BACKGROUND AND OBJECTIVES: This study was aimed to explore the effects of the 5-hydroxytryptamine (5-HT) on potassium currents in rat vestibular nuclear neurons. MATERIALS AND METHOD: Sprague-Dawley rats aged 14 to 16 days were anesthetized with ether and decapitated. After enzymatic digestion, the portion of medial vestibular nucleus neuron was removed by micropunching and gently agitated. The dissociated neurons were transferred into a recording chamber mounted on an inverted microscope and whole-cell membrane currents were recorded at room temperature by using standard patch-clamp techniques. RESULTS: When cells were held at -70 mV and depolarized from -60 mV to +40 mV in 10 mV increments, sustained outward potassium currents were evoked. The response of medial vestibular nuclear neurons to 5-HT was not uniform. The outward potassium currents were increased in 17 of 40 cells and decreased in 23 of 40 cells. 5-carboxamidotryptamine, 5-HT1 agonist increased the outward potassium currents of the medial vestibular nuclear cell. alpha-methyl-5-hydroxytryptamine, 5-HT2 agonist decreased the outward potassium currents of the medial vestibular nuclear cell. CONCLUSION: These results suggest that 5-HT affects the potassium currents of the cell with different effects according to the receptor subtype on which it acts.
Animals ; Digestion ; Dihydroergotamine ; Ether ; Membranes ; Neurons* ; Patch-Clamp Techniques ; Potassium Channels ; Potassium* ; Rats* ; Rats, Sprague-Dawley ; Serotonin 5-HT1 Receptor Agonists ; Serotonin 5-HT2 Receptor Agonists ; Serotonin* ; Vestibular Nuclei

The effects of nitric oxide on the vestibular function recovery following unilateral labyrinthectomy (UL) were studied. Sprague-Dawley male rats, treated with nitric oxide liberating agent sodium nitroprusside (SNP) and NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME), were subjected to destruction of the unilateral vestibular apparatus, and then spontaneous nystagmus was observed in the rat. To explore the effects of nitric oxide on the neuronal excitability, whole cell patch clamp technique was applied on isolated medial vestibular nuclear neurons. The frequency of spontaneous nystagmus in SNP treated rats was lesser than that of spontaneous nystagmus in control animals. In contrast, pre-UL treatment with L-NAME resulted in a significant increase in spontaneous nystagmus frequency. In addition, SNP increased the frequency of spontaneous action potential in isolated medial vestibular nuclear neurons. Potassium currents of the vestibular nuclear neurons were inhibited by SNP. After blockade of calcium dependent potassium currents by high EGTA (11 mM) in a pipette solution, SNP did not inhibit outward potassium currents. 1H-[1, 2, 4] oxadiazolo [4, 3-a] quinozalin-1-one (ODQ), a specific inhibitor of soluble guanylyl cyclase, inhibited the effects of SNP on the spontaneous firing and the potassium current. These results suggest that nitric oxide after unilateral labyrin- thectomy would help to facilitate vestibular compensation by inhibiting calcium-dependent potassium currents through increasing intracellular cGMP, and consequently would increase excitability in ipsilateral vestibular nuclear neurons.
Action Potentials ; Animals ; Calcium ; Compensation and Redress* ; Egtazic Acid ; Fires ; Guanylate Cyclase ; Humans ; Male ; Neurons ; NG-Nitroarginine Methyl Ester ; Nitric Oxide* ; Nitroprusside ; Potassium ; Rats ; Rats, Sprague-Dawley ; Recovery of Function ; Vestibule, Labyrinth

Interstitial cells of Cajal (ICCs) from the urinary bladder regulate detrusor smooth muscle activities. We cultured ICCs from the urinary bladder of mice and performed patch clamp and intracellular Ca2+ ([Ca2+]i) imaging to investigate whether cultured ICCs can be a valuable tool for cellular functional studies. The cultured ICCs displayed two types of spontaneous electrical activities which are similar to those recorded in intact bladder tissues. Spontaneous electrical activities of cultured ICCs were nifedipine-sensitive. Carbachol and ATP, both excitatory neurotransmitters in the urinary bladder, depolarized the membrane and increased the frequency of spike potentials. Carbachol increased [Ca2+]i oscillations and basal Ca2+ levels, which were blocked by atropine. These results suggest that cultured ICCs from the urinary bladder retain rhythmic phenotypes similar to the spontaneous electrical activities recorded from the intact urinary bladder. Therefore, we suggest that cultured ICCs from the urinary bladder may be useful for cellular and molecular studies of ICCs.
Action Potentials ; Adenosine Triphosphate ; Animals ; Atropine ; Carbachol ; Interstitial Cells of Cajal* ; Membranes ; Mice* ; Muscle, Smooth ; Neurotransmitter Agents ; Phenotype ; Urinary Bladder*

Adenomyoma of the gastrointestinal tract has been considered to be a form of pancreatic heterotopia. Heterotopic pancreatic tissue in the gastrointestinal tract is a relatively not uncommon abnormality, but adenomyoma is a rarely reported tumor and its ineidence is difficult to determine. Adenomyoma is similar to aberrant pancreas in both appearance and location, and cannot be differentiated endoscopically or radiographically. Histologically, adenomyoma is primarily composed of smooth muscle and undifferentiated duct like structures. It is usually of no clinical importance and incidentally detected, but according to its location and size of the mass, it may become a serious clinical problem. Its real importance lies in the recognition of its existence, to facilitate a timely diagnosis, We present a case of adenomyoma of the duodenum with a brief literature review.
Adenomyoma* ; Diagnosis ; Duodenum* ; Esophagus* ; Gastrointestinal Tract ; Intestines* ; Muscle, Smooth ; Pancreas ; Stomach*

BACKGROUND: It has been known that the sero- logic markers of infectivity and viral replication in patients with hepatitis B virus(HBV) infection are hepatitis B e antigen(HBeAg), HRV DNA and HBV DNA polymerase. METHODS: In order to clarify the relationship between chronic liver diseases and HBV infection, and the mechanism of chronicity in HBV related liver diseases, the expression patterns of hepatic HBeAg by imrnunohistochemical stain and histologic activity index(HAI) were studied from 10% formalin fixed paraffin embedded tissues in 114 patients performed liver biopsy. RESULTS: The results were as follows: 1) Incidence of serum HReAg positivity in HBsAg positive patients was 74.6% and that of hepatic HBeAg expression was 77.6% among serum HBeAg positive cases. Hepatic HBeAg expression was 72.4% in serum HBeAg negative cases. 2) In serum HBeAg positive cases, almost all infected hepatocytes exhibited cytoplasmic HBeAg expression and half of patients showed nuclear HBeAg expression, but cytoplasmic HBeAg expression was solely predominant in serum HBeAg negative cases. Hepatic HBeAg expression showed a decreasing trend from AVH and CPH, through CAH, to cirrhosis with or without HCC, which was a consistent finding with serum HBeAg in decreasing manner. Hepatic HBeAg expreassion was highly sustained in about 60-90% of cases, regardless of duration of their illnesses. 3) HAI showed slighf3y higher tendency in patients with hepatic HBeAg negative expression than in positive cases. CONCLUSION: The above results suggest that HBeAg may play a role as a viral target antigen for immune-mediated liver injury and may be also related to the pathogenetic mechanism of chronicity in chronic hepatitis B.
Biopsy ; Cytoplasm ; DNA ; Fibrosis ; Formaldehyde ; Hepatitis B e Antigens ; Hepatitis B Surface Antigens ; Hepatitis B virus* ; Hepatitis B* ; Hepatitis B, Chronic ; Hepatitis* ; Hepatocytes ; Humans ; Incidence ; Liver ; Liver Diseases ; Logic ; Paraffin

BACKGROUND/AIMS: Tamoxifen is a widely used anticancer drug for breast cancer with frequent gastrointestinal side effects. Changes in gastrointestinal motility is associated with altered activities of membrane ion channels. Ion channels have important role in regulating membrane potential and cell excitability. This study was performed to investigate the effects of tamoxifen on the membrane ionic currents in colonic smooth muscle cells. METHODS: Murine colonic smooth muscle cells were isolated from the proximal colon using collagenase, and the membrane currents were recorded using a whole-cell patch clamp technique. RESULTS: Two types of voltage-dependent K+ currents were recorded (A-type and delayed rectifier K+ currents). Tamoxifen inhibited both types of voltage-dependent K+ currents in a dose-dependent manner. However, tamoxifen did not change the half-inactivation potential and the recovery time of voltage-dependent K+ currents. Chelerythrine, a protein kinase C inhibitor or phorbol 12, 13-dibutyrate, a protein kinase C activator did not affect the voltage-dependent K+ currents. Guanosine 5'-O-(2-thio-diphosphate) did not affect the tamoxifen-induced inhibition of voltage-dependent K+ currents. Tamoxifen inhibited voltage-dependent Ca2+ currents completely in whole-test ranges. CONCLUSIONS: These results suggest that tamoxifen can alter various membrane ionic currents in smooth muscle cells and cause some adverse effects on the gastrointestinal motility.
Animals ; Antineoplastic Agents, Hormonal/*pharmacology ; Calcium Channels/drug effects ; Colon/*drug effects/physiology ; English Abstract ; In Vitro ; Membrane Potentials ; Mice ; Myocytes, Smooth Muscle/*drug effects/physiology ; Potassium Channels/*drug effects ; Tamoxifen/*pharmacology

OBJECTIVES: In mammals, cochlear hair cell loss is irreversible and may result in a permanent sensorineural hearing loss. Secondary to this hair cell loss, a progressive loss of spiral ganglion neurons (SGNs) is presented. In this study, we have investigated the effects of neural-induced human mesenchymal stem cells (NI-hMSCs) from human bone marrow on sensory neuronal regeneration from neomycin treated deafened guinea pig cochleae. METHODS: HMSCs were isolated from the bone marrow which was obtained from the mastoid process during mastoidectomy for ear surgery. Following neural induction with basic fibroblast growth factor and forskolin, we studied the several neural marker and performed electrophysiological analysis. NI-hMSCs were transplanted into the neomycin treated deafened guinea pig cochlea. Engraftment of NI-hMSCs was evaluated immunohistologically at 8 weeks after transplantation. RESULTS: Following neural differentiation, hMSCs expressed high levels of neural markers, ionic channel markers, which are important in neural function, and tetrodotoxin-sensitive voltage-dependent sodium currents. After transplantation into the scala tympani of damaged cochlea, NI-hMSCs-injected animals exhibited a significant increase in the number of SGNs compared to Hanks balanced salt solution-injected animals. Transplanted NI-hMSCs were found within the perilymphatic space, the organ of Corti, along the cochlear nerve fibers, and in the spiral ganglion. Furthermore, the grafted NI-hMSCs migrated into the spiral ganglion where they expressed the neuron-specific marker, NeuN. CONCLUSION: The results show the potential of NI-hMSCs to give rise to replace the lost cochlear cells in hearing loss mammals.
Animals ; Bone Marrow ; Cell Differentiation ; Cochlea ; Cochlear Nerve ; Colforsin ; Ear ; Fibroblast Growth Factor 2 ; Guinea Pigs* ; Hair ; Hearing Loss ; Hearing Loss, Sensorineural ; Humans ; Ion Channels ; Mammals ; Mastoid ; Mesenchymal Stromal Cells* ; Neomycin ; Neurons ; Organ of Corti ; Regeneration* ; Scala Tympani ; Sensory Receptor Cells ; Sodium ; Spiral Ganglion ; Transplantation ; Transplants

BACKGROUND/AIMS: We investigated the role of representative endoplasmic reticulum proteins, stromal interaction molecule 1 (STIM1), and store-operated calcium entry-associated regulatory factor (SARAF) in pacemaker activity in cultured interstitial cells of Cajal (ICCs) isolated from mouse small intestine. METHODS: The whole-cell patch clamp technique applied for intracellular calcium ions ([Ca²+]i) analysis with STIM1 or SARAF overexpressed cultured ICCs from mouse small intestine. RESULTS: In the current-clamping mode, cultured ICCs displayed spontaneous pacemaker potentials. External carbachol exposure produced tonic membrane depolarization in the current-clamp mode, which recovered within a few seconds into normal pacemaker potentials. In STIM1-overexpressing cultured ICCs pacemaker potential frequency was increased, and in SARAF-overexpressing ICCs pacemaker potential frequency was strongly inhibited. The application of gadolinium (a non-selective cation channel inhibitor) or a Ca2+-free solution to understand Orai channel involvement abolished the generation of pacemaker potentials. When recording intracellular Ca²+ concentration with Fluo 3-AM, STIM1-overexpressing ICCs showed an increased number of spontaneous intracellular Ca²+ oscillations. However, SARAF-overexpressing ICCs showed fewer spontaneous intracellular Ca2+ oscillations. CONCLUSION: Endoplasmic reticulum proteins modulated the frequency of pacemaker activity in ICCs, and levels of STIM1 and SARAF may determine slow wave patterns in the gastrointestinal tract.
Animals ; Calcium ; Carbachol ; Endoplasmic Reticulum ; Gadolinium ; Gastrointestinal Motility ; Gastrointestinal Tract ; Interstitial Cells of Cajal ; Intestine, Small ; Ions ; Membranes ; Mice

Lubiprostone is a chloride (Cl-) channel activator derived from prostaglandin E1 and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid EP1, EP2, EP3, and EP4 antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [K+] channel blocker) and apamin (a calcium [Ca2+]-dependent K+ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive K+ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive K+ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive K+ channel through a prostanoid EP receptor-independent mechanism.
Alprostadil ; Animals ; Apamin ; Calcium ; Colon* ; Constipation ; Glyburide ; Interstitial Cells of Cajal* ; Membranes ; Mice* ; Muscle, Smooth ; Nitric Oxide ; Patch-Clamp Techniques ; Pinacidil ; Potassium ; Tetraethylammonium ; Lubiprostone

This study aimed to investigate the effect of pituitary adenylate cyclase-activating peptide (PACAP) on the pacemaker activity of interstitial cells of Cajal (ICC) in mouse colon and to identify the underlying mechanisms of PACAP action. Spontaneous pacemaker activity of colonic ICC and the effects of PACAP were studied using electrophysiological recordings. Exogenously applied PACAP induced hyperpolarization of the cell membrane and inhibited pacemaker frequency in a dose-dependent manner (from 0.1 nM to 100 nM). To investigate cyclic AMP (cAMP) involvement in the effects of PACAP on ICC, SQ-22536 (an inhibitor of adenylate cyclase) and cell-permeable 8-bromo-cAMP were used. SQ-22536 decreased the frequency of pacemaker potentials, and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. The effects of SQ-22536 on pacemaker potential frequency and membrane hyperpolarization were rescued by co-treatment with glibenclamide (an ATP-sensitive K+ channel blocker). However, neither N(G)-nitro-L-arginine methyl ester (L-NAME, a competitive inhibitor of NO synthase) nor 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) had any effect on PACAP-induced activity. In conclusion, this study describes the effects of PACAP on ICC in the mouse colon. PACAP inhibited the pacemaker activity of ICC by acting through ATP-sensitive K+ channels. These results provide evidence of a physiological role for PACAP in regulating gastrointestinal (GI) motility through the modulation of ICC activity.
8-Bromo Cyclic Adenosine Monophosphate ; Animals ; Cell Membrane ; Colon* ; Cyclic AMP ; Glyburide ; Interstitial Cells of Cajal* ; Membranes ; Mice ; NG-Nitroarginine Methyl Ester ; Pituitary Adenylate Cyclase-Activating Polypeptide*