Effect of cromakalim and lemakalim on slow waves and membrane currents in colonic smooth muscle

1991 ◽  
Vol 260 (2) ◽  
pp. C375-C382 ◽  
Author(s):  
J. M. Post ◽  
R. J. Stevens ◽  
K. M. Sanders ◽  
J. R. Hume
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Slow Wave ◽  
Outward Current ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Ca Current ◽  
K Current ◽  
Stimulation Of

The effects of cromakalim (BRL 34915) and its optical isomer lemakalim (BRL 38227) were investigated in intact tissue and freshly dispersed circular muscle cells from canine proximal colon. Cromakalim and lemakalim hyperpolarized resting membrane potential, shortened the duration of slow waves by abolishing the plateau phase, and decreased the frequency of slow waves. Glyburide, a K channel blocker, prevented the effect of cromakalim on slow-wave activity. The mechanisms of these alterations in slow-wave activity were studied in isolated myocytes under voltage-clamp conditions. Cromakalim and lemakalim increased the magnitude of a time-independent outward K current, but cromakalim also reduced the peak outward K current. Glyburide inhibited lemakalim stimulation of the time-independent background current. Nisoldipine also reduced the peak outward current, and in the presence of nisoldipine, cromakalim did not affect the peak outward component of current. This suggested that cromakalim may block a Ca-dependent component of the outward current. Lemakalim did not affect the peak outward current. We tested whether the effects of cromakalim on outward current might be indirect due to an effect on inward Ca current. Cromakalim, but not lemakalim, was found to inhibit L-type Ca channels; however, glyburide did not alter cromakalim inhibition of inward Ca current. We conclude that the effects of cromakalim and lemakalim on membrane potential and slow waves in colonic smooth muscle appear to result primarily from stimulation of a time-independent background K conductance. The effects of these compounds on channel activity may explain the inhibitory effect of these compounds on contractile activity.

Selective lesioning of interstitial cells of Cajal by methylene blue and light leads to loss of slow waves

1994 ◽  
Vol 266 (3) ◽  
pp. G485-G496 ◽  
Author(s):  
L. W. Liu ◽  
L. Thuneberg ◽  
J. D. Huizinga
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Electrical Activity ◽  
Slow Wave ◽  
Interstitial Cells Of Cajal ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Cells Of Cajal

Incubation with 50 microM methylene blue (MB) and subsequent intense illumination resulted in abolition of the slow-wave activity in the submuscular interstitial cells of Cajal-circular muscle (ICC-CM) preparations of canine colon. This was often accompanied by a decrease in resting membrane potential. Repolarization of cells back to -70 mV did not restore the slow-wave activity, indicating that MB plus light directly interrupted the generation mechanism of slow waves. After MB incubation, a 2-min illumination consistently changed the mitochondrial conformation in ICCs from very condensed to orthodox, without inducing any obvious changes in smooth muscle cells. After 4- to 10-min illumination, ICCs became progressively more damaged with swollen and ruptured mitochondria, loss of cytoplasmic contrast and detail, loss of caveolae, and rupture of the plasma membrane. No damage was seen in smooth muscle cells or nerves. Gap junctional ultrastructure was preserved. Intense illumination without preincubation with MB left the slow waves and the ultrastructure of ICC-CM preparations unaffected. In CM preparations, without the submuscular ICC-smooth-muscle network, MB plus light induced no changes in electrical activity. We conclude that the correlation between selective damage to the submuscular ICCs (relative to smooth muscle) and selective loss of the slow-wave activity (relative to other electrical activity of the CM) strongly indicates that the ICCs play an essential role in the generation of slow waves.

Slow-wave activity in colon: role of network of submucosal interstitial cells of Cajal

1991 ◽  
Vol 260 (4) ◽  
pp. G636-G645 ◽  
Author(s):  
R. Serio ◽  
C. Barajas-Lopez ◽  
E. E. Daniel ◽  
I. Berezin ◽  
J. D. Huizinga
Keyword(s):  
Smooth Muscle ◽  
Slow Wave ◽  
Interstitial Cells Of Cajal ◽  
Circular Muscle ◽  
Interstitial Cells ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Plateau Potentials ◽  
Cells Of Cajal

The present study compares the electrophysiological properties of two preparations dissected from the canine colon circular muscle layer: first, containing the submucosal network of interstitial cells of Cajal (ICC) with two to four associated smooth muscle cell layers, and second, a circular muscle preparation devoid of the submucosal ICC network. In the ICC-rich preparations, consistent slow-wave activity was observed with prolonged plateau potentials of approximately 10-s duration. The plateau potentials were sensitive to D 600. In approximately 45% of circular muscle preparations devoid of the submucosal ICC network (confirmed using electron microscopy) slow waves, of different waveshape, were recorded at frequencies identical to those in whole circular muscle preparations. These slow waves did not show a plateau potential. Compared with ICC-rich preparations with a resting membrane potential of about -80 mV, circular muscle preparations had lower membrane potentials, about -70 mV when active, and about -60 mV when quiescent. Heptanol (1 mM) electrically uncoupled cells, since it abolished electrotonic current spread and allowed measurement of the input resistance by intracellular current injection. Heptanol also affected ionic conductances. Heptanol abolished slow waves; the underlying mechanism needs further investigation. In the presence of heptanol, cells in the isolated ICC network and in circular smooth muscle preparations showed spontaneous hyperpolarizing potential fluctuations at a frequency of four to six per second. These oscillations were abolished by current-induced hyperpolarization and TEA (30 mM) and are therefore likely due to spontaneously active K+ conductance.

Su1860 Extracellular Chloride (Cl−) Substitution Disrupts Electrical Slow Wave Activity but Has Small Effects on Membrane Potential in Mouse Jejunal Smooth Muscle

2015 ◽  
Vol 148 (4) ◽  
pp. S-536
Author(s):  
Siva Arumugam Saravanaperumal ◽  
Simon J. Gibbons ◽  
John Malysz ◽  
Joseph H. Szurszewski ◽  
Gianrico Farrugia
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Slow Wave ◽  
Wave Activity ◽  
Slow Wave Activity

Quantitative cellular description of gastric slow wave activity

2008 ◽  
Vol 294 (4) ◽  
pp. G989-G995 ◽  
Author(s):  
Alberto Corrias ◽  
Martin L. Buist
Keyword(s):  
Slow Wave ◽  
Interstitial Cells Of Cajal ◽  
Quantitative Description ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Good Correspondence ◽  
Gastric Slow Wave ◽  
Intracellular Ca ◽  
Cells Of Cajal

Interstitial cells of Cajal (ICC) are responsible for the spontaneous and omnipresent electrical activity in the stomach. A quantitative description of the intracellular processes whose coordinated activity is believed to generate electrical slow waves has been developed and is presented here. In line with recent experimental evidence, the model describes how the interplay between the mitochondria and the endoplasmic reticulum in cycling intracellular Ca2+ provides the primary regulatory signal for the initiation of the slow wave. The major ion channels that have been identified as influencing slow wave activity have been modeled according to data obtained from isolated ICC. The model has been validated by comparing the simulated profile of the slow waves with experimental recordings and shows good correspondence in terms of frequency, amplitude, and shape in both control and pharmacologically altered conditions.

Electromechanical effects of endothelin on ferret bronchial and tracheal smooth muscle

1990 ◽  
Vol 68 (1) ◽  
pp. 417-420 ◽  
Author(s):  
H. K. Lee ◽  
G. D. Leikauf ◽  
N. Sperelakis
Keyword(s):  
Smooth Muscle ◽  
Slow Wave ◽  
Smooth Muscles ◽  
Muscle Cells ◽  
Wave Activity ◽  
Slow Wave Activity ◽  
Resting Potential ◽  
Base Line ◽  
Dependent Manner ◽  
Bronchial Cells

The effects of endothelin (ET) on transmembrane potential and isometric force were studied in ferret bronchial and tracheal smooth muscles. At rest, the muscle cells were electrically and mechanically quiescent. The mean resting potential for the bronchial cells was -70 +/- 1 mV (n = 25 cells/8 ferrets), and that of the tracheal cells was -60 +/- 1 mV (n = 7 cells/2 ferrets). ET depolarized and contracted both types of muscle cells in a concentration-dependent manner. At 1 nM ET, the bronchial muscle cells were significantly depolarized with concomitant force generation. In contrast, greater than 30 nM ET was required for the tracheal muscle cells to respond. The bronchial cells were further depolarized by 10 and 100 nM ET with electrical slow-wave activity present. The calcium channel antagonist verapamil substantially inhibited the contractions produced by 100 nM ET and abolished the slow-wave activity without affecting the base-line depolarization. Pretreatment of the bronchial muscle with 30 microM indomethacin did not affect the ET-induced contraction. These results suggest that ET modulates airway smooth muscle tone by direct activation and/or depolarization-induced activation of sarcolemmal calcium channels.

Menstrual Respiratory Changes and Symptoms

1980 ◽  
Vol 136 (5) ◽  
pp. 492-497 ◽  
Author(s):  
J. Damas-Mora ◽  
Lisa Davies ◽  
Wendy Taylor ◽  
F. A. Jenner
Keyword(s):  
Carbon Dioxide ◽  
Menstrual Cycle ◽  
Slow Wave ◽  
Respiratory System ◽  
Normal Subjects ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Premenstrual Tension ◽  
Carbon Dioxide Sensitivity

SummaryThe duration of standardised overbreathing required to produce slow wave activity in the EEG during different phases of the menstrual cycle has been studied, and changes in carbon dioxide sensitivity of the respiratory system. Normal subjects developed slow waves more quickly and had more sensitive CO2 responses during the premenstrual/menstrual phases. This may be a factor contributing to premenstrual tension.

Electrical slow-wave activity from the circular layer of cat terminal antrum

1991 ◽  
Vol 261 (1) ◽  
pp. G78-G82
Author(s):  
L. M. Renzetti ◽  
M. B. Wang ◽  
J. P. Ryan
Keyword(s):  
Slow Wave ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Muscle Layer ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Plateau Phase ◽  
Circular Layer ◽  
Upstroke Velocity

Intracellular recording techniques were used to characterize the electrical slow-wave activity through the thickness of the circular muscle layer of the cat terminal antrum. Muscle strips were pinned out in cross section to the floor of a recording chamber perfused with Krebs buffer. Circular muscle cells from the myenteric to the submucosal border then were impaled with 20- to 40-M omega glass microelectrodes, and slow-wave activity was recorded. Slow waves from the myenteric side of the circular layer consisted of an upstroke depolarization, a prominent plateau phase, and a downstroke repolarization. Slow-wave characteristics for cells along the myenteric border were Em, -74.2 +/- 1.3 mV; duration, 5.3 +/- 0.5 s; upstroke amplitude, 29.4 +/- 3.4 mV; upstroke velocity, 0.20 +/- 0.03 V/s; and frequency, 5.8 +/- 0.5/min. Slow waves from muscle cells along the submucosal side of the preparation lacked a discernible plateau phase. Slow waves from submucosal border cells had the following characteristics: Em, -80.4 +/- 1.4 mV (P less than 0.01); duration, 3.5 +/- 0.4 s (P less than 0.01); upstroke amplitude, 44.0 +/- 2.4 mV (P less than 0.01); upstroke velocity, 0.56 +/- 0.06 V/s (P less than 0.01); and frequency, 4.2 +/- 0.4/min (P less than 0.05). Slow waves were not affected by 10(-7)M tetrodotoxin and 10(-6)M atropine or by removal of the longitudinal muscle layer. Slow-wave activity within each region was maintained after dissecting the circular layer into submucosal and myenteric segments. The results suggest that two distinct slow waves exist within the circular muscle layer of the cat terminal antrum.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Pilot Study of Propofol-induced Slow Waves as a Pharmacologic Test for Brain Dysfunction after Brain Injury

2017 ◽  
Vol 126 (1) ◽  
pp. 94-103 ◽  
Author(s):  
Jukka Kortelainen ◽  
Eero Väyrynen ◽  
Usko Huuskonen ◽  
Jouko Laurila ◽  
Juha Koskenkari ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Brain Injury ◽  
Pilot Study ◽  
Slow Wave ◽  
Low Frequency ◽  
Brain Dysfunction ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Neurologic Outcome

Abstract Background Slow waves (less than 1 Hz) are the most important electroencephalogram signatures of nonrapid eye movement sleep. While considered to have a substantial importance in, for example, providing conditions for single-cell rest and preventing long-term neural damage, a disturbance in this neurophysiologic phenomenon is a potential indicator of brain dysfunction. Methods Since, in healthy individuals, slow waves can be induced with anesthetics, the authors tested the possible association between hypoxic brain injury and slow-wave activity in comatose postcardiac arrest patients (n = 10) using controlled propofol exposure. The slow-wave activity was determined by calculating the low-frequency (less than 1 Hz) power of the electroencephalograms recorded approximately 48 h after cardiac arrest. To define the association between the slow waves and the potential brain injury, the patients’ neurologic recovery was then followed up for 6 months. Results In the patients with good neurologic outcome (n = 6), the low-frequency power of electroencephalogram representing the slow-wave activity was found to substantially increase (mean ± SD, 190 ± 83%) due to the administration of propofol. By contrast, the patients with poor neurologic outcome (n = 4) were unable to generate propofol-induced slow waves. Conclusions In this experimental pilot study, the comatose postcardiac arrest patients with poor neurologic outcome were unable to generate normal propofol-induced electroencephalographic slow-wave activity 48 h after cardiac arrest. The finding might offer potential for developing a pharmacologic test for prognostication of brain injury by measuring the electroencephalographic response to propofol.

scholarly journals Visual imagery and visual perception induce similar changes in occipital slow waves of sleep

2019 ◽  
Vol 121 (6) ◽  
pp. 2140-2152 ◽  
Author(s):  
Giulio Bernardi ◽  
Monica Betta ◽  
Jacinthe Cataldi ◽  
Andrea Leo ◽  
José Haba-Rubio ◽  
...  
Keyword(s):  
Visual Perception ◽  
Eye Movement ◽  
Slow Wave ◽  
Visual Imagery ◽  
Nrem Sleep ◽  
Wave Activity ◽  
Slow Waves ◽  
Slow Wave Activity ◽  
Short Term ◽  
Visual Areas

Previous studies have shown that regional slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep is modulated by prior experience and learning. Although this effect has been convincingly demonstrated for the sensorimotor domain, attempts to extend these findings to the visual system have provided mixed results. In this study we asked whether depriving subjects of external visual stimuli during daytime would lead to regional changes in slow waves during sleep and whether the degree of “internal visual stimulation” (spontaneous imagery) would influence such changes. In two 8-h sessions spaced 1 wk apart, 12 healthy volunteers either were blindfolded while listening to audiobooks or watched movies (control condition), after which their sleep was recorded with high-density EEG. We found that during NREM sleep, the number of small, local slow waves in the occipital cortex decreased after listening with blindfolding relative to movie watching in a way that depended on the degree of visual imagery subjects reported during blindfolding: subjects with low visual imagery showed a significant reduction of occipital sleep slow waves, whereas those who reported a high degree of visual imagery did not. We also found a positive relationship between the reliance on visual imagery during blindfolding and audiobook listening and the degree of correlation in sleep SWA between visual areas and language-related areas. These preliminary results demonstrate that short-term alterations in visual experience may trigger slow-wave changes in cortical visual areas. Furthermore, they suggest that plasticity-related EEG changes during sleep may reflect externally induced (“bottom up”) visual experiences, as well as internally generated (“top down”) processes.NEW & NOTEWORTHY Previous work has shown that slow-wave activity, a marker of sleep depth, is linked to neural plasticity in the sensorimotor cortex. We show that after short-term visual deprivation, subjects who reported little visual imagery had a reduced incidence of occipital slow waves. This effect was absent in subjects who reported strong spontaneous visual imagery. These findings suggest that visual imagery may “substitute” for visual perception and induce similar changes in non-rapid eye movement slow waves.

Electrical activity of intestine recorded with pressure electrode

1961 ◽  
Vol 201 (1) ◽  
pp. 209-212 ◽  
Author(s):  
Alex Bortoff
Keyword(s):  
Small Intestine ◽  
Membrane Potential ◽  
Electrical Activity ◽  
Slow Wave ◽  
Spike Activity ◽  
Intestinal Motility ◽  
Wave Activity ◽  
Slow Waves ◽  
Reverse Effect ◽  
Naturally Occurring

The effects of certain autonomic and metabolic drugs on the electrical activity of the small intestine have been investigated, using the pressure electrode. Epinephrine inhibits spike activity and increases the membrane potential, without apparently altering the size of the slow waves. Acetylcholine has the reverse effect. The hyperpolarization produced by epinephrine is followed by a gradual depolarization which exceeds that of the membrane prior to its addition; this is not accompanied by the reappearance of spike activity. Large concentrations of epinephrine produce a waxing and waning of the amplitude of the slow waves. During inhibition by dinitrophenol, both acetylcholine and epinephrine can initiate slow wave activity. An explanation of naturally occurring waxing and waning is suggested, together with a mechanism relating the activity of the two muscle layers during normal intestinal motility.

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