scholarly journals Effects of Removal of Na+ and Cl- on Spontaneous Electrical Activity, Slow Wave, in the Circular Muscle of the Guinea-Pig Gastric Antrum.

2000 ◽  
Vol 50 (5) ◽  
pp. 469-477 ◽  
Author(s):  
Tadao Tomita ◽  
Tadayoshi Hata
Keyword(s):  
Guinea Pig ◽  
Electrical Activity ◽  
Slow Wave ◽  
Circular Muscle ◽  
Gastric Antrum ◽  
Spontaneous Electrical Activity

Voltage sensitivity of slow wave frequency in isolated circular muscle strips from guinea pig gastric antrum

1999 ◽  
Vol 276 (2) ◽  
pp. G518-G528 ◽  
Author(s):  
S.-M. Huang ◽  
S. Nakayama ◽  
S. Iino ◽  
T. Tomita
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Slow Wave ◽  
Circular Muscle ◽  
Gastric Antrum ◽  
Slow Waves ◽  
Wave Frequency ◽  
Voltage Sensitivity ◽  
Dependent Manner ◽  
Circular Smooth Muscle

In circular muscle preparations isolated from the guinea pig gastric antrum, regular spontaneous electrical activity (slow waves) was recorded. Under normal conditions (6 mM K+), the frequency and shape of the slow waves were similar to those observed in ordinary stomach smooth muscle preparations. When the resting membrane potential was hyperpolarized and depolarized by changing the extracellular K+ concentration (2–18 mM), the frequency of slow waves decreased and increased, respectively. Application of cromakalim hyperpolarized the cell membrane and reduced the frequency of slow waves in a dose-dependent manner. Cromakalim (3 μM) hyperpolarized the membrane, and slow waves ceased in most preparations. In the presence of cromakalim, subsequent increases in the extracellular K+ concentration restored the frequency of slow waves accompanied by depolarization. Also, glibenclamide completely antagonized this effect of cromakalim. In smooth muscle strips containing both circular and longitudinal muscle layers, such changes in the slow wave frequency were not observed. It was concluded that the maneuver of isolating circular smooth muscle altered the voltage dependence of the slow wave frequency.

scholarly journals Effects of cromakalim on the electrical slow wave in the circular muscle of guinea-pig gastric antrum

1993 ◽  
Vol 109 (4) ◽  
pp. 1097-1100 ◽  
Author(s):  
N. Katayama ◽  
S.-M. Huang ◽  
T. Tomita ◽  
Alison F. Brading
Keyword(s):  
Guinea Pig ◽  
Slow Wave ◽  
Circular Muscle ◽  
Gastric Antrum

Disinhibition of circular muscle slow waves by piroxicam in isolated guinea-pig gastric antrum and duodenum

2001 ◽  
Vol 120 (5) ◽  
pp. A534
Author(s):  
Shi Yong Yuan ◽  
Marcello Costa ◽  
Simon J.H. Brookes
Keyword(s):  
Guinea Pig ◽  
Circular Muscle ◽  
Gastric Antrum ◽  
Slow Waves

Mechanisms underlying nutrient-induced segmentation in isolated guinea pig small intestine

2007 ◽  
Vol 292 (4) ◽  
pp. G1162-G1172 ◽  
Author(s):  
R. M. Gwynne ◽  
J. C. Bornstein
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Motor Neurons ◽  
Slow Wave ◽  
Neural Circuit ◽  
Circular Muscle ◽  
Decanoic Acid ◽  
Slow Waves ◽  
Longitudinal Position

Mechanisms underlying nutrient-induced segmentation within the gut are not well understood. We have shown that decanoic acid and some amino acids induce neurally dependent segmentation in guinea pig small intestine in vitro. This study examined the neural mechanisms underlying segmentation in the circular muscle and whether the timing of segmentation contractions also depends on slow waves. Decanoic acid (1 mM) was infused into the lumen of guinea pig duodenum and jejunum. Video imaging was used to monitor intestinal diameter as a function of both longitudinal position and time. Circular muscle electrical activity was recorded by using suction electrodes. Recordings from sites of segmenting contractions showed they are always associated with excitatory junction potentials leading to action potentials. Recordings from sites oral and anal to segmenting contractions revealed inhibitory junction potentials that were time locked to those contractions. Slow waves were never observed underlying segmenting contractions. In paralyzed preparations, intracellular recording revealed that slow-wave frequency was highly consistent at 19.5 (SD 1.4) cycles per minute (c/min) in duodenum and 16.6 (SD 1.1) c/min in jejunum. By contrast, the frequencies of segmenting contractions varied widely (duodenum: 3.6–28.8 c/min, median 10.8 c/min; jejunum: 3.0–27.0 c/min, median 7.8 c/min) and sometimes exceeded slow-wave frequencies for that region. Thus nutrient-induced segmentation contractions in guinea pig small intestine do not depend on slow-wave activity. Rather they result from a neural circuit producing rhythmic localized activity in excitatory motor neurons, while simultaneously activating surrounding inhibitory motor neurons.

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