Cellular effects of gastric electrical stimulation on antral smooth muscle cells in rats

2010 ◽  
Vol 298 (6) ◽  
pp. R1580-R1587 ◽  
Author(s):  
Shiying Li ◽  
Jiande D. Z. Chen
Keyword(s):  
Smooth Muscle ◽  
Electrical Stimulation ◽  
Cell Membrane ◽  
Smooth Muscle Cells ◽  
Action Potentials ◽  
Pulse Train ◽  
Pulse Width ◽  
Pulse Frequency ◽  
Membrane Potentials ◽  
Cellular Effects

The cellular effects of gastric electrical stimulation (GES), which has recently been introduced as a potential therapy for the treatment of gastroparesis and obesity, were investigated in rat antrum smooth muscle cells (SMCs). Effects on cell membrane potentials of single electrical current pulses (pulse width from 0.1 ms to 200 ms) and 2-s pulse train stimuli with different pulse widths (0.1–4 ms), different frequencies (20–200 Hz), and different intensities were studied: 1) the stimulus amplitude had an exponential relationship to the pulse width from 2 ms to 200 ms, along with a rapidly rising strength-duration curve at pulse widths less than 5 ms, and a relatively flat curve at pulse widths greater than 50 ms; 2) when the pulse frequency was at 80 Hz or above, pulse train electrical stimulation, with a pulse width of 2 ms or above but not ≤1 ms, was able to depolarize cell membrane potentials to above −30 mV and/or generate action potentials. Electrical stimulation with a single long pulse and a width of 50 ms or greater is effective in depolarizing cell membrane potentials of SMCs with low amplitude. Pulse train electrical stimulation with a pulse width of ≤1 ms fails to generate action potentials in SMCs, whereas pulse train electrical stimulation with a pulse width of 2–4 ms and a sufficiently high pulse frequency is able to generate action potentials. These cellular findings may be useful in optimizing stimulation parameters of GES.

scholarly journals Effects of electrical stimulation on isolated rodent gastric smooth muscle cells evaluated via a joint computational simulation and experimental approach

2009 ◽  
Vol 297 (4) ◽  
pp. G672-G680 ◽  
Author(s):  
P. Du ◽  
S. Li ◽  
G. O'Grady ◽  
L. K. Cheng ◽  
A. J. Pullan ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Electrical Stimulation ◽  
Pulse Train ◽  
Pulse Width ◽  
Computational Simulation ◽  
Minimum Energy ◽  
Experimental Studies ◽  
Single Pulse ◽  
Plateau Phase ◽  
Wide Range

Gastric electrical stimulation (GES) involves the delivery of electrical impulses to the stomach for therapeutic purposes. New GES protocols are needed that are optimized for improved motility outcomes and energy efficiency. In this study, a biophysically based smooth muscle cell (SMC) model was modified on the basis of experimental data and employed in conjunction with experimental studies to define the effects of a large range of GES protocols on individual SMCs. For the validation studies, rat gastric SMCs were isolated and subjected to patch-clamp analysis during stimulation. Experimental results were in satisfactory agreement with simulation results. The results define the effects of a wide range of GES parameters (pulse width, amplitude, and pulse-train frequency) on isolated SMCs. The minimum pulse width required to invoke a supramechanical threshold response from SMCs (defined at −30 mV) was 65 ms (at 250-pA amplitude). The minimum amplitude required to invoke this threshold was 75 pA (at 1,000-ms pulse width). The amplitude of the invoked response beyond this threshold was proportional to the stimulation amplitude. A high-frequency train of stimuli (40 Hz; 10 ms, 150 pA) could invoke and maintain the SMC plateau phase while requiring 60% less power and accruing ∼30% less intracellular Ca2+ concentration during the plateau phase than a comparable single-pulse protocol could in a demonstrated example. Validated computational simulations are an effective strategy for efficiently identifying effective minimum-energy GES protocols, and pulse-train protocols may also help to reduce the power consumption of future GES devices.

Effects of Histamine and Endothelin-1 on Membrane Potentials and Ion Currents in Bovine Tracheal Smooth-Muscle Cells

1998 ◽  
Vol 19 (5) ◽  
pp. 805-811 ◽  
Author(s):  
Masayuki Nara ◽  
Tsukasa Sasaki ◽  
Sanae Shimura ◽  
Takako Oshiro ◽  
Toshiya Irokawa ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Membrane Potentials ◽  
Tracheal Smooth Muscle ◽  
Ion Currents ◽  
Endothelin 1

Effects of prostaglandin F2α on membrane currents in rabbit middle cerebral arterial smooth muscle cells

2003 ◽  
Vol 284 (3) ◽  
pp. H1018-H1027 ◽  
Author(s):  
Nari Kim ◽  
Jin Han ◽  
Euiyong Kim
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscles ◽  
Muscle Cells ◽  
Membrane Potentials ◽  
Delayed Rectifier ◽  
Direct Effects ◽  
Patch Clamp Technique ◽  
Arterial Smooth Muscle ◽  
Arterial Smooth Muscle Cells

Although PGF2αaffects contractility of vascular smooth muscles, no studies to date have addressed the electrophysiological mechanism of this effect. The purpose of our investigation was to examine the direct effects of PGF2α on membrane potentials, Ca2+-activated K+ (KCa) channels, delayed rectifier K+ (KV) channels, and L-type Ca2+channels with the patch-clamp technique in single rabbit middle cerebral arterial smooth muscle cells (SMCs). PGF2αsignificantly hyperpolarized membrane potentials and increased the amplitudes of total K+ currents. PGF2αincreased open-state probability but had little effect on the open and closed kinetics of KCa channels. PGF2αincreased the amplitudes of KV currents with a leftward shift of the activation and inactivation curves and a decrease in the activation time constant. PGF2α decreased the amplitudes of L-type Ca2+ currents without any significant change in threshold or apparent reversal potentials. This study provides the first finding that the direct effects of PGF2α on middle cerebral arterial SMCs, at least in part, could attenuate vasoconstriction.

Cytosolic Calcium Oscillations in Smooth Muscle Cells

Physiology ◽  
2000 ◽  
Vol 15 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Jean-Pierre Savineau ◽  
Roger Marthan
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Smooth Muscle Cells ◽  
Inositol Trisphosphate ◽  
Muscle Cells ◽  
Cytosolic Calcium ◽  
Calcium Oscillations ◽  
Membrane Receptors ◽  
Cell Membrane Potential

In a variety of smooth muscle cells, agonists activating membrane receptors induce oscillations in the cytoplasmic Ca2+ concentration via an inositol trisphosphate-activated mechanism. Ca2+ oscillations participate in the control of cell membrane potential and the tone of smooth muscle. There is evidence that alterations in Ca2+ oscillations modulate smooth muscle responsiveness.

Cell membrane stretch activates intermediate-conductance Ca2+-activated K+ channels in arterial smooth muscle cells

2010 ◽  
Vol 26 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Yasunobu Hayabuchi ◽  
Yutaka Nakaya ◽  
Kazuaki Mawatari ◽  
Miki Inoue ◽  
Miho Sakata ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Cell Membrane ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Arterial Smooth Muscle ◽  
K Channels ◽  
Membrane Stretch ◽  
Arterial Smooth Muscle Cells

scholarly journals FINE STRUCTURE OF SMOOTH MUSCLE CELLS GROWN IN TISSUE CULTURE

1971 ◽  
Vol 49 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Gordon R. Campbell ◽  
Yasuo Uehara ◽  
Gerda Mark ◽  
Geoffrey Burnstock
Keyword(s):  
Electron Microscopy ◽  
Smooth Muscle ◽  
Fine Structure ◽  
Cell Membrane ◽  
Smooth Muscle Cells ◽  
Phase Contrast ◽  
Muscle Cells ◽  
Different Types ◽  
Membrane Infoldings

The fine structure of smooth muscle cells of the embryo chicken gizzard cultured in monolayer was studied by phase-contrast optics and electron microscopy. The smooth muscle cells were irregular in shape, but tended to be elongate. The nucleus usually contained prominent nucleoli and was large in relation to the cell body. When fixed with glutaraldehyde, three different types of filaments were noted in the cytoplasm: thick (150–250 A in diameter) and thin (30–80 A in diameter) myofilaments, many of which were arranged in small bundles throughout the cytoplasm and which were usually associated with dark bodies; and filaments with a diameter of 80–110 A which were randomly orientated and are not regarded as myofilaments. Some of the aggregated ribosomes were helically arranged. Mitochondria, Golgi apparatus, and dilated rough endoplasmic reticulum were prominent. In contrast to in vivo muscle cells, micropinocytotic vesicles along the cell membrane were rare and dense areas were usually confined to cell membrane infoldings. These cells are compared to in vivo embryonic smooth muscle and adult muscle after treatment with estrogen. Monolayers of cultured smooth muscle will be of particular value in relating ultrastructural features to functional observations on the same cells.

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