Electrical Spike Activity Research Articles

Colonic myoelectrical activity and propulsion in the dog.

Electrical spike activity was recorded on the colon of the dog. The duration of the bursts of the spike was used to divide the spike activity into two different types: long and short spike bursts (LSB and SSB). LSBs lasted from 7 (ascending) to 37 sec (descending) and SSBs lasted about 1 sec, independent of the site. These measurements were applied to colons of colostomized dogs for which the colonic transit time was negatively correlated to the LSBs expressed as percent of the time. The effects of high- and low-residue diets were tested. Intake of large amounts of dry food was associated with an increase of the LSB activity. A meat diet was accompanied with an increase of the SSB activity. These results suggest a propulsive effect for the LSBs stimulated by large amounts of colonic contents while the SSB activity may reflect some degree of emptiness.

Electrical resistance and spike activity in tarsal chemosensilla ofPhormia regina (Meig.)

The relationship between hair electrical resistance and responsiveness to stimulation has been investigated in the tarsal chemosensilla ofPhormia regina. Results showed that the lower the hair electrical resistance, the higher is the spike-firing frequency.

Gastrointestinal myoelectric activity disturbances in gastric ulcer disease in rats and dogs.

Electrical spiking activity of the antrum, duodenum, and jejunum was recorded from chronically implanted electrodes in rats and dogs. Gastric ulceration was induced by physical restraint in rats and by indomethacin treatment in dogs. In rats, restraint caused a 30% reduction of intestinal slow-wave frequency. After restraint the basal electrical rhythm (BER) returned to normal but in ulcerated rats the amplitude of spike potentials decreased and the migrating myoelectric complexes (MMC) of fasting were abolished by a continuous irregular spiking activity. In dogs, the amplitude of spiking activity progressively declined after the 6th day of indomethacin treatment. The frquency of the canine MMCs during the interdigestive state decreased from 0.6 to 0.2 per hour in ulceraed dog. The duration of the postprandial disorganization increased from 8 to 20 hr. It is concluded that, independent of the ulcerogenic factors, gastric ulceration induced both a reduction of the amplitude of the intestinal spiking activity and disruption of the MMCs.

Influence of dietary fiber on transit time, fecal composition, and myoelectrical activity of the primate right colon.

The effect of varying dietary fiber intake on colon motor and electrical spike activity, transit time, and fecal content were studied in stump-tailed monkeys. Mean dry fecal weight increased with increasing fiber intake, but percentage water content did not change. Mean transit time was delayed when the diet contained less than 10 g dietary fiber daily. The clearance of polyethylene glycol and chromium sesquioxide also was slower on a low-fiber intake. Electrical spike discharge activity was greatest in the cecum and increased with increasing fiber intake. The effect of fiber on electrical spike activity progressively decreased distally along the colon. The contraction frequency of circular muscle, recorded with implanted strain gages, was greater in the cecum on a low-fiber diet, but this effect was less marked in transverse colon, and no significant differences were seen more distally.

Propagation of electrical spiking activity along the small intestine: intrinsic versus extrinsic neural influences.

1. The electrical activity of the small intestine of conscious dog, recorded by means of chronically implanted electrodes, was related to the transit time estimated by phenol red infusion and its propagation observed after a single or double transection and following either isolation or removal of a 50 cm jejunal loop. 2. In the fasted dog, the activity was characterized by the propagation of myoelectric complexes at a velocity of 4 cm/min during which the mean transit time averaged 13 min/m. About 2/3 of these complexes were seen to pass beyond a single section and anastomosis of the jejunum with a delay of 15 min. This number was reduced to 1/3 and the delay doubled when a second section was performed 50 cm distally. 3. In dog with an isolated jejunal loop, most of the myo-electric complexes were seen to pass from the proximal intestine to the loop and then to the intestine beyond the sit of anastomosis within 37 min. Some complexes however passed directly through the anastomosis within 30-32 min, affecting or not the loop. Others started on the loop and/or on the intestine beyond the anastomosis. Finally, the total number of complexes recorded on the distal jejunum was greater than on the duodenum, an effect which disappeared after removal of the isolated loop. 4. The propagation of the complexes occurred at a lower velocity after denervation of a jejunal segment in situ but was arrested in the case of an isolated-denervated jejunal loop. 5. It is concluded that continuity of structures in the bowel is essential for the propagation of a myo-electric complex which is stopped and replaced by another complex at the level of an anastomosis, the number os complexes reorganized beyond an anastomosis and their velocity of propagation depending upon both intrinsic and extrinsic neural influences.

Electrical spike activity in the human small intestine. A multiple electrode study of fasting diurnal variations.

An intraluminal probe with 10 pairs of bipolar electrodes was used for continuous recording of myoelectric activity along the entire small intestine during 24 hr in 2 normal fasting human subjects. Two types of regular migrating activity were observed: (1) Bands of a great number of spike potentials appearing at hourly intervals migrating through the entire small intestine. This activity corresponds to phase III of the "interdigestive myoelectric complex" described in animal experiments. (2) Bursts of a few spike potentials appearing with minute intervals migrating only through the jejunum. This activity has not previously been demonstrated in man nor in intact animals, but corresponds to the "minute-rhythm" described from in vitro experiments.

Migrating electrical spike activity in the fasting human small intestine.

The purpose of the present investigation was to describe characteristics of migrating electrical phenomena in the human small intestine. A specially designed probe with several bipolar electrodes was placed in the upper small intestine of 5 normal, fasting volunteers for continuous registration of electrical spike potentials. A migrating myoelectric complex was observed resembling observations made previously in animal experiments. The active phase consisted of regular spike potentials propagating distally at a mean velocity of 12 cm/min, and a duration of about 5 min. In addition a "peristaltic rush" was observed consisting of spike potentials with a high amplitude, propagating distally at a mean velocity of 2 cm/sec and a duration of about 5 sec.

Effects of anesthesia and surgical procedures on intestinal myoelectric activity in rats.

Electrical spiking activity of the duodenum and jejunum was recorded from chronically implanted electrodes in rats during volatile or barbiturate anesthesia and following laparotomy. The normal pattern of electrical spiking activity in the fasted rat, with myoelectric complexes at 15-min intervals, was transiently replaced by quiescence during ethyl ether anesthesia. A slight increase in irregular spiking activity occurred after induction with pentobarbital, and the only effect of thiopental anesthesia was a reduction in the velocity of propagation of the complexes by 20%. Under barbiturate anesthesia, incision of the skin did not inhibit myoelectric activity, but incision of each abdominal muscle layer had an immediate and transient inhibitory effect; the deeper the layer, the longer was the inhibition. Peritoneal incision consistently produced inhibition of spiking activity which was prolonged by exposure of the bowel to air and intestine handling. The inhibitory effects produced by surgery persisted after vagotomy or transection of the spinal cord at the thoracic level but disappeared after splanchnicectomy. The above results suggest that a somatovegetative reflex with efferent pathways in the splanchnic nerves is involved in the first stage of operative inhibition of intestinal myoelectric complexes.

Postoperative intestinal motility in dogs and sheep.

Electrical activity of the small intestine was recorded from chronically implanted electrodes in dogs and sheep. The effects of laparotomy and surgical procedures were identified under general anesthesia. Laparotomy induced in both species a complete inhibition of electrical spiking activity during the stage of muscular and peritoneal incision. The inhibitory period due to laparotomy was shorter in dogs than in sheep and in both species less marked at the duodenal level. A secondary period of inhibition (ileus) lasting from 6 hr for a resection of the colon to 24 hr for a transection of the small bowel was observed in dogs after a transient phase of normal activity during 3-6 hr. The period of inhibition due to abdominal surgery lasted from 48 to 72 hr and occurred at the time of surgery in sheep. In both species, inhibition due to laparotomy and surgical procedures was prevented by splanchnicectomy. The results showed that myoelectric activity of the different parts of the small intestine is specifically inhibited and/or disorganized through peripheral reflex pathways. They are activated at different degrees by laparotomy and abdominal surgery.

A unique distribution of laxative-induced spike potentials from the small intestine of the dog.

The effects of castor oil and ricinoleic acid on small bowel electrical activity were studied in the fasted conscious dog and were compared to the effects elicited by two nonlaxative oils (triolein and oleic acid). Spike potential activity was monitored at two jejunal sites using unipolar recording electrodes. Castor oil, ricinoleic acid, and triolein produced an increased incidence of basic electrical rhythm (BER) with associated spike potentials when compared to a fasted control; however, the total electrical spiking activity produced by these oils was not statistically different from that induced by feeding. No treatment altered any of the characteristics of BER. A novel pattern of electrical spiking activity was observed in response to the laxatives. This pattern consisted of short repetitive bursts of spike potentials which migrated the length of the recording site. The laxative-induced electrical pattern persisted for several days after treatment with ricinoleic acid or castor oil, and interdigestive patterns were occasionally interrupted for as long as 72 hr. Electrical activity following feeding or the nonlaxative oils consisted of random spike potentials, and normal interdigestive electrical activity resumed within 24 hr. The laxative-induced electrical pattern was shown to be quantitatively distinct from those produced by feeding, fasting, or nonlaxative oils. This pattern may reflect an action of these laxatives on intestinal motility during a diarrheal state.

Electrical Spiking Activity and Propulsion in Small Intestine in Fed and Fasted Rats

Bipolar electromyograms were obtained from electrodes chronically implanted on the small intestine in rats accustomed to receiving food only during 4 days per week. Continuous recording, begun 5 to 10 days after operation, continued for 10 to 15 days. The spiking activity was continuously summed at 20-sec intervals on linear integrators. At the end of the experiment, small intestinal propulsion and gastric emptying were measured. During fasting, the pattern of spike bursts of the jejunum was a cycle of three phases: a period of silence was followed sequentially by periods of irregular and regular spike bursts, lasting 6 to 10 min and 4 min, respectively. Cycles recurred at intervals of 16 to 20 min and migrated caudad at 2 to 3 cm per min. Intragastric administration of food and amino acids caused continuous irregular spiking for 2 to 3 hr. A similar effect resulted from amino acids and glucose administered into the duodenum. Continuous but weak irregular spiking followed intragastric or intraduodenal administration of oleic acid. In fasted rats, the velocity of intestinal transit was faster when a bolus was administered before a migrating complex than after Marker movement was rapid in fed rats in whom there was continuous irregular spiking. The presence of nutrients in the intestinal lumen alters the patterns of contractions.

Effects of pentagastrin on electrical activity of small intestine of the dog.

Effects of pentagastrin on electrical activity of small intestine of the dog.

Adrenergic excitatory influences on initiation and conduction of electrical activity in the rat portal vein.

AbstractThe longitudinal smooth muscle of the rat portal vein shows synchronized spontaneous contractions. Both initiation and propagation of this activity are of myogenic nature. Under the influence of noradrenaline (NA), or postganglionic nerve stimulation, the contraction frequency is known to increase markedly. In order to analyse pacemaker function and synchronization of activity in the isolated portal vein, both during spontaneous activity and during NA induced excitation, a method was designed which allowed simultaneous recording of the mechanical contractions and of the electrical activity from three separate areas in the preparation.Spontaneous, intermittent bursts of electrical spike activity spread over the preparation at a velocity of 5 to 30 mm/sec. Each propagated burst was associated with a mechanical response. Evidence is presented indicating that the individual spike potentials within a burst were propagated. Administration of exogenous NA markedly increased the frequency of burst discharge from an active pacemaker area, so that the preparation became synchronously driven at a higher rate, eventuelly leading to a maintained tetanus. In addition, propagated activity from “ectopic” pacemaker areas appeared, which caused irregular contractile responses. Qualitatively similar activity patterns were obtained by tyramine administration. The pronounced synchronization, and the increase in frequency of burst discharge elicited by such release of endogenous NA, suggest that myogenic propagation plays a most important role in the effectiveness of nervous control of this type of vascular smooth muscle.

Effects of strychnine and gamma-aminobutyric acid on spike and wave activity in the frog telencephalon

In the paleopallium of the frog it is possible to evoke by electrical stimulation paroxysmal spike and wave activity which is in its shape and frequency characteristics very similar to the analogous electrographic seizure phenomena in the mammalian brain. In previous experiments it was demonstrated that the surface-negative slow wave of the spike and wave complex is accompanied by prolonged negativity in the dendritic layer of the pallium. The present paper presents further analysis of the electrogenesis of the spike and wave complex in the pallium of the frog. The changes of the surface electrogram and of unit activity in the granular layer were evaluated after application of strychnine and gamma-aminobutyric acid. Neither local nor general application of strychnine changed significantly the shape and frequency of the surface spike and wave electrogram, or the amount and time distribution of unit activity during the seizure. Gamma-amino butyric acid, applied locally, suppressed the negative wave in the surface electrogram, changing the spike and wave activity into an activity of slow surface-positive spikes. At the same time, unit activity in the granular layer was augmented. The results are interpreted in the sense that the wave of the spike and wave complex is the product of synchronized axodendritic EPSP in the dendritic layer, being at the same time an inhibitory correlate as regards unit activity in the granular layer of the pallium.