• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.7-11
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• 2006

Interstitial cells of Cajal (ICCs) are pacemakers in gastrointestinal tracts, regulating rhythmicity by activating nonselective cation channels (NSCCs). In the present study, we investigated the general characteristics and pH-mediated regulation of pacemaker activity in cultured interstitial cells of Cajal. Under voltage clamp mode and at the holding potential of -60 mV, the I-V relationships and difference current showed that there was no reversal potential and voltage-independent inward current. Also, when the holding potentials were changed from +20 mV to -80 mV with intervals of 20 mV, there was little difference in inward current. In pacemaker activity, the resting membrane potential (RMP) was depolarized (In pH 5.5, $23{\pm}1.5$ mV depolarized) and the amplitude was decreased by a decrease of the extracellular pH. However, in case of increase of extracellular pH, the RMP was slightly hyperpolarized and the amplitude was decreased a little. The melastatin type transient receptor potential (TRPM) channel 7 has been suggested to be required for intestinal pacemaking activity. TRPM7 produced large outward currents and small inward currents by voltage ramps, ranging from +100 to -100 mV from a holding potential of -60 mV. The inward current of TRPM7 was dramatically increased by a decrease in the extracellular pH. At pH 4.0, the average inward current amplitude measured at -100 mV was increased by about 7 fold, compared with the current amplitude at pH 7.4. Changes in the outward current (measured at +100 mV) were much smaller than those of the inward current. These results indicate that the resting membrane potential of pacemaking activity might be depolarized by external acidic pH through TRPM7 that is required for intestinal pacemaking activity.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.1
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• pp.25-30
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• 2008

Although many studies show that thromboxane $A_2\;(TXA_2)$ has the action of gastrointestinal (GI) motility using GI muscle cells and tissue, there are no reports on the effects of $TXA_2$ on interstitial cells of Cajal (ICC) that function as pacemaker cells in GI tract. So, we studied the modulation of pacemaker activities by $TXA_2$ in ICC with whole cell patch-clamp technique. Externally applied $TXA_2\;(5{\mu}M)$ produced membrane depolarization in current-clamp mode and increased tonic inward pacemaker currents in voltage-clamp mode. The tonic inward currents by $TXA_2$ were inhibited by intracellular application of GDP-${\beta}$-S. The pretreatment of ICC with $Ca^{2+}$ free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the $TXA_2$-induced tonic inward currents. However, chelerythrine or calphostin C, protein kinase C inhibitors, did not block the $TXA_2$-induced effects on pacemaker currents. These results suggest that $TXA_2$ can regulate intestinal motility through the modulation of ICC pacemaker activities. This modulation of pacemaker activities by $TXA_2$ may occur by the activation of G protein and PKC independent pathway via extra and intracellular $Ca^{2+}$ modulation.

• Animal Bioscience
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• v.36 no.5
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• pp.740-752
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• 2023

Objective: Dietary phytase increases bioavailability of phytate-bound phosphorus (P) in pig nutrition affecting dietary calcium (Ca) to P ratio, intestinal uptake, and systemic utilization of both minerals, which may contribute to improper bone mineralization. We used phytase to assess long-term effects of two dietary available P (aP) levels using a one-phase feeding system on gene expression related to Ca and P homeostasis along the intestinal tract and in the kidney, short-chain fatty acids in stomach, cecum, and colon, serum, and bone parameters in growing gilts and barrows. Methods: Growing pigs (37.9±6.2 kg) had either free access to a diet without (Con; 75 gilts and 69 barrows) or with phytase (650 phytase units; n = 72/diet) for 56 days. Samples of blood, duodenal, jejunal, ileal, cecal, and colonic mucosa and digesta, kidney, and metacarpal bones were collected from 24 pigs (6 gilts and 6 barrows per diet). Results: Phytase decreased daily feed intake and average daily gain, whereas aP intake increased with phytase versus Con diet (p<0.05). Gilts had higher colonic expression of TRPV5, CDH1, CLDN4, ZO1, and OCLN and renal expression of TRPV5 and SLC34A3 compared to barrows (p<0.05). Phytase increased duodenal expression of TRPV5, TRPV6, CALB1, PMCA1b, CDH1, CLDN4, ZO1, and OCLN compared to Con diet (p<0.05). Furthermore, phytase increased expression of SCL34A2 in cecum and of FGF23 and CLDN4 in colon compared to Con diet (p<0.05). Alongside, phytase decreased gastric propionate, cecal valerate, and colonic caproate versus Con diet (p<0.05). Phytase reduced cortical wall thickness and index of metacarpal bones (p<0.05). Conclusion: Gene expression results suggested an intestinal adaptation to increased dietary aP amount by increasing duodenal trans- and paracellular Ca absorption to balance the systemically available Ca and P levels, whereas no adaption of relevant gene expression in kidney occurred. Greater average daily gain in barrows related to higher feed intake.

• Animal Bioscience
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• v.34 no.2
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• pp.243-255
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• 2021

Objective: Deoxynivalenol (DON) and zearalenone (ZEN) are mycotoxins that frequently contaminate maize and grain cereals, imposing risks to the health of both humans and animals and leading to economic losses. The gut microbiome has been shown to help combat the effects of such toxins, with certain microorganisms reported to contribute significantly to the detoxification process. Methods: We examined the cecum contents of three different dietary groups of pigs (control, as well as diets contaminated with 8 mg DON/kg feed or 0.8 mg ZEN/kg feed). Bacterial 16S rRNA gene amplicons were acquired from the cecum contents and evaluated by next-generation sequencing. Results: A total of 2,539,288 sequences were generated with ~500 nucleotide read lengths. Firmicutes, Bacteroidetes, and Proteobacteria were the dominant phyla, occupying more than 96% of all three groups. Lactobacillus, Bacteroides, Megasphaera, and Campylobacter showed potential as biomarkers for each group. Particularly, Lactobacillus and Bacteroides were more abundant in the DON and ZEN groups than in the control. Additionally, 52,414 operational taxonomic units were detected in the three groups; those of Bacteroides, Lactobacillus, Campylobacter, and Prevotella were most dominant and significantly varied between groups. Hence, contamination of feed by DON and ZEN affected the cecum microbiota, while Lactobacillus and Bacteroides were highly abundant and positively influenced the host physiology. Conclusion: Lactobacillus and Bacteroides play key roles in the process of detoxification and improving the immune response. We, therefore, believe that these results may be useful for determining whether disturbances in the intestinal microflora, such as the toxic effects of DON and ZEN, can be treated by modulating the intestinal bacterial flora.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.5
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• pp.814-821
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• 2010

The purpose of this study was to investigate effects of moxibustion at combined acupoints on sex and age in rats. This study measured the effects of moxibustion on small intestinal motility in rats. Cauterizing with moxa was applied 5 times to the acupoints on SI8, LI11 SP9 and ST36 under enflurane anesthesia in the groups divided with sex and age. In single acupoint groups, cauterizing with moxa on ST36 increased in all of sex and age groups. The SP9 group with 5, 6 weeks in female and 5, 8 weeks in male, the SI8 group with 5, 7 weeks in female and only 7 weeks in male, the LI11 group with only 5, 6, 7 weeks in female and only 7 weeks in male showed increasing on small intestinal motility. In combined acupoints groups, the SI8+SP9 group with 7 weeks in female and 5, 6, 8 weeks in male, the SI8+ST36 group with 5, 6 weeks in female and 8 weeks in male, the LI11+SP9 group with 5, 6 weeks in female and 6 weeks in male, the LI11+ST36 group with 5 weeks in female and 5, 6, 7 weeks in male showed increasing respectively. Although these different according to the sex and age in rats do not have a established tendency, the results suggested that the effects of combined acupoints of cauterizing with moxa have relation with individuality.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.4
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• pp.375-383
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• 2021

The intestinal barrier function disrupted in sepsis, while little is known about the variation in different phases of sepsis. In this study, mouse models of sepsis were established by caecal ligation and puncture (CLP). The H&E staining of sections and serum diamine oxidase concentration were evaluated at different timepoint after CLP. TUNEL assay and EdU staining were performed to evaluate the apoptosis and proliferation of intestinal epithelium. Relative protein expression was assessed by Western blotting and serum concentrations of pro-inflammatory cytokines was measured by ELISA. The disruption of intestinal barrier worsened in the first 24 h after the onset of sepsis and gradually recovered over the next 24 h. The percentage of apoptotic cell increased in the first 24 h and dropped at 48 h, accompanied with the proliferative rate of intestinal epithelium inhibited in the first 6 h and regained in the later period. Furthermore, the activity of nuclear factor kappa B (NF-κB) presented similar trend with the intestinal barrier function, shared positive correction with apoptosis of intestinal epithelium. These findings reveal the conversion process of intestinal barrier function in sepsis and this process is closely correlated with the activity of NF-κB signaling.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.2
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• pp.71-75
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• 2010

To investigate the intestinal absorption of a fibrinolytic and proteolytic lumbrokinase extracted from Eisenia andrei, we used rat everted gut sacs and an in situ closed-loop recirculation method. We extracted lumbrokinase from Eisenia andrei, and then raised polyclonal antibody against lumbrokinase. Fibrinolytic activity and proteolytic activity in the serosal side of rat everted gut sacs incubated with lumbrokinase showed dose- and time-dependent patterns. Immunological results obtained by western blotting serosal side solution using rat everted gut sacs method showed that lumbrokinase proteins between 33.6 and 54.7 kDa are absorbed mostly by the intestinal epithelium. Furthermore, MALDI- TOF mass spectrometric analysis of plasma fractions obtained by in situ recirculation method confirmed that lumbrokinase F1 is absorbed into blood. These results support the notion that lumbrokinase can be absorbed from mucosal lumen into blood by oral administration.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.51.1-51.1
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• 2011

An electrospun Poly (lactice-co-glycolide acid) (PLGA) and Gelatin nanofiber tube was fabricated for potential intestinal stent application. Mechanical properties of tube were evaluated by tensile strength and burst strength tests. Physical and chemical properties were evaluated by contact angle measurement, swelling rates and porosity measurements. Biodegradability was investigated by immersion in simulated body fluid (SBF). Biocompatibility was investigated in vitro by cytotoxicity and proliferation studies by MTT assay, confocal microscopy and western blot using IEC-18 (Rat intestinal epithelial cell). After intestinal stent was implanted into rat bowel for periods from 7 to 10days, it was then analyzed using micro-computed tomography (Micro CT) and X-ray techniques. Futhermore, histological analysis was performed by hematoxylin-eosin (H&E) stain.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.21-26
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• 2001

To examine functionality of depolymerized alginate obtained by hydrolysis of alginate through a heating process at $121^{\circ}C$ on gastrointestinal physiology, the changes of body weight, organ weight and length, pancreatic and small intestinal composition, and light microscopy (LM) observation of small intestinal microvilli's appearances were checked in the rats. Rats were fed diets containing $1\%, 5\%, and 10\%$ of each depolymerized alginate (HAG-10, HAG-50, HAG-100) and alginate for 35 days, The feeding of 5 and $10\%$ HAG-50 and $10\%$ alginate diets for 35 days significantly depressed the body weight gain, but increased the length and weight of the small intestine and cecum in rats (p<0.01). Pancreatic protease activity was decreased significantly (p<0.01) in all groups except lo/o of HAG-10 diets, but the protein content increased in all groups, However, pancreatic amylase and lipase activities as well as DNA and RNA content were not significantly different. The small intestinal protein and the DNA content were the highest in diets fed $5\%$ HAG-50; RNA content increased significantly (p<0.01) in all groups except in the fiber-free diets. Light microscopy (LM) observation showed growth of small intestinal microvilli with numerous ridges; the multiplication of the convolution goblet cells in rats fed with diets containing $5\%$ of HAG-50 were more than others group.

• The Korean Journal of Physiology
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• v.7 no.1
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• pp.23-31
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• 1973

Numerous factors concern with the absorption of substances through the membrane of the gastrointestinal tract. To simplify the experimental condition, present work has been restricted to observe the disappearance rate of substance from the intestinal loop which was made in the jejunum, 70 cm apart from the pylorus of the adult rabbit. The purpose of the study is to clarify the absorption of urea through the jejunal wall is solely attributable to the concentration difference between the luminal fluid and plasma, and to observe the effect of adding red pepper upon the rate of absorption. The rabbits were anesthetized with nembutal, 35mg/kg I.V. Jejunal loop was made by ligating at 2 spots, 70 cm and 80cm apart from the pylorus. After rinsing with normal saline solution through the polyethylene tubing inserted from the end of the loop, 8 ml of test solution was placed through the same tubing. The test solution contained 200 mg% of urea and 150mg% of polyethylene glycol(M.W. 4,000) in normal saline solution. Right after placing the test solution the first specimen was taken through the tubing, and successive samplings were performed at 5, 10, 20, and 30 minutes. Logarithm of the difference of urea concentration between the luminal fluid and plasma was plotted against time elapsed after the onset of the experiment. If straight line is revealed, it would verify the nature of transport mechanism as diffusion, obeying the Fick's principle. The concentration of polyethylene glycol (PEG) was also measured in order to examine the change in the volume. PEG was used as the marker substance because it is not absorbable in the intestinal tract. Consequently the concentration of PEG relates inversely to the volume of the loop. Instantaneous concentration of urea in the loop times the volume will give the amount of urea remaining in the luminal fluid. The change in the amount of any substance is directly relate to the volume of the compartment and differs from the change in the concentration which is independent of the volume. After completion of the experiment without red pepper, it was added in the test solution and was centrifuged after thorough mixing. Supernatant of the mixture was placed in the loop and similar sampling were performed with the same time intervals that of previous run in order to observe the effects of the red pepper on the passive transport of the water soluble small substance, urea. The results obtained were as follows: 1. Logarithm of the concentration difference of urea between the luminal fluid and plasma was diminished exponentially as time elapsed. The decay constant in the experiment without red pepper was 0.0563/min. By adding red pepper in the test solution as much as the concentration rose to 4,000 mg% and 8,000 mg%, the decay constants were lowered to 0.0493/min and to 0.0506/min, respectively. The time interval by which the concentration difference dropped to one half of the initial value was prolonged. Without red pepper the half concentration time was 13.30 minutes, and by adding extract of red pepper, 15.31 minutes and 15.71 minutes were revealed. 2. The profile of the diminishing rate of tile amount of urea was quite different from that of the concentration because of the change in the volume of the loop during the observed period. 3. By adding the extract of red pepper, it slowed down the rate of absorption of urea in the intestinal loop, suggesting an increase in the diffusional barrier. 4. Larger dosage of red pepper brought an increase in the secretion of intestinal fluid with concomitant expansion of the luminal volume, and the retardation of the absorption of urea was noticed. This effect was largely dependent on the sensitivity of the individual animal to the red pepper, extract. The amount of urea remained after 10 minutes interval was 55.5% of the initial amount in the experiment without red pepper. On the other hand it was not consistent after administration of red pepper, showing 50.6% and 66.5% of the initial figures by adding 400 mg and 800 mg of red pepper in the test solution, respectively. It was postulated that symptom of diarrhea often encountered by taking a hot (red pepper) food might be attributable to the increase of secretion and the retardation of absorption in the intestinal tract.