ileal longitudinal strips was 7.83. The pD2 value for the circular strips from the ileum and colon was 7.19 and 8.87 respectively. In the dogs with local peritonitis, the sensitivity of the longitudinal strips to carbachol was higher (the pD2 for the ileum was 7.86 and for the colon-7.21) as compared to the circular strips (the pD2 for the ileum was 6.22 and for the colon-6.65). The affinity of the cholinoreceptors in the ileal circular strips to carbachol was decreased as compared to controls.

Relationship between the spike activities of the small and large intestines.

Experiments were performed using chronically implanted electrodes on the dog smooth muscle wall of the stomach and of the small and large intestines. Electrical activity of the muscle wall was recorded before and after feeding. When reaching the terminal ileum the active part of the migrating myoelectrical complex (MMC) continuously induced bursts of spike potentials superimposed on the slow waves. This electrical activity spread to the ascending colon. We also showed the existence of a spike activity on the terminal ileum independent of the MMC (appearing during the phase 1) and propagating to the colon. A relationship between the spike activities of the small and large intestines was also present after feeding. Beside the well-known gastro-colic reflex, we observed an increase in the spike activity of the terminal ileum and ascending colon between the 4th-5th hours after feeding. This probably corresponds to the arrival of the first portions of contents, evacuated from the arrival of the first portions of contents, evacuated from the stomach, and of the last portions of small intestinal contents. In conclusion, there is a relationship between the spike activities of the small and large intestines in starving animals and after feeding, and the terminal ileum plays a substantial role in this relationship.

Changes in the responsiveness of the colonic smooth muscle to carbachol in Hirschsprung's disease.

In vitro experiments were performed on smooth-muscle strips cut out in longitudinal and circular direction from the colon of Hirschsprung's patients who underwent an operation and from patients operated on for tumors of the sigmoid colon and rectum, serving as controls. The changes in the contractile activity of the smooth-muscle strips after carbachol applied cumulatively were examined and dose-response curves were plotted. The EC50 values for the circular strips from the aganglionic part of the colon were 6 x 10(-7) M in Hirschsprung's patients and 3.7 x 10(-8) M in control patients: the pD2 values were 6.23 and 7.43, respectively. This showed that the affinity of cholinoreceptors in the aganglionic part of the colon for carbachol was 16 times lower in Hirschsprung's patients as compared to control patients. The EC50 values for longitudinal strips from the ganglionic part of the colon were 2.6 x 10(-7) M in Hirschsprung's patients and 4 x 10(-8) M in control patients; pD2 values were 6.6 and 7.4, respectively. The affinity of cholinoreceptors in the smooth muscle of the ganglionic part of the colon for carbachol was also decreased (nearly 6.5 times) in Hirschsprung's patients as compared to controls.

Acetylcholine release in two parts of the canine ileum.

1. Electrically-induced contractions and acetylcholine (Ach) release in two parts of the ileum: 5 and 25 cm proximal to the ileo-colic sphincter (ICS) were compared. 2. The amplitude of electrically- and Ach-induced contractions of the ileum 5 cm proximal to the ICS (terminal ileum) was much higher than the amplitude of the contractions of the ileum 25 cm proximal to the ICS. 3. The amount of Ach released in the ileum 25 cm proximal to the ICS accounted for 58% of the amount of Ach released in the terminal ileum, which was taken to be 100%.

The role of the pelvic nerves in the realization of the reservoir function of the colon.

In situ experiments were made on a group of dogs and in vivo experiments on another group of dogs with implanted electrodes for recording the electrical activity of the colonic muscle wall. A bipolar platinum electrode implanted in the pelvic nerve entering into the distal area of descending colon was used for electrical stimulation of the nerve (1 ms impulse duration, frequency of 2, 8, 10 and 15 Hz and amplitude of 10, 15 or 20 V). Electrical stimulation of the pelvic nerve with a frequency of 2 Hz resulted in inhibition of the spike activity. However, groups of spike potential burst in the distal part of the descending colon in response to electrical stimulation with frequencies of 8, 10 or 15 Hz. Repeated stimulation caused spreading of the spike activity of the descending colon in oral direction until the transverse colon. These antiperistaltic waves probably prevented the propulsion of the content of the descending colon. Thus, in addition to the inhibitory effect exercised by the sympathetic and noncholinergic nonadrenergic inhibitory part of the intrinsic nervous system, the reservoir function of the colon is influenced by these orally spreading waves of spike activity (antiperistaltic waves), which are caused by impulses along the pelvic nerves.

On the mechanism of the smooth-muscle action of rosanol.

In vivo and in vitro experiments were performed to clarify some aspects of the mechanism of the smooth-muscle action of rosanol prepared from rose oil. On dogs (in vivo) and on isolated segments from guinea-pig ileum (in vitro) rosanol at high doses exerted a slight inhibitory effect on the activated gastrointestinal motility. The cholinolytic rosanol action proved in in vitro experiments, was found to play an essential role in the mechanism of its gastrointestinal motility-inhibiting effect. The present studies showed a pronounced antagonistic effect of rosanol on the KCl-increased Ca2+ level in rabbit aorta. It might be suggested that this effect of rosanol is also involved in the inhibitory action of rosanol on the activated gastrointestinal motility.