• Korean Journal of Veterinary Research
• /
• v.60 no.2
• /
• pp.55-59
• /
• 2020

This study was purposed to make the referenced range of stomach antral contraction strain in 50 dogs using 2-dimensional speckle tracking. In addition, the strain results were compared among body condition scores to reveal the correlations of obesity among the subjects of the study. Finally, the medetomidine group that was comprised of 10 dogs was compared with the normal group to identify the medetomidine pharmacologic effect in the stomach antral contraction. Clinically healthy 50 dogs were recruited for the study. In an ultrasonographic examination, the stomach antrum region was scanned, and at least one cycle of antral contraction was recorded. The peak strain of antral contraction in healthy dogs was 58.2 ± 20.47% (mean ± SD). The obesity group showed a high strain result and there were significant correlations between the body condition score (BCS) 2, BCS 3 groups and BCS 8 group. The medetomidine group revealed a low strain result and was significantly correlated with normal group. Two-dimensional speckle tracking was useful to the evaluation of stomach motility disorders.

• The Korean Journal of Physiology
• /
• v.25 no.2
• /
• pp.133-146
• /
• 1991

In order to elucidate systematically the effects of serotonin on gastric motility of guinea-pig, the contractile and electrical responses to serotonin were recorded using four kinds of muscle strips prepared from antral circular, antral longitudinal, fundic circular, and fundic longitudinal muscles. Experiments were performed using various methods including isometric contraction recording, transmural electrical field stimulation, junction potential recording, intracellular microelectrode technique, and partition stimulation method. The results were as follows: 1) The effect of serotonin on spontaneous contractions was inhibitory in the circular muscle strips of the antrum and fundus, while it was excitatory in the longitudinal muscle strips of the antrum and fundus. Serotonin changed mainly phasic contractions of both the circular and longitudinal muscle strips in the antrum, while it changed mainly tonic contractions of both the circular and longitudinal muscle strips in the fundus. 2) On the contractions induced by transmural nerve stimulation, serotonin decreased the amplitude in the circular muscle strips of the antrum, but it increased them in the other three groups of muscle strips(antral longitudinal, fundic circular, and fundic longitudinal). 3) On the contractions induced by direct muscle stimulation, serotonin decreased the amplitude in the circular muscle strips of the antrum and fundus. 4) In the fundic circular muscle strips serotonin potentiated excitatory junction potentials (EJPs), and in the antral circular muscle strips it evoked EJPs after inhibitory junction potentials(IJPS). 5) In the antral circular muscle strips serotonin did not affect the slow wave even at the disappearance of spontaneous contractions. On the contrary it increased the amplitude of the slow wave, when the spike component was potentiated and the second component was inhibited. 6) In the antral circular muscle strips the membrane potential was slightly hyperpolarized, but the membrane resistance was not changed. From the above results following conclusions could be made. 1) Serotonin inhibits spontaneous contractions of the circular muscle layer and it increases those of the longitudinal one, irrespective of the gastric region. 2) In the guinea-pig stomach there exists a serotoninergic facilitatory neuromodulation system which exerts its effect on cholinergically mediated contraction. 3) The excitation-contraction decoupling was observed in the effect of serotonin.

• The Journal of Internal Korean Medicine
• /
• v.31 no.4
• /
• pp.857-869
• /
• 2010

Objectives : The aim of this study was to evaluate whether rats with non-obstructive antral dilation could be a useful tool resembling functional dyspeptic patients. We also investigated the effect of Bojoongikki-tang (BJ), and Youngkaechulgam-tang (YK) in antral dilated rats. Methods : Non-obstructive antral dilation was performed by first wrapping a non-absorbable rubber ring (D:6mm, W:4mm, T:1mm) around the 1st portion of the duodenum causing pyloric obstruction (PO). After 12 weeks, except for some PO group rats used for the control, the rubber ring was removed by performing another operation. The antral dilated rats (AD) were then divided into three groups, a non-treatment group (AD-NT), and two herbal medicine groups each given an extract solution containing 125 mg/kg of Youngkaechulgam-tang (AD-YK) or Bojoongikki-tang (AD-BJ) for 4 weeks. Then gastric contractility was evaluated by bowel sound measurement, and afterwards the changes of the weight, and morphologic changes of the stomach were evaluated for each group including the normal intact group (NI). Results : Loss of weight and enlargement of the stomach surface area was seen in the PO group. Decrease of gastric motility index was observed in the AD-NT group, while the increased surface area of the stomach was not significantly different from the PO group. Youngkaechulgam-tang seemed to increase gastric contraction, whereas Bojoongikki-tang showed no effect. Weight gain of rats was observed in both the AD-YK and AD-BJ groups, but there seemed to be no change of the dilated stomach surface area. Conclusions : The non-obstructive antral dilated rat seems to be an experimental pathologic model that reflects the gastric dysmotility similar to functional dyspeptic patients with antral dilation. Therefore patients with dysmotility-like dyspepsia with antral function disorders should be treated efficiently. As Youngkaechulgam-tang is shown to increase both gastric contraction and weight in antral dilated rats, it may be used for treating functional dyspepsia. However, Bojoongikki-tang should be used with caution in patients with gastric dysmotility.

• The Korean Journal of Physiology
• /
• v.14 no.2
• /
• pp.21-28
• /
• 1980

In order to investigate the effect of cholinergic substance on the electrical and the mechanical activities of the stomach muscle, 10 isolated cat stomachs were studied. At various sites of a stomach muscle preparation, the electrical activity was monopolarly recorded by using capillary electrodes containing chlorided silver wires, and the isometric contractile activity was recorded simultaneously at the terminal portion of the antrum in Krebs solution$(36^{\circ}C)$ which was aerated with a gas mixture consisting of 95% $O_2$ and 5% $CO_2$. The recording of these activities were performed before (control period) and after acetylcholine$(10^{-5}M)$ and atropine $(10^{-6}M)$ administrations serially. Following results were obtained: 1) The mean frequency of the slow wave was $4.36{\pm}0.22\;cycles/min$ at all the various sites of the cat stomach. The slow wave was propagated caudad in sequence and its velosity of propagation increased as the slow wave approached the pylorus in normal Krebs solution. 2) After acetylcholine administration, the frequency of the slow wave increased transiently and the increase of slow wave frequency was followed by the isometric contraction of antral muscle in association with the second potential which succeeded the slow wave. 3) By atropine administration, the stimulatory effect of acetylcholine on the antral muscle contraction was abolished completely, and the frequency of the slow wave decreased significantly compared with that of the control period, which tendency was more prominent in the antrum. The above results suggest that the transient increase in the frequency of gastric slow wave by acetylcholine may have some influence upon the contraction mechanism of the cat antral muscle.

• The Korean Journal of Physiology
• /
• v.26 no.2
• /
• pp.129-136
• /
• 1992

The effects of $Cd^{2+}$ on spontaneous contraction, and the contractures induced by $0mM\;Na^+,\;60mM\;K^+\;and\;10^{-6}\;M$ acetylcholine, 1mM caffeine were studied in order to elucidate diverse actions of $Cd^{2+}$ on the $Ca^{2+}$ mobilization related with contractility in the antral circular muscle of guinea pig stomach. $Cd^{2+}$ inhibited the spontaneous contraction in a does dependent manner $(10^{-6}\;M\;10^{-4}\;M).\;Cd^{2+}\;(3{\times}10^{-5}M)$ suppressed 60 mM $K^+$ induced contracture composed or a phasic and a tonic response and the increased tonic response by the increased external $Ca^{2+}$ concentration. $Cd^{2+}$ also suppressed acetylcholine induced contracture composed of repetitive phasic and a tonic component and the increased tonic response by the increased external $Ca^{2+}$ concentration. Caffeine in the concentration of 1mM evoked contracture but $Cd^{2+}$ suppressed the contracture. $Cd^{2+}$ suppressed the amplitude of the $Na^+$ tee contracture dose dependently and the amplitude of $Na^+$ free contracture almost decreased to 20% of control amplitude in the concentration of $10^{-4}\;M\;Cd^{2+}$. From the above results, it is suggested that $Cd^{2+}$ may inhibit not only $Ca^{2+}$ influx via voltage sensitive, receptor operated $Ca^{2+}$ channel and Na/ca exchange but also intracellular $Ca^{2+}$ release from the sarcoplasmic reticulum in the antral circular muscle of guinea pig stomach.

• The Korean Journal of Physiology
• /
• v.28 no.1
• /
• pp.51-59
• /
• 1994

This study was carried out to elucidate the excitatory mechanisms of Substance P in the antral circular muscle, using isometric contraction recording, conventional microelectrode method and whole-cell patch clamp technique. Substance P produced tonic and phasic contractions in a dose-dependent manner and depolarized membrane potential with increased amplitude of slow waves in muscle strips. Voltage-dependent $Ca^{2+}$ currents were increased by the application of Substance P from a holding potential of -60mV to 50mV in 10mV steps and this effect was blocked by the addition of an antagonist. Also Substance P increased transient and spontaneous oscillatory $K^+$ outward currents. The enhanced outward currents were abolished by apamin in dispersed single cells. These results suggest that the depolarization of membrane potential by Substance P activates voltage-dependent $Ca^{2+}$ channels, which represents an excitatory response in the antral circular muscle and led to an increase in $Ca^{2+}\;activated\;K^+\;currents$.

• Korean Journal of Veterinary Research
• /
• v.40 no.4
• /
• pp.691-699
• /
• 2000

We investigated the effects of nitric oxide (NO) donors, S-nitroso-L-cysteine (Cys-NO) and 3-morpholinosydnonimine hydrochloride (SIN-1), on the contractile and electrical activity of the circular muscle of guinea pig gastric antrum by using intracellular microelectrode technique. The gastric antral circular muscle showed spontaneous phasic contraction and slow wave of membrane potential. Cys-NO ($0.001{\sim}10{\mu}M$) and SIN-1 ($0.001{\sim}100{\mu}M$) reduced not only the tonic and phasic contraction but also the amplitude of slow wave in a concentration dependent manner. NO donors were more potent to inhibit phasic contraction than to do slow wave. These inhibitory effects of NO donors were mimicked by the membrane permeable guanosine-3',5'-cyclic monophosphate (cGMP) analogue, 8-bromo-cyclic GMP (8-br-cGMP, $10{\sim}300{\mu}M$). The inhibitory effects of SIN-1 and Cys-NO were antagonized by the guanylate cyclase inhibitor, 1H[ [1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, $10{\mu}M$). These results suggest that the inhibitory effects of NO donors on the mechanical and electrical activity is mainly mediated by cGMP pathway.

• The Korean Journal of Physiology
• /
• v.25 no.2
• /
• pp.147-158
• /
• 1991

The effects of noradrenaline on the spontaneous contraction recorded from a strip of mucosa-free antral circular muscle were studied in the guinea-pig stomach, and the changes in slow waves and membrane resistance were analyzed in order to elucidate the mechanism for the excitatory response to noradrenaline. Electrical responses of circular muscle cells were recorded using glass microelectrodes filled with 3 M KCI. Electrotonic potentials were produced to estimate membrane resistance by the partition stimulating method. All experiments were performed in tris-buffered Tyrode solution which was aerated with 100% $O_2$ and kept at $35^{\circ}C$. The results obtained were as follows: 1) The spontaneous contractions were potentiated dose-dependently by the application of noradrenaline. 2) Through the experiments using adrenoceptor-blockers, the strong excitatory effect via $[\alpha}-adrenoceptors$ and the weak inhibitory efffect via ${\beta}-adrenoceptors$ were noted. 3) Noradrenaline produced hyperpolarization of membrane potential, and increases in the amplitude and the maximum rate of rise of slow waves. 4) In the presence of apamin, Ca-dependent K channel blocker, the characteristic hyperpolarization was not developed. However, the excitatory effect of noradrenaline on spontaneous contraction remained. 5) Membrane resistance was reduced during the hyperpolarized state by the application of noradrenaline, and the change of membrane resistance and the hyperpolarized state were completely abolished by apamin. From the above results, following conclusions could be made: Excitatory responses to noradrenaline result from the dominant ${\alpha}-excitatory$, and the weak ${\beta}-inhibitory$ action of noradrenaline. Hyperpolarization of membrane potential by noradrenaline is due to the activation of Ca-dependent K channel.

• Korean Journal of Veterinary Research
• /
• v.41 no.4
• /
• pp.485-495
• /
• 2001

It was investigated whether $Ca^{2+}$ and $K^+$ channels were involved in the inhibitory action of nitric oxide (NO) on the contractile and slow wave activity of guinea pig gastric antral circular muscle. The gastric antral circular muscle showed spontaneous phasic contraction and slow wave. NO donors, 3-morpholinosydnonimine hydrochloride (SIN-1, $0.01{\sim}100{\mu}M$) and S-nitroso-L-cysteine (CysNO, $0.001{\sim}10{\mu}M$), reduced not only the amplitude of phasic contraction but also that of slow wave in a concentration-dependent manner. Both the perfusion of $Ca^{2+}$-free solution and the administration of $Ni^{2+}$, a nonselective $Ca^{2+}$ channel blocker, reduced the phasic contraction as well as the amplitude and frequency of the slow wave. The effects of these treatments were similar to those of NO donors. Nifedipine ($10{\mu}M$), a specific L-type $Ca^{2+}$ channel blocker, abolished the phasic contraction and remarkably reduced the plateau of slow wave but had no profound effect on the upstroke of slow wave. In the whole-cell patch clamp mode, CysNO shifted the steady-state activation curve for L-type $Ca^{2+}$ current to the right and the steady-state inactivation curve to the left. Pretreatment of various $K^+$ channel blockers such as tetraethylammonium (1 mM), 4-aminopyridine (0.5 mM), glibenclamide (10 mM), apamin ($0.1{\mu}M$), and iberiotoxin ($0.1{\mu}M$) did not affect the inhibitory action of SIN-1. These results suggest that NO donors suppress mechanical and electrical activity of guinea pig gastric antral circular muscle by inhibition of L-type $Ca^{2+}$ channel rather than by activation of $K^+$ channels.

• The Korean Journal of Physiology
• /
• v.23 no.2
• /
• pp.263-275
• /
• 1989

Mechanical contractions and electrical activities of the fundic longitudinal and antral circular muscle fibers were investigated in order to elucidate topical differences of gastric motility. K-induced contracture was produced by exposure of muscle strips to high K Tyrode solution. Membrane potential and mechanical contraction were simultaneously recorded by conventional glass microelectrode method and single sucrose-gap technique. All experiments were performed in tris-buffered Tyrode solution which was aerated with $100%\;O_2\;and\;kept\;35^{\circ}C$. The results obtained were as follows: 1) The resting membrane potential of circular muscle cells in the antral region was about 10 mV more negative than that in the fundic region. 2) The membrane potentials decreased almost linearly as the extracellular KCI concentration was increased both in antral circular muscle cells and in fundic longitudinal muscle cells. 3) The thresholdal K concentration of K-contracture was 15 mM (membrane potential, -48 mV) for the antral circular muscle strip and 20 mM for the fundic longitudinal muscle cells. 4) The ratio of membrane permeability coefficient for $Na^+\;and\;K^+,\;P_{Na}/P_K\;({\alpha})$ was 0.065 for antral circular muscle cells and was 0.108 for fundic longitudinal muscle cells. 5) K-contracture of antral and fundic smooth muscle strips showed the contracture composed of phasic and tonic components. The amplitude of the phasic component increased sigmoidally in a dose-dependent manner, whereas that of the tonic component was maximal at a concentration of 40 mM KCI and at the concentrations above or below 40 mM KCI the amplitude was reduced. 6) The inverse relationship between the amplitude of tonic component and extracellular KCI concentration in the range of 40 to 150 mM KCI was more prominent in the antral circular muscle strip than in the fundic longitudinal muscle strip, where the amplitude of the tonic component decreased less steeply and was maintained higher at the same high K concentrations. 7) The tonic component was totally dependent on the external $Ca^{2+}$ and completely abolished by verapamil, while tile phasic component was far less dependent on the external $Ca^{2+}$ and partially suppressed by verapamil. From the above results, the following conclusions could be made. 1) The phasic component of K-contracture is produced both by intracellular $Ca^{2+}$ mobilization and by $Ca^{2+}$-influx from outside, while the tonic component is generated and maintained by the $Ca^{2+}-influx$ through the potential-dependent $Ca^{2+}$ channel. 2) The mechanism of reducing the free $Ca^{2+}$ concentration in the myoplasm seems to be more developed in the antral circular muscle than in the fundic longitudinal muscle. 3) The lower resting membrane potential of the fundic longitudinal muscle cell reflects a relatively high $P_{Na}/P_K$ ratio of about 0.108.