Intracellular electrical activity of canine and human gastric smooth muscle.

El-Sharkawy, T. Y.; Morgan, Kathleen G.; Szurszewski, Joseph H.

doi:10.1113/jphysiol.1978.sp012345

Cited by 157 publications

(130 citation statements)

References 15 publications

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“…In sixty-one anaesthetized dogs of either sex (10-22 kg), the entire stomach was removed (El-Sharkawy et al 1978) and a piece of the external muscularis was taken either from the fundus (the area cephalad to the oesophagogastric junction) or the antrum. Strips (2 x 6 mm) of the fundus were dissected from the centre of the fundus taking care to exclude fibres of sling muscle (Torgessen, 1942).…”

Section: Methodsmentioning

confidence: 99%

“…Muscle strips with the serosal surface uppermost were pinned to the floor of a Sylgard-coated bath. The technique for dissecting circular antral strip has been described previously (El-Sharkawy et al 1978). For simultaneous measurement of tension and intracellular potentials, a 4 x 2 mm flap was left unpinned and attached to a force transducer.…”

Section: Methodsmentioning

confidence: 99%

“…By 'receptive relaxation' (Cannon & Lieb, 1911) the fundus acts as a reservoir during ingestion of food (Code & Carlson, 1968); but the physiological basis for such activity in the fundus is unknown. Unlike the corpus and antrum of the stomach, the fundus shows no spontaneous phasic contractions and no spontaneous electrical activity (El-Sharkawy, Morgan & Szurszewski, 1978). The gastric action potential which originates in the orad corpus, does not propagate into the fundus in vivo (Kelly, Code & Elveback, 1959).…”

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confidence: 99%

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The electrical basis for contraction and relaxation in canine fundal smooth muscle

Morgan¹,

Muir

Szurszewski³

1981

The Journal of Physiology

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SUMMARY1. Mechanical and intracellular electrical activities were recorded simultaneously from canine fundal and antral smooth muscle preparations.2. Most fundal preparations displayed no spontaneous electrical or mechanical activity. The tissue had a space constant of 1.5 mm and a time constant of 189 msec and showed outward rectification in response to depolarizing current. 3. Transmural nerve stimulation offundal preparations demonstrated the presence ofcholinergic excitatory and non-cholinergic, non-adrenergic inhibitory neural inputs to the tissue. The cholinergic nerve response consisted ofa small, graded depolarization accompanied by a slow graded contraction; the inhibitory nerve response consisted of a graded hyperpolarization accompanied by a slow relaxation.4. The excitatory fundal nerve response was abolished or greatly diminished by D600 and Mn2+. D600 and Mn2+ also decreased basal tone. The inhibitory nerve response was unaffected by either agent. 5. The excitatory nerve response in the fundus was contrasted with the excitatory nerve response in the antrum. In the fundus, stimulation of cholinergic motor nerves produced a depolarization which always produced a contraction. In the antrum, stimulation of cholinergic motor nerves between action potentials produced graded depolarizations of antral cells; however, there were no associated contractions. Stimulation of cholinergic motor nerves during spontaneous action potentials increased the amplitude and duration of the plateau phase of the action potential; this was associated with an augmentation of the spontaneous contractions.6. Voltage-tension curves were determined for antral and fundal preparations using K+ depolarization as a means of controlling membrane potential. Antral preparations displayed a voltage threshold for contraction at a membrane potential approximately 30 mV positive to the resting potential. In contrast, fundal resting potentials were at or more positive than their voltage thresholds.7. These differences in electromechanical coupling provide an explanation for the marked differences in the responses of fundal and antral smooth muscles to nerve stimulation and account for their physiologic function in vivo.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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The electrical basis for contraction and relaxation in canine fundal smooth muscle

Morgan¹,

Muir

Szurszewski³

1981

The Journal of Physiology

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“…In the dog stomach, D-600 blocks the slow potential change but not the spike potential (ElSharkawy et al, 1978); this observation is in contrast to that seen in the guinea-pig stomach. In both cases, spike potentials and slow potential changes are abolished in Ca-free solution (Ohba et al, 1977;El-Sharkawy et al, 1978), suggesting that the mechanism responsible for the generation of these electrical responses are different in the various species.…”

Section: Discussionmentioning

confidence: 98%

Effects of diltiazem on electrical responses evoked spontaneously or by electrical stimulation in the antrum smooth muscle cells of the guinea‐pig stomach

Ishikawa

Komori

Nagao

et al. 1985

British J Pharmacology

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In circular smooth muscle cells of the guinea‐pig stomach (antrum), diltiazem (10−6 − 10−5 M) blocked the overshooting spike potential generated either spontaneously or by electrical stimulation in the presence of 2 mM tetraethylammonium chloride, but did not block the slow wave and the abortive spike potential. The membrane was depolarized by high concentrations of diltiazem (more than 3 × 10−6 M), and this depolarization was associated with an increase in the membrane resistance. The interval between slow waves was shortened to about 0.90 times the control (14.7 s) by 10−5 M diltiazem. Transmural nerve stimulation evoked an inhibitory junction potential (i.j.p.) and enhanced the subsequently generated slow wave. Tetrodotoxin (3 × 10−7 M) blocked both responses but atropine (10−6 M) blocked only the latter. Diltiazem (more than 10−6 M) increased the amplitude of the i.j.p. and depressed the enhancement of the slow wave produced by transmural nerve stimulation, presumably due to depolarization of the membrane. The latency for the i.j.p. remained the same in the presence of diltiazem (10−5 M). It is concluded that in the guinea‐pig stomach, diltiazem blocks Ca‐influx during the generation of the overshooting spike potential, but not the Ca‐influx related to generation of the abortive spike potential or the slow wave. The cholinergic excitatory and the non‐adrenergic, non‐cholinergic inhibitory transmission may not be much affected by diltiazem.

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“…An increase in pacemaker frequency will lead to an increase in the frequency of peristaltic contractions when the stomach is maximally activated. The human stomach pacemaker activity is myogenic in origin [17], but can be influenced by the parasympathetic and sympathetic nervous system to increase or decrease its duration and frequency. The present study does not allow us to make conclusions about effect of the training on autonomic innervation of the gastric pacemaker cells.…”

Section: Discussionmentioning

confidence: 99%

Noninvasive measurements to evaluate the effects of military training on the human autonomic nervous system

et al. 2014

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Background: Chinese university freshmen receive 4-weeks military training that involved moderate to intense physical exercise. Studies have demonstrated heterogeneous effects of exercise on the autonomic nervous system. Objective: To evaluate the effects of training on the autonomic nervous system noninvasively using electrogastrograms, heart rate variability (HRV), pulse rate, and the sympathetic skin response (SSR). Methods: Twenty freshmen received all assessments in the fasting state and after a standard meal: (1) one week before the training, (2) at the end of the second week of the training, and (3) one week after the training. Results: (1) The training had a significant effect on meal-induced gastric pacemaker activity. Before the training, a standard meal did not increase the dominant frequency of gastric slow waves, but the frequency increased during and after the training; (2) The preprandial high frequency (HF), low frequency (LF), and very low frequency (VLF) components of heart rate variability decreased significantly after the training. The ratio of the LF and HF (LF/HF) of the heart rate variability (HRV) did not significantly change after a meal or training condition. The basal pulse rate did not change. The latencies of the sympathetic skin response (SSR), as measured in the arm muscle, increased in response to the training. Conclusion: Military training affects meal-induced changes in gastric pacemaker activity, causes a marked reduction of the vagal tone to the heart with maintenance of the vagal-sympathetic balance, and its effects on SSR may reflect a reduction in sympathetic tone.

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Intracellular electrical activity of canine and human gastric smooth muscle.

Cited by 157 publications

References 15 publications

The electrical basis for contraction and relaxation in canine fundal smooth muscle

The electrical basis for contraction and relaxation in canine fundal smooth muscle

Effects of diltiazem on electrical responses evoked spontaneously or by electrical stimulation in the antrum smooth muscle cells of the guinea‐pig stomach

Noninvasive measurements to evaluate the effects of military training on the human autonomic nervous system

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