Myoelectric properties of the cat ileocecal sphincter

1981 ◽  
Vol 240 (6) ◽  
pp. G450-G458 ◽  
Author(s):  
A. Ouyang ◽  
W. J. Snape ◽  
S. Cohen
Keyword(s):  
Action Potential ◽  
Mechanical Stimulation ◽  
Spike Activity ◽  
Castor Oil ◽  
Proximal Colon ◽  
Wave Activity ◽  
Tonic Contraction ◽  
Myoelectric Activity ◽  
Spike Potential ◽  
Sphincter Function

Myoelectric activity and intraluminal pressures were recorded simultaneously from the ileum, ileocecal sphincter (ICS), and proximal colon in chloralose-anesthetized cats. Slow-wave activity, seen at all areas, showed coupling of frequency in the distal ileum and ICS. ICS spike activity was both isolated and associated with ileal or colonic spike activity and correlated with phasic contractions (r = 0.86; P less than 0.01). Ileal distensions caused ICS relaxation and decreased spike activity 33.8% of the time. Colonic distensions caused contraction and increased spike activity 46.9% of the time. Migrating action-potential complexes (MAPC) induced by castor oil, ricinoleic acid, or cholecystokinin propagated to the ICS and through to the colon significantly more frequently than ileal non-MAPC (P less than 0.05). Both spike potential-dependent and spike potential-independent mechanisms were involved in ICS contraction. Bethanechol increased spike activity and phasic and tonic contractions. Phenylephrine, despite loss of spike activity in all leads, caused tonic contraction of the ICS. Isoproterenol caused loss of spike activity and decreased ICS pressure. Thus, ICS myoelectric activity appears to be important in determining sphincter function during neurohumoral and mechanical stimulation, with ICS contractions occurring through both a phasic spike-related mechanism and a tonic mechanism without spike activity.

Effects of PGF2 alpha and of indomethacin on rabbit small and large intestinal motility in vivo

1990 ◽  
Vol 258 (2) ◽  
pp. G231-G237 ◽  
Author(s):  
R. Burakoff ◽  
E. Nastos ◽  
S. Won
Keyword(s):  
Terminal Ileum ◽  
Intestinal Motility ◽  
Contractile Activity ◽  
Distal Colon ◽  
Proximal Colon ◽  
Myoelectric Activity ◽  
Rabbit Ileum ◽  
Spike Potential ◽  
Potential Frequency

Prostaglandin F2 alpha (PGF2 alpha) has been shown to increase contractility in the small intestine and colon in vitro, and increased mucosal prostaglandin synthesis has been reported in ulcerative colitis. The purpose of this study was to determine the effects of PGF2 alpha and of indomethacin on myoelectric and contractile activity in the rabbit ileum and colon in vivo. PGF2 alpha caused an increase in spike potential frequency and contractile activity in the terminal ileum and proximal and distal colon. Indomethacin alone increased spike potential frequency and contractile activity in the terminal ileum and proximal colon but decreased myoelectric activity in the distal colon. It is concluded that PGF2 alpha may play an important role in modulating intestinal motility, especially in the distal colon but to a lesser extent in the terminal ileum and proximal colon.

Enhanced Dendritic Action Potential Backpropagation in Parvalbumin-positive Basket Cells During Sharp Wave Activity

2010 ◽  
Vol 35 (12) ◽  
pp. 2086-2095 ◽  
Author(s):  
Balázs Chiovini ◽  
Gergely F. Turi ◽  
Gergely Katona ◽  
Attila Kaszás ◽  
Ferenc Erdélyi ◽  
...  
Keyword(s):  
Action Potential ◽  
Wave Activity ◽  
Basket Cells ◽  
Sharp Wave

Opiate nerves mediate feline pyloric response to intraduodenal amino acids

1985 ◽  
Vol 248 (3) ◽  
pp. G307-G312 ◽  
Author(s):  
J. C. Reynolds ◽  
A. Ouyang ◽  
S. Cohen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Spike Activity ◽  
Saline Control ◽  
Myoelectric Activity ◽  
Neural Pathways ◽  
Acid Solutions ◽  
Cervical Vagotomy ◽  
Amino Acid Solutions ◽  
Dose Dependent

Intraluminal pressures and myoelectric activity were recorded from the feline antrum, pylorus, and duodenum in response to intraduodenal amino acid solutions. Mixed amino acids (0.02 mg/ml, 3.0 ml) increased the amplitude of pyloric contractions (59.7 +/- 7.9 mmHg) and pyloric spike activity (73.7 +/- 6.8% of slow waves with spike activity) compared with a saline control (P less than 0.001). The selectivity of these responses was determined with specific amino acids. L-Tryptophan (10 or 40 mM) produced a response similar to the mixed amino acid response, while L-phenylalanine or L-glycine (10 or 40 mM) had no effect. Intra-arterial tetrodotoxin, intraluminal ethyl aminobenzoate, or intravenous naloxone (1.0 mg/kg) abolished the pyloric responses to amino acids (P less than 0.02). Bilateral cervical vagotomy had no effect. Cholecystokinin octapeptide (CCK-OP) produced dose-dependent increases in the amplitude of pyloric contractions and in pyloric spike activity. The ED50 dose of CCK-OP (1.0 microgram/kg iv) gave an increase in pyloric pressure of 155.6 +/- 49.9 mmHg and in spike activity of 77.7 +/- 9.4%, similar to mixed amino acids or tryptophan. These effects of CCK-OP were not antagonized, however, by a dose of naloxone (1.0 mg/kg) that blocked the maximal pyloric response to leucine-enkephalin. We concluded intraduodenal mixed amino acids or tryptophan increase phasic, spike-dependent pyloric contractions in the cat via nonvagal, naloxone-sensitive neural pathways, phenylalanine, a structurally similar essential amino acid, had no effect on the feline gastroduodenal junction, and the pyloric responses to exogenous CCK-OP are mediated by pathways distinct from the responses to tryptophan or mixed amino acids.

Effect of calcium on neurohumoral stimulation of feline colonic smooth muscle

1982 ◽  
Vol 243 (2) ◽  
pp. G134-G140
Author(s):  
W. J. Snape
Keyword(s):  
Smooth Muscle ◽  
Spike Activity ◽  
Calcium Ion ◽  
Calcium Concentration ◽  
Extracellular Calcium ◽  
Ion Concentration ◽  
Myoelectric Activity ◽  
Ionic Calcium ◽  
Calcium Ion Concentration ◽  
Stimulation Of

The purpose of this study was to compare the effect of altering the extracellular calcium ion concentration on bethanechol or octapeptide of cholecystokinin (OP-CCK) stimulation of the isolated transverse colon of the cat. Myoelectric activity was recorded with monopolar glass-pore electrodes. Bethanechol (10(-6) M) stimulated an increase in the number of slow waves with superimposed spike potentials to 85.5 +/- 5.3% (P less than 0.001) compared with the basal spike activity (8.9 +/- 1.4%). OP-CCK (4 x 10(-9)) also increased spike activity (80.7 +/- 3.8%, P less than 0.001), which was not inhibited by atropine, phentolamine, or propranolol. Addition of 0.0 mM calcium solution to the colonic smooth muscle abolished both slow-wave and spike activity, which returned after replacing 0.25 mM calcium in the solution. Bethanechol stimulated a greater increase in spike activity as the concentration of calcium was increased. OP-CCK stimulation of colonic spike activity was more sensitive to the extracellular calcium concentration than bethanechol stimulation. Verapamil had a minimal effect on bethanechol stimulation of colonic spike activity, but it inhibited the OP-CCK stimulation. These studies suggest that 1) OP-CCK appears to stimulate colonic smooth muscle directly and 2) OP-CCK requires the presence of a greater amount of extracellular ionic calcium in order to stimulate colonic spike activity compared with bethanechol.

Escherichia coli heat-stable toxin: its effect on motility of the small intestine

1982 ◽  
Vol 242 (4) ◽  
pp. G360-G363 ◽  
Author(s):  
J. R. Mathias ◽  
J. Nogueira ◽  
J. L. Martin ◽  
G. M. Carlson ◽  
R. A. Giannella
Keyword(s):  
Escherichia Coli ◽  
Small Intestine ◽  
Action Potential ◽  
Myoelectric Activity ◽  
Complex Activity ◽  
E Coli ◽  
Heat Stable ◽  
Rabbit Small Intestine ◽  
Weight Substance

Escherichia coli heat-stable enterotoxin is a low-molecular-weight substance that has been shown to induce the active secretion of fluid and electrolytes in the small intestine. In this study, we have characterized the effects of purified E. coli heat-stable toxin (ST, strain 18D, serotype 042:K86:H37) on the motility of rabbit small intestine by using myoelectric recording techniques. Substances, such as cholera toxin, that activate the adenylate cyclase-cAMP system induced predominantly migrating action-potential complex activity. E. coli ST, a toxin that activates the guanylate cyclase-cGMP system, was infused into isolated in vivo ileal loops of New Zealand White rabbits. Inactivated toxin was also studied by exposing the ST to 1 mM dithiothreitol for 90 min. Active E. coli ST induced only repetitive bursts of action potentials. When the toxin was inactivated with dithiothreitol, no alteration in myoelectric activity was observed. We speculate that repetitive bursts of action-potential activity may represent a virulent factor of the bacterium, altering motor activity to slow transit and allowing for bacterial proliferation and invasion.

Role of prostaglandins in control of intestinal motility

1985 ◽  
Vol 248 (3) ◽  
pp. G353-G359 ◽  
Author(s):  
P. Thor ◽  
J. W. Konturek ◽  
S. J. Konturek ◽  
J. H. Anderson
Keyword(s):  
Spike Activity ◽  
Intestinal Motility ◽  
Myoelectric Activity ◽  
Physiological Control ◽  
Dependent Inhibition ◽  
Constant Dose ◽  
Dose Dependent Inhibition ◽  
Monopolar Electrodes ◽  
Dose Dependent Decrease ◽  
Dose Dependent

Intestinal myoelectric activity was measured in four conscious dogs with implanted monopolar electrodes after administration of prostaglandins (PG) and indomethacin (Indo), a potent inhibitor of PG biosynthesis. PGE2 and PGI2 given intravenously caused a dose-dependent decrease in the frequency of the migrating myoelectric complex (MMC) in fasted dogs and in postprandial spike activity in fed animals. In contrast, PGF2 alpha interrupted the MMC and caused a fedlike pattern in fasted dogs and did not affect the postprandial spike activity. Similar effects were observed after intra-arterial infusion of PGs. PGE2 and PGI2 infused into the superior mesenteric artery caused a dose-dependent inhibition of the fasted and postprandial pattern of myoelectric activity of the small bowel, whereas PGF2 alpha blocked the MMC and increased spike activity. Indo injected in a single intravenous dose caused a significant reduction in the MMC interval, and Indo infused intravenously in a constant dose induced fedlike motility pattern in fasted dogs but had little effect on the postprandial activity in these animals. This study demonstrates that exogenous PGs of E and I series administered intravenously or intra-arterially inhibit intestinal motility, whereas PGF2 alpha has opposite effects. The finding that Indo increases intestinal motility indicates that endogenous PGs are important in the physiological control of intestinal motility.

Modulation of Voltage-Activated Calcium Currents by Mechanical Stimulation in Rat Sensory Neurons

1998 ◽  
Vol 80 (4) ◽  
pp. 1647-1652 ◽  
Author(s):  
Yona Bouskila ◽  
Hugh Bostock
Keyword(s):  
Action Potential ◽  
Sensory Neurons ◽  
Mechanical Stimulation ◽  
Action Potential Duration ◽  
Calcium Currents ◽  
Dorsal Root Ganglion Neurons ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Low Threshold ◽  
Ganglion Neurons

Bouskila, Yona and Hugh Bostock. Modulation of voltage-activated calcium currents by mechanical stimulation in rat sensory neurons. J. Neurophysiol. 80: 1647–1652, 1998. We examined the effects of mechanical stress, induced by a stream of bath solution, on evoked action potentials, electrical excitability, and Ca2+ currents in rat dorsal root ganglion neurons in culture with the use of the whole cell patch-clamp technique. Action-potential duration was altered reversibly by flow in 39% of the 51 neurons tested, but membrane potential and excitability were unaffected. The flow-induced increases and decreases in action-potential duration were consistent with the different effects of flow on two types of Ca2+ channel, determined by voltage-clamp recordings of Ba2+ currents. Current through ω-conotoxin–sensitive (N-type) Ca2+ channels increased by an estimated 74% with flow, corresponding to 23% increase in the total high voltage–activated current, whereas current through low-threshold voltage-activated (T-type) channels decreased by 14%. We conclude that modulation of voltage-activated Ca2+ currents constitutes a route by which mechanical events can regulate Ca2+ influx in sensory neurons.

scholarly journals Diverse Ionic Currents and Electrical Activity of Cultured Myenteric Neurons From the Guinea Pig Proximal Colon

2000 ◽  
Vol 83 (3) ◽  
pp. 1253-1263 ◽  
Author(s):  
Fivos Vogalis ◽  
Kirk Hillsley ◽  
Terence K. Smith
Keyword(s):  
Patch Clamp ◽  
Guinea Pig ◽  
Action Potential ◽  
Action Potentials ◽  
Outward Current ◽  
Proximal Colon ◽  
Equilibrium Potential ◽  
Transient Outward Current ◽  
Myenteric Neurons ◽  
Fast Transient

The aim of this study was to perform a patch-clamp analysis of myenteric neurons from the guinea pig proximal colon. Neurons were enzymatically dispersed, cultured for 2–7 days, and recorded from using whole cell patch clamp. The majority of cells fired phasically, whereas about one-quarter of the neurons fired in a tonic manner. Neurons were divided into three types based on the currents activated. The majority of tonically firing neurons lacked an A-type current, but generated a large fast transient outward current that was associated with the rapid repolarizing phase of an action potential. The fast transient outward current was dependent on calcium entry and was blocked by tetraethylammonium. Cells that expressed both an A-type current and a fast transient outward current were mostly phasic. Depolarization of these cells to suprathreshold potentials from less than −60 mV failed to trigger action potentials, or action potentials were only triggered after a delay of >50 ms. However, depolarizations from more positive potentials triggered action potentials with minimal latency. Neurons that expressed neither the A-type current or the fast transient outward current were all phasic. Sixteen percent of neurons were similar to AH/type II neurons in that they generated a prolonged afterhyperpolarization following an action potential. The current underlying the prolonged afterhyperpolarization showed weak inward rectification and had a reversal potential near the potassium equilibrium potential. Thus cultured isolated myenteric neurons of the guinea pig proximal colon retain many of the diverse properties of intact neurons. This preparation is suitable for further biophysical and molecular characterization of channels expressed in colonic myenteric neurons.

Intestinal myoelectric alterations in rats chronically infected with the tapeworm Hymenolepis diminuta

1994 ◽  
Vol 267 (5) ◽  
pp. G851-G858 ◽  
Author(s):  
M. B. Dwinell ◽  
P. Bass ◽  
J. A. Oaks
Keyword(s):  
Small Intestine ◽  
Potential Gradient ◽  
Hymenolepis Diminuta ◽  
Phase Iii ◽  
Myoelectric Activity ◽  
Spike Potential ◽  
Bipolar Electrodes ◽  
Distal Small Intestine ◽  
Potential Activity ◽  
Interdigestive Motility

This study determined that intestinal myoelectric activity was profoundly altered during a strictly luminal, chronic, tapeworm infection. Chronically implanted bipolar electrodes were attached to five sites on the serosal surface of the rat small intestine. One was placed on the duodenum, three on the jejunum, and the fifth on the ileum. Electromyographic recording in nonfasted unanesthetized animals was begun at day 5 postsurgery. All electromyographic recordings were analyzed for slow wave (SW) frequency, phase III frequency, duration of phase III, and percentage of SW with spike potentials. Three initial control recordings prior to infection confirmed the presence of normal interdigestive motility characterized by the three phases (I, II, III) of the migrating myoelectric complex (MMC). Two nonpropulsive myoelectric alterations were observed in infected animals: the repetitive bursts of action potentials (RBAP) and periods of sustained spike potentials (SSP). Myoelectric activity from infected animals indicated decreased cycling of the interdigestive MMC. RBAP and SSP were more prevalent in the distal small intestine corresponding to tapeworm location. The percent of spike potential activity indicated that there was a reversal in the spike potential gradient on the small intestine. The number of spike potentials was maximal in caudal and minimal in oral intestine. We propose that overall localized increases in myoelectric spike potential activity represent increased contractility and decreased propulsion triggered by the presence of the tapeworm. These motility changes were surprising, since the tapeworm Hymenolepis diminuta does not penetrate the intestinal mucosa. This interaction between parasite and host may prevent expulsion of the tapeworm from the small intestine.

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