Cholesterol gallstones:Focusing on the role of interstitial Cajal-like cells

with a complex and multifactorial etiology.Declined gallbladder motility reportedly contributes to CG pathogenesis.Furthermore,interstitial Cajal-like cells(ICLCs)are reportedly present in human and guinea pig gallbladder tissue.ICLCs potentially contribute to the regulation of gallbladder motility,and aberrant conditions involving the loss of ICLCs and/or a reduction in its pacing potential and reactivity to cholecystokinin may promote CG pathogenesis.This review discusses the association between ICLCs and CG pathogenesis and provides a basis for further studies on the functions of ICLCs and the etiologies of CG.

Effect of cholesterol on in vitro cultured interstitial Cajal-like cells isolated from guinea pig gallbladders

BACKGROUND Loss and/or dysfunction of interstitial Cajal-like cells(ICLCs)in the gallbladder may promote cholesterol gallstone formation by decreasing gallbladder motility.AIM To study the effect of cholesterol on the proliferation and apoptosis of ICLCs from guinea pig gallbladders.METHODS Guinea pig gallbladder ICLCs were isolated and cultured in vitro.The cells were exposed to cholesterol solutions at different concentrations(0,25,50,and 100 mg/L)for 24 h.Then,cell proliferation was detected by the CCK-8 method and the apoptosis rate was detected by flow cytometry.Further,the expression of the c-Kit protein was detected by Western blot and the expression level of c-Kit m RNA in the cells was detected by real-time quantitative PCR.RESULTS After ICLCs were cultured with cholesterol at concentrations of 25,50,and 100 mg/L,the proliferation rates decreased significantly(P<0.05),whereas the apoptosis rates increased significantly(P<0.05).Moreover,the expression of cKit protein and m RNA decreased significantly(P<0.05).CONCLUSION High cholesterol concentrations can inhibit the proliferation of ICLCs and promote apoptosis.This decrease in the ICLC proliferation rate might be caused by the inhibition of the stem cell factor/c-Kit signaling pathway.

Expression and functional study of cholecystokinin-A receptors on the interstitial Cajal-like cells of the guinea pig common bile duct

BACKGROUND Many studies have shown that interstitial Cajal-like cell(ICLC)abnormalities are closely related to a variety of dynamic gastrointestinal disorders.ICLCs are pacemaker cells for gastrointestinal movement and are involved in the transmission of nerve impulses.AIM To elucidate the expression profile and significance of cholecystokinin-A(CCK-A)receptors in ICLCs in the common bile duct(CBD),as well as the role of CCK in regulating CBD motility through CCK-A receptors on CBD ICLCs.METHODS The levels of tyrosine kinase receptor(c-kit)and CCK-A receptors in CBD tissues and isolated CBD cells were quantified using the double immunofluorescence labeling technique.The CCK-mediated enhancement of the movement of CBD muscle strips through CBD ICLCs was observed by a muscle strip contraction test.RESULTS Immunofluorescence showed co-expression of c-kit and CCK-A receptors in the CBD muscularis layer.Observations of isolated CBD cells showed that c-kit was expressed on the surface of ICLCs,the cell body and synapse were colored and polygonal,and some cells presented protrusions and formed networks adjacent to the CBD while others formed filaments at the synaptic terminals of local cells.CCK-A receptors were also expressed on CBD ICLCs.At concentrations ranging from 10^(-6) mol/L to 10^(-10) mol/L,CCK promoted CBD smooth muscle contractility in a dose-dependent manner.In contrast,after ICLC removal,the contractility mediated by CCK in CBD smooth muscle decreased.CONCLUSION CCK-A receptors are highly expressed on CBD ICLCs,and CCK may regulate CBD motility through the CCK-A receptors on ICLCs.

Interstitial Cajal-like cells arrhythmogenic potential substrate of pulmonary veins

Interstitial Cajal-like cells(ICLC) have been found in the atrium,ventricle and pulmonary vein in human and anmials.ICLC with very long processes and space structure,Cell processes establish close spatial relationships between each other, as well as with cardiomyocyte and nerve endings.ICLC appear located among the myocardial cells and particularly at the border between the myocardial sleeve and pulmonary vein wall.ICLC seems to possess automaticity and triggered activity.ICLC is a potential substrate for arrhythmia.

Interstitial cells of Cajal, the Maestro in health and disease

Interstitial cells of Cajal (ICC) are important players in the symphony of gut motility. They have a very signif icant physiological role orchestrating the normal peristaltic activity of the digestive system. They are the pacemaker cells in gastrointestinal (GI) muscles. Absence, reduction in number or altered integrity of the ICC network may have a dramatic effect on GI system motility. More understanding of ICC physiology will foster advances in physiology of gut motility which will help in a future breakthrough in the pharmacological interventions to restore normal motor function of GI tract. This mini review describes what is known about the physiologic function and role of ICCs in GI system motility and in a variety of GI system motility disorders.

Jianpi Qingchang decoction regulates intestinal motility of dextran sulfate sodium-induced colitis through reducing autophagy of interstitial cells of Cajal

AIM To investigate the underlying effect of Jianpi Qingchang decoction(JQD) regulating intestinal motility of dextran sulfate sodium(DSS)-induced colitis in mice. METHODS C57BL/6 mice were randomly divided into four groups: the control group, the DSS group, the JQD group, and the 5-aminosalicylic acid group. Except for the control group, colitis was induced in other groups by giving distilled water containing 5% DSS. Seven days after modeling, the mice were administered corresponding drugs intragastrically. The mice were sacrificed on the 15^(th) day. The disease activity index, macroscopic and histopathologic lesions, and ultrastructure of colon interstitial cells of Cajal(ICC) were observed. The levels of tumor necrosis factor-alpha(TNF-α), interleukin(IL)-1β, IL-10 and interferon gamma(IFN-γ), the expression of nuclear factor-kappa B(NF-κB) p65, c-kit, microtubule-associated protein 1 light chain 3(LC3-Ⅱ) and Beclin-l m RNA, and the colonic smooth muscle tension were assessed. RESULTS Acute inflammation occurred in the mice administered DSS. Compared with the control group, the levels of IL-1β, TNF-α, IL-10 and IFN-γ, the expression of LC3-Ⅱ, Beclin-1 and NF-κB p65 m RNA, and the contractile frequency increased(P < 0.05), the expression of c-kit m RNA and the colonic smooth muscle contractile amplitude decreased in the DSS group(P < 0.05). Compared with the DSS group, the levels of IL-10 and IFN-γ, the expression of c-kit m RNA, and the colonic smooth muscle contractile amplitude increased(P < 0.05), the levels of TNF-α and IL-1β, the expression of LC3-Ⅱ, Beclin-1 and NF-κB p65 m RNA, and the contractile frequency decreased in the JQD group(P < 0.05).CONCLUSION JQD can regulate the intestinal motility of DSS-induced colitis in mice through suppressing intestinal inflammatory cascade reaction, reducing autophagy of ICC, and regulating the network path of ICC/smooth muscle cells.

Involvement of interstitial cells of Cajal in experimental severe acute pancreatitis in rats

AIM:To observe the changes in interstitial cells of Cajal(ICC) in rats with experimental severe acute pancreatitis(SAP).METHODS:A total of twenty-four SD rats were randomly divided into two groups(n = 12),namely the sham(S) group and the SAP group;the SAP rat model was established by retrograde injection of 5% sodium taurocholate(1.0 mL/kg) into the pancreatic duct.Twenty-four hours later intestinal motility was assessed by testing small intestinal propulsion rate,and then the rats were sacrificed.The pancreas and jejunum were resected and underwent routine pathologic examination.Immunohistochemical staining was used to detect c-kit-positive cells in the jejunum.Expression of c-kit mRNA was detected by real-time polymerase chain reaction,and the expression of c-kit protein was evaluated by Western blotting.Ultrastructure of ICC was evaluated by transmission electron microscopy.RESULTS:There was bleeding,necrosis and a largeamount of inflammatory cell infiltration in pancreatic tissue in the SAP group,while in jejunal tissue we observed a markedly denuded mucosal layer,loss of villous tissue and a slightly dilated muscular layer.The small intestinal propulsion rate was 68.66% ± 2.66% in the S group and 41.55% ± 3.85% in the SAP group.Compared with the S group,the rate of the SAP group decreased sharply.The density of c-kit-positive cells in the SAP group was significantly lower than in the S group;the respective mean densities were 88.47 ± 10.49 in the S group and 56.11 ± 7.09 in the SAP group.The levels of c-kit protein and mRNA were 0.36 ± 0.04 and 1.29 ± 0.91 in the SAP group,respectively,which were significantly lower than those in the S group(0.53 ± 0.06,0.64 ± 0.33,respectively).In the SAP group,ICC profiles showed the same change tendency,such as vacuolation of mitochondria,irregular vacuoles and loosened desmosome-like junctions.CONCLUSION:Decreased c-kit-positive cells and ultrastructural changes in ICC resulting from blockade of the c-kit signaling pathway are involved in the intestinal dysmotility associated with SAP.

Differential changes in intrinsic innervation and interstitial cells of Cajal in small bowel atresia in newborns

AIM: To investigate morphological changes of the enteric nervous system (ENS) and the interstitial cells of Cajal (ICCs) in small bowel atresia.METHODS: Resected small bowel specimens from affected patients (n = 7) were divided into three parts (proximal, atretic, distal). Standard histology and enzyme immunohistochemistry anti-S100, anti-protein gene product (PGP) 9.5, anti-neurofilament (NF), antic-kit-receptor (CD117) was carried out on conventional paraffin sections of the proximal and distal part. RESULTS: The neuronal and glial markers (PGP 9.5, NF, S-100) were expressed in hypertrophied ganglia and nerve fibres within the myenteric and submucosal plexuses. Furthermore, the submucous plexus contained typical giant ganglia. The innervation pattern of the proximal bowel resembled intestinal neuronal dysplasia. The density of myenteric ICCs was clearly reduced in the proximal bowel, whereas a moderate number of muscular ICCs were found. The anti-CD117 immunore- action revealed additional numerous mast cells. The distal bowel demonstrated normal morphology and density of the ENS, the ICCs and the mast cells.CONCLUSION: The proximal and distal bowel in small bowel atresia revealed clear changes in morphology and density of the ENS and ICCs.

Disruption of interstitial cells of Cajal networks after massive small bowel resection

AIM: To investigate the disruptions of interstitial cells of Cajal (ICC) in the remaining bowel in rats after massive small bowel resection (mSBR). METHODS: Thirty male Sprague-Dawley rats fitting entry criteria were divided randomly into three experimental groups (n = 10 each): Group A rats underwent bowel transection and re-anastomosis (sham) and tissue samples were harvested at day 7 post-surgery. Group B and C rats underwent 80% small bowel resection with tissue harvested from Group B rats at day 7 post-surgery, and from Group C rats at day 14 postsurgery. The distribution of ICC at the site of the resid-ual small bowel was evaluated by immunohistochemical analysis of small intestine samples. The ultrastructural changes of ICC in the remnant ileum of model rats 7 and 14 d after mSBR were analyzed by transmission electron microscopy. Intracellular recordings of slow wave oscillations were used to evaluate electrical pacemaking. The protein expression of c-kit, ICC phenotypic markers, and membrane-bound stem cell factor (mSCF) in intestinal smooth muscle of each group were detected by Western blotting. RESULTS: After mSBR, immunohistochemical analysis indicated that the number of c-kit-positive cells was dramatically decreased in Group B rats compared with sham tissues. Significant ultrastructural changes in ICC with associated smooth muscle hypertrophy were also observed. Disordered spontaneous rhythmic contractions with reduced amplitude (8.5 ± 1.4 mV vs 24.8 ± 1.3 mV, P = 0.037) and increased slow wave frequency (39.5 ± 2.1 cycles/min vs 33.0 ± 1.3 cycles/min, P = 0.044) were found in the residual intestinal smooth muscle 7 d post mSBR. The contractile function and electrical activity of intestinal circular smooth muscle returned to normal levels at 14 d post mSBR (amplitude, 14.9 ± 1.6 mV vs 24.8 ± 1.3 mV; frequency, 30.7 ± 1.7 cycles/min vs 33.0 ± 1.3 cycles/min). The expression of Mscf and c-kit protein was decreased at 7 d (P = 0.026), but gradually returned to normal levels at 14 d. The ICC and associated neural networks were disrupted, which was associated with the phenotype alterations of ICC. CONCLUSION: Massive small bowel resection in rats triggered damage to ICC networks and decreased the number of ICC leading to disordered intestinal rhythmicity. The mSCF/c-kit signaling pathway plays a role in the regulation and maintenance of ICC phenotypes.

Inhibition of pacemaker activity in interstitial cells of Cajal by LPS via NF-κB and MAP kinase

AIM:To investigate lipopolysaccharide(LPS) related signal transduction in interstitial cells of Cajal(ICCs) from mouse small intestine.METHODS:For this study,primary culture of ICCs was prepared from the small intestine of the mouse.LPS was treated to the cells prior to measurement of the membrane currents by using whole-cell patch clamp technique.Immunocytochemistry was used to examine the expression of the proteins in ICCs.RESULTS:LPS suppressed the pacemaker currents of ICCs and this could be blocked by AH6809,a prostaglandin E2-EP2 receptor antagonist or NG-Nitro-Larginine Methyl Ester,an inhibitor of nitric oxide(NO) synthase.Toll-like receptor 4,inducible NO synthase or cyclooxygenase-2 immunoreactivity by specific antibodies was detected on ICCs.Catalase(antioxidant agent) had no action on LPS-induced action in ICCs.LPS actions were blocked by nuclear factor kB(NF-kB) inhibitor,actinomycin D(a gene transcription inhibitor),PD 98059(a p42/44 mitogen-activated protein kinases inhibitor) or SB 203580 [a p38 mitogen-activated protein kinases(MAPK) inhibitor].SB 203580 also blocked the prostaglandin E2-induced action on pacemaker currents in ICCs but not NO.CONCLUSION:LPS inhibit the pacemaker currents in ICCs via prostaglandin E2-and NO-dependent mechanism through toll-like receptor 4 and suggest that MAPK and NF-kB are implicated in these actions.

Loss of interstitial cells of Cajal network in severe idiopathic gastroparesis

AIM: To report a case of severe idiopathic gastroparesis in complete absence of Kit-positive gastric interstitial cells of Cajal (ICC). METHODS: Gastric tissue from a patient with severe idiopathic gastroparesis unresponsive to medical treatment and requiring surgery was analyzed by conventional histology and immunohistochemistry. RESULTS: Gastric pacemaker cells expressing Kit receptor had completely disappeared while the local level of stem cell factor, the essential ligand for its development and maintenance, was increased. No signs of cell death were observed in the pacemaker region. CONCLUSION: These results are consistent with the hypothesis that a lack of Kit expression may lead to impaired functioning of ICC. Total gastrectomy proves to be curative.

Control of gallbladder contractions by cholecystokinin through cholecystokinin-A receptors on gallbladder interstitial cells of cajal

AIM: To identify the cholecystokinin (CCK)-A receptors (CCK-AR) on the guniea pig gallbladder interstitial cells of cajal (ICC) and to study CCK-8 induced gallbladder muscle strip contractions through the CCK-AR. METHODS: The existence of CCK-AR was examined by immunohistofluorescence on sectioned tissue and cultured cells. In vitro contractile response of guinea pig gallbladder muscle strips and the strips with ICC removed were also studied with CCK-8 receptors added. RESULTS: In tissue sections, intensely CCKAR- immunoreactive interstitial cells were found mainly in the muscular layers. In cultured cell sections, distinctive double staining of C-kit and CCK-AR ICCs were found. When we removed the ICC of the gallbladder, CCK-8 induced muscle strip contraction dose response curve significantly shifted to the right. CONCLUSION: We proved that both the existence of CCK-AR on the guinea pig gallbladder ICC and CCK evoked contraction are mediated through direct action on CCK-AR on the gallbladder ICC.

Characterization of smooth muscle, enteric nerve, interstitial cells of Cajal, and fibroblast-like cells in the gastric musculature of patients with diabetes mellitus

AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also conducted.RESULTS Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of DM.CONCLUSION Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.

Hwangryunhaedok-tang induces the depolarization of pacemaker potentials through 5-HT3 and 5-HT4 receptors in cultured murine small intestine interstitial cells of Cajal

AIM To investigate the effects of a water extract of Hwangryunhaedok-tang(HHTE) on the pacemaker potentials of mouse interstitial cells of Cajal(ICCs).METHODS We dissociated ICCs from small intestines and cultured. ICCs were immunologically identified using an antic-kit antibody. We used the whole-cell patch-clamp configuration to record the pacemaker potentials generated by cultured ICCs under the current clamp mode(I = 0). All experiments were performed at 30 ℃-32 ℃RESULTS HHTE dose-dependently depolarized ICC pacemaker potentials. Pretreatment with a 5-HT_3 receptor anta-gonist(Y25130) or a 5-HT_4 receptor antagonist(RS39604) blocked HHTE-induced pacemaker potential depolarizations, whereas pretreatment with a 5-HT7 receptor antagonist(SB269970) did not. Intracellular GDPβS inhibited HHTE-induced pacemaker potential depolarization and pretreatment with a Ca^(2+)-free solution or thapsigargin abolished the pacemaker potentials. In the presence of a Ca^(2+)-free solution or thapsigargin, HHTE did not depolarize ICC pacemaker potentials. In addition, HHTE-induced pacemaker potential depolarization was unaffected by a PKC inhibitor(calphostin C) or a Rho kinase inhibitor(Y27632). Of the four ingredients of HHT, Coptidis Rhizoma and Gardeniae Fructus more effectively inhibited pacemaker potential depolarization.CONCLUSION These results suggest that HHTE dose-dependently depolarizes ICC pacemaker potentials through 5-HT_3 and 5-HT_4 receptors via external and internal Ca^(2+) regulation and via G protein-, PKC-and Rho kinase-independent pathways.

Long-pulse gastric electrical stimulation protects interstitial cells of Cajal in diabetic rats via IGF-1 signaling pathway

AIM: To investigate the effects of different parameters of gastric electrical stimulation (GES) on interstitial cells of Cajal (ICCs) and changes in the insulin-like growth factor 1 (IGF-1) signal pathway in streptozotocin-induced diabetic rats. METHODS: Male rats were randomized into control, diabetic (DM), diabetic with sham GES (DM + SGES), diabetic with GES1 (5.5 cpm, 100 ms, 4 mA) (DM + GES1), diabetic with GES2 (5.5 cpm, 300 ms, 4 mA) (DM + GES2) and diabetic with GES3 (5.5 cpm, 550 ms, 2 mA) (DM + GES3) groups. The expression levels of c-kit, M-SCF and IGF-1 receptors were evaluated in the gastric antrum using Western blot analysis. The distribution of ICCs was observed using immunolabeling for c-kit, while smooth muscle cells and IGF-1 receptors were identified using alpha-SMA and IGF-1R antibodies. Serum level of IGF-1 was tested using enzyme-linked immunosorbent assay. RESULTS: Gastric emptying was delayed in the DM group but improved in all GES groups, especially in the GES2 group. The expression levels of c-kit, M-SCF and IGF-1R were decreased in the DM group but increased in all GES groups. More ICCs (c-kit(+)) and smooth muscle cells (alpha-SMA(+)/IGF-1R(+)) were observed in all GES groups than in the DM group. The average level of IGF-1 in the DM group was markedly decreased, but it was up-regulated in all GES groups, especially in the GES2 group. CONCLUSION: The results suggest that long-pulse GES promotes the regeneration of ICCs. The IGF-1 signaling pathway might be involved in the mechanism underlying this process, which results in improved gastric emptying.

Dissociation, culture and morphologic changes of interstitial cells of Cajal in vitro

AIM: To study the method of dissociation, culture and investigate its morphologic changes in vitro of interstitial cells of Cajal (ICC).METHODS: Enzymatic digestion and Ficoll density centrifugation were used to dissociate ICC from the ileal segment of mice. Factors including contamination, Ca2+, Mg2+ and collagenase, and stem cell factor, etc., were investigated.ACK2, the antibody of c-kit, was used to identify the cultured ICC. Both light microscope and fluorescence microscope were used to observe the changes of ICC in vitro.RESULTS: The method for dissociation and culture of ICC in vitro was successfully established. After 24 h, cultured ICC exhibited a few axis-cylinders, and longer axis-cylinders were observed to form synapse of each other after 3 d. More widespread connections formed within 7 d in vitro. The changes of its morphologic character were obvious within 7 d; however, there were no obvious morphologic changes after 30 d.CONCLUSION: Many factors can influence the dissociation and culture of ICC.

Morphological changes in interstitial cells of Cajal in the deep muscular plexus and enteric motor neurons of the intestine in rats with multiple organ dysfunction syndrome

BACKGROUND：Gastrointestinal motility dysfunction in multiple organ dysfunction syndrome （MODS） has been reported to be related to damage to interstitial cells of Cajal （ICC）. In the entedc nervous system, ICC and smooth muscle cells are connected in a network to form a special functional unit. Many gastrointestinal motility dysfunction diseases are associated with damage to this network.OBJECTIVE：To investigate the morphological changes of intestinal ICC, and to explore the mechanisms underlying gastrointestinal motility dysfunction in rats with MODS.DESIGN, TIME AND SE＇I-FING：The randomized, controlled, experiment was performed at the Central Laboratory of the First Affiliated Hospital of Dalian Medical University of China between June 2007 and March 2009.MATERIALS：Escherichia coli （E. colistrain O127 H6） and bovine serum albumin were purchased from Sigma, USA.METHODS：A total of 40 Wistar rats were equally and randomly divided into MODS group and control group. Suspension of E. coil strain O127 H6 containing BaSO4 and saline were sterilely injected into the abdominal cavity of rats in the MODS and control groups, respectively.MAIN OUTCOME MEASURES：Immunohistochemical double-staining and confocal laser scanning microscopy were used to observe the morphological changes in intestinal cholinergic nerves and ICC in the deep muscular plexus network. Electron microscopy was employed to evaluate the ultrastructural features of ICC in the deep muscular plexus of rats with MODS.RESULTS：Compared with the control group, the distributions and densities of cholinergic/nitrergic newes and ICC in the deep muscular plexus were significantly decreased in the MODS group （P 〈 0.01）. The enteric nerve-ICC network were disrupted.CONCLUSION：There is ultrastructural injury in the ICC in the deep muscular plexus and enteric nerves of the intestine in rats with MODS, which may be associated with the dysmotility of the gastrointestinal tract in MODS.

Different distributions of interstitial cells of Cajal and platelet-derived growth factor receptor-α positive cells in colonic smooth muscle cell/interstitial cell of Cajal/plateletderived growth factor receptor-α positive cell syncytium in mice

AIM To investigate the distribution and function of interstitialcells of Cajal(ICCs) and platelet-derived growth factor receptor-α positive(PDGFRα+) cells in the proximal and distal colon.METHODS The comparison of colonic transit in the proximal and distal ends was performed by colonic migrating motor complexes(CMMCs). The tension of the colonic smooth muscle was examined by smooth muscle spontaneous contractile experiments with both ends of the smooth muscle strip tied with a silk thread. Intracellular recordings were used to assess electrical field stimulation(EFS)-induced inhibitory junction potentials(IJP) on the colonic smooth muscle. Western blot analysis was used to examine the expression levels of ICCs and PDGFRα in the colonic smooth muscle.RESULTS Treatment with NG-nitro-L-arginine methyl ester hydrochloride(L-NAME) significantly increased the CMMC frequency and spontaneous contractions, especially in the proximal colon, while treatment with MRS2500 increased only distal CMMC activity and smooth muscle contractions. Both CMMCs and spontaneous contractions were markedly inhibited by NPPB, especially in the proximal colon. Accordingly, CyPPA sharply inhibited the distal contraction of both CMMCs and spontaneous contractions. Additionally, the amplitude of stimulationinduced nitric oxide(NO)/ICC-dependent slow IJPs(sIJPs) by intracellular recordings from the smooth muscles in the proximal colon was larger than that in the distal colon, while the amplitude of electric field stimulationinduced purinergic/PDGFRα-dependent fast IJPs(fIJPs) in the distal colon was larger than that in the proximal colon. Consistently, protein expression levels of c-Kit and anoctamin-1(ANO1) in the proximal colon were much higher, while protein expression levels of PDGFRα and small conductance calcium-activated potassium channel 3(SK3) in the distal colon were much higher.CONCLUSION The ICCs are mainly distributed in the proximal colon and there are more PDGFRα+ cells are in the distal colon, which generates a pressure gradient between the two ends of the colon to propel the feces to the anus.

Effects of Lizhong Tang on cultured mouse small intestine interstitial cells of Cajal

AIM:To investigate the effects of Lizhong Tang,an herbal product used in traditional Chinese medicine,on mouse small intestine interstitial cells of Cajal(ICCs).METHODS:Enzymatic digestions were used to dissociate ICCs from mouse small intestine tissues.The ICCs were morphologically distinct from other cell types in culture and were identified using phase contrast microscopy after verification with anti c-kit antibody.A whole-cell patch-clamp configuration was used to record potentials(current clamp) from cultured ICCs.All of the experiments were performed at 30-32 ℃.RESULTS:ICCs generated pacemaker potentials,and Lizhong Tang produced membrane depolarization in current-clamp mode.The application of flufenamic acid(a nonselective cation channel blocker) abolished the generation of pacemaker potentials by Lizhong Tang.Pretreatment with thapsigargin(a Ca 2+-ATPase inhibi-tor in the endoplasmic reticulum) also abolished the generation of pacemaker potentials by Lizhong Tang.However,pacemaker potentials were completely abolished in the presence of an external Ca 2+-free solution,and under this condition,Lizhong Tang induced membrane depolarizations.Furthermore,When GDPβ-S(1 mmol/L) was in the pipette solution,Lizhong Tang still induced membrane depolarizations.In addition,membrane depolarizations were not inhibited by chelerythrine or calphostin C,which are protein kinase C inhibitors,but were inhibited by U-73122,an active phospholipase C inhibitors.CONCLUSION:These results suggest that Lizhong Tang might affect gastrointestinal motility by modulating pacemaker activity in interstitial cells of Cajal.

Identification of TRPM7 channels in human intestinal interstitial cells of Cajal

AIM： To investigate the characteristics of slow electrical waves and the presence of transient receptor potential melastatin-type 7 （TRPM7） in the human gastrointestinal （GI） tract. METHODS： Conventional microelectrode techniques were used to record intracellular electrical responses from human GI smooth muscle tissue. Immunohistochemistry was used to identify TRPM7 channels in interstitial cells of Cajat （ICCs）. RESULTS： The human GI tract generated slow electrical waves and had ICCs which functioned as pacemak er cells. Flufenamic acid, a nonselective cation channel blocker, and 2-APB （2-aminoethoxydiphenyl borate） and La3＋, TRPM7 channel blockers, inhibited the slowwaves. Also, TRPM7 channels were expressed in ICCs in human tissue. CONCLUSION： These results suggest that the human GI tract generates slow waves and that TRPM7 channels expressed in the ICCs may be involved in the gen- eration of the slow waves.