Biomedical subjects

Joo-Heon Yoon

Publications and source records attributed to Joo-Heon Yoon.

At least 19 recordsLinked to original sources

PubMed2007

Interleukin-1beta upregulates Na+-K+-2Cl- cotransporter in human middle ear epithelia.

Disruption of periciliary fluid homeostasis is the main pathogenesis of otitis media with effusion (OME), one of the most common childhood diseases. Although the underlying molecular mechanisms are unclear, it has been suggested that the altered functions of ion channels and transporters are involved in the fluid collection of middle ear cavity of OME patients. In the present study, we analyzed the effects of a major cytokine interleukin (IL)-1beta, which was known to be involved in the pathogenesis of OME, on Na(+)-K(+)-2Cl(-) cotransporter (NKCC) in human middle ear cells. Intracellular pH (pH(i)) was measured in primary cultures of normal human middle ear epithelial (NHMEE) cells using a double perfusion chamber, which enabled us to analyze the membrane-specific transporter activities. NKCC activities were estimated by the pH(i) reduction due to bumetanide-sensitive intracellular uptake of NH(4) (+). In NHMEE cells, NKCC activities were observed only in the basolateral membrane, and immunoblotting using specific antibodies revealed the expression of NKCC1. Interestingly, IL-1beta treatments augmented the basolateral NKCC activities and increased NKCC1 expression. In addition, IL-1beta treatments stimulated bumetanide-sensitive fluid transport across the NHMEE cell monolayers. Furthermore, an elevated NKCC1 expression was observed in middle ear cells from OME patients when compared to those from control individuals. The above results provide in vitro and in vivo evidence that the inflammatory cytokine IL-1beta upregulates NKCC1 in middle ear epithelial cells, which would be one of the important underlying mechanisms of excess fluid collection in OME patients.

Ammonium Chloride↗

PubMed2007

Life-style and environmental factors in the development of nasal NK/T-cell lymphoma: a case-control study in East Asia.

Cases of nasal NK/T-cell lymphoma (NKTCL) occur occasionally in Asian and Latin American countries but rarely in Western countries. The etiological role of life-style and environmental factors in nasal NKTCL was investigated. Five university hospitals in Japan and one each in Korea and China participated in this study; a total of 88 cases and 305 hospital controls were accrued during 2000-2005. The odds ratio (OR) of NKTCL obtained after adjustments of age, sex and country was 4.15 (95% confidence interval (CI), 1.74-9.87) for farmers, 2.81 (CI, 1.49-5.29) for producers of crops, 4.01 (CI, 1.99-8.09) for pesticide users, 11.65 (CI, 1.17-115.82) for residents near garbage burning plants, 2.95 (CI, 1.25-6.95) for former drinkers, and 0.49 (CI, 0.23-1.04) for current smokers. The ORs for crop producers, who minimized their exposure to pesticides by using gloves and glasses, and sprinkling downwind at the time of pesticide use, were 3.30 (95% CI, 1.28-8.54), 1.18 (95% CI, 0.11-12.13) and 2.20 (95% CI, 0.88-5.53), respectively, which were lower than those for producers who did not take these precautions. Exposure to pesticides and chemical solvents could be causative of NKTCL. Taken together, life-style and environmental factors might be risk factors for NKTCL.

Adult↗

PubMed2007

Expression and localization of surfactant proteins in human nasal epithelium.

Surfactant proteins (SPs), designated SP-A, SP-B, SP-C, and SP-D, play an important role in surfactant metabolism and host defense mechanisms in the lung. This study investigates expression of the different SP types in human nasal mucosa and cultured normal human nasal epithelial (NHNE) cells and whether the expression of SP mRNA is influenced by the degree of mucociliary differentiation. RT-PCR was performed with mRNA from cultured NHNE cells and nasal mucosa. Immunohistochemical staining for SPs was performed on nasal mucosa specimens. Western blot analysis was performed on cell lysates from cultured NHNE cells. SP-A2, SP-B, and SP-D mRNAs were expressed in normal NHNE cells and human nasal mucosa. SPs were localized in ciliated cells of the surface epithelium and serous acini of the submucosal glands. SP-A, SP-B, and SP-D proteins were expressed in cultured NHNE cells. The degree of mucociliary differentiation influenced expression of the SP gene. We demonstrate that SP-A, SP-B, and SP-D are expressed in human nasal mucosa and cultured NHNE cells. Further study of the functional role of SPs in the upper airway is required.

Cells, Cultured↗

PubMed2006

Growth inhibition and apoptosis by (-)-epicatechin gallate are mediated by cyclin D1 suppression in head and neck squamous carcinoma cells.

In recent studies, green tea components have been shown to induce cell growth arrest and apoptosis in head and neck squamous cell carcinoma (HNSCC) cells. In this report, we have investigated the effects of epicatechin gallate (ECG), one of the catechins in green tea, on anti-cancer activity in vitro. We found that cyclin D1 was highly expressed in HNSCC cells, and ECG suppressed 90% of cyclin D1 expression in SCC7 cells. We have also evaluated the effect of ECG on cell growth and apoptosis, showing that ECG (50 microM) exhibited a significant inhibition (50%) on the growth of SCC7 cells via G1 cell cycle arrest. ECG suppressed cyclin D1 in SCC7 cells in a dose- and time-dependent manner, and the suppression of the beta-catenin pathway by ECG is one of the mechanism to facilitate ECG-induced cell growth arrest. These results suggest that ECG has a potential usage as a chemopreventive agent in HNSCC.

Antineoplastic Agents↗

PubMed2006

Retropharyngeal lymph node metastasis from olfactory neuroblastoma: A report of two cases.

Olfactory neuroblastoma is a rare, malignant neoplasm arising from the olfactory epithelium. It has an aggressive biological behavior that is characterized by local recurrence, atypical distant metastasis, and poor long-term prognosis. The incidence of cervical lymph node metastasis in olfactory neuroblastoma is variable, and treatment modalities are controversial. Moreover, few reports have been published concerning retropharyngeal lymph node metastasis from olfactory neuroblastoma. We present two cases of olfactory neuroblastoma with retropharyngeal lymph node metastasis. In addition, we provided a review of the current literature regarding olfactory neuroblastoma and retropharyngeal lymph node metastasis from olfactory neuroblastoma.

Adult↗

PubMed2006

Dexamethasone increases fluid absorption via Na+/H+ exchanger (NHE) 3 activation in normal human middle ear epithelial cells.

The proper homeostasis of the liquid lining the surface of the middle ear cavity is vitally important for maintaining a fluid-free middle ear cavity. Disruption of this homeostasis leads to fluid collection in the middle ear cavity and results in otitis media with effusion. We demonstrated the molecular and functional expression of the Na+/H+ exchanger (NHE)s in normal human middle ear epithelial (NHMEE) cells. We also evaluated the role of NHEs in fluid absorption and the effect of dexamethasone on NHE function and NHE-dependent fluid absorption in NHMEE cells. Western blot analysis was performed for NHE1, -2, and -3 in NHMEE cells. The fluid absorption rate was measured after liquid application on the luminal surface of the cells. Intracellular pH (pHi) was measured using the pH-sensitive fluorescent probe bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-AM. NHE activity was determined as Na+-induced pHi recovery from an acid load achieved by luminal exposure to 40 mmol/l NH4Cl. NHE1, -2 and -3 were all expressed in the NHMEE cells. The pHi recovery rate was suppressed by inhibition of NHE2 and -3 with HOE694 at concentrations greater than 50 microM. Inhibition of NHE3 with 650 microM of HOE694 or S3226 significantly decreased the fluid absorption rate. Dexamethasone increased the Na+-induced pHi recovery rate which was reversed by the inhibition of NHE3 with 650 microM of HOE694. Dexamethasone treatment up-regulated NHE3 expression in a dose-dependent manner. The fluid absorption rate was increased by treatment with dexamethasone (10(-7) M) and reversed by the inhibition of NHE3. In summary, we have shown that NHE3 are involved in the regulation of both pHi and fluid absorption on the luminal surface of NHMEE cells. Dexamethasone stimulates NHE3 expression and NHE3-dependent fluid absorption in NHMEE cells. These findings provide a new insight into mechanisms that regulate periciliary fluid and the therapeutic mechanisms behind steroid treatment of otitis media with effusion.

Absorption↗

PubMed2006

15-Lipoxygenase-1 induced by interleukin-4 mediates apoptosis in oral cavity cancer cells.

It is unknown whether IL-4 induces apoptosis in oral cavity cancer (OCC) cells and, if so, what the mediator of this apoptosis is. Therefore, this study investigated whether apoptosis of OCC cells is induced by IL-4 and whether 15-lipoxygenase-1 (15-LO-1), induced by IL-4, is the mediator of this apoptosis. SCC 1483 oral cavity cancer cells were used in these experiments, and flow cytometry and PARP cleavage were used to examine apoptosis. At an IL-4 dosage that inhibited 50% of cell proliferation, apoptosis was observed, and this apoptosis was inhibited by 2.2 microM caffeic acid (CA). 15-LO-1 mRNA expression was observed beginning at 8 h after treatment with IL-4, and apoptosis increased after 24 h treatment with IL-4. In this apoptosis, the caspase cascade was not involved. In summary, IL-4 induced apoptosis in SCC 1483 OCC cells, and 15-LO-1, induced by IL-4, may mediate this apoptotic pathway.

Apoptosis↗

PubMed2006

Surgical anatomy of the middle turbinate.

Clinicians have encountered many variations of the middle turbinate. Previous descriptions of the middle turbinate were only focused on its size and shape and lacked surgical implications associated with endoscopic sinus surgery. Therefore, the aim of this study was to examine the surgical anatomy of the middle turbinate in hemisected cadaveric heads. The middle turbinates from 101 hemisections of adult Korean cadaveric heads were measured using digital calipers and a protractor. The middle turbinates were then classified according to their shape. The mean distance between the anterior attachment of the middle turbinate and the anterior attachment of the superior turbinate was 18.5 mm. The posterior end of the middle turbinate extended more posteriorly than that of the inferior turbinate in 40% of the cases, while in 26.3% of the cases, the posterior end of the inferior turbinate extended more posteriorly than that of the middle turbinate. The middle turbinate was classified into three types according to the shape of its anterior border. In type 1, the anterior border of the middle turbinate ran directly posteroinferiorly from its attachment to the conchal plate, and was observed in 45.3% of the cases. In type 2, the anterior border of the middle turbinate initially coursed inferiorly from the conchal plate and then turned in a posteroinferior direction. This type was observed in 44.2% of the cases. Type 3 involved 10.5% of the cases where the anterior border bulged anteriorly before it coursed posteroinferiorly. The information provided in this report should assist surgeons when performing partial middle turbinectomies.

Adult↗

PubMed2006

Comparison of frontal pneumatization patterns between Koreans and Caucasians.

OBJECTIVE: To evaluate the prevalence of specific frontal recess cells in Korean and Caucasian populations; to evaluate and compare the relationship between anterior skull base length and frontal recess pneumatization in these two populations. MATERIALS AND METHODS: Frontal recess anatomy was studied with high resolution sinus CT scans obtained in 60 Korean adults and 41 Caucasian adults. None of the subjects had a history of frontal sinus disease or trauma. The anterior cranial base length (ACBL, distance between the nasion and center of the pituitary fossa) and anterior ethmoid length (AEL, distance between the nasion and upper attachment of basal lamella) was also measured on each side. RESULTS: Supraorbital ethmoid cells were more common in Caucasians whereas suprabullar cells and recessus terminalis were more common in Koreans. The prevalence of some frontal recess pneumatization patterns (specifically supraorbital ethmoid cell, suprabullar cell, and recessus terminalis) were more commonly associated with race rather than with ACBL or AEL. CONCLUSION: Frontal recess pneumatization patterns differ in the Korean and Caucasian adult populations. Because corresponding differences in skull base length were not identified, these differences seem likely to reflect other factors. Such information has clinical significance for frontal recess surgery in these patient populations.

Adult↗

PubMed2006

Effects of prostagladin E(2) on gel-forming mucin secretion in normal human nasal epithelial cells.

CONCLUSION: The findings of this study indicate that prostaglandin E(2) (PGE(2)) induces MUC5AC gene expression and mucin secretion via the EP4 receptor in cultured normal human nasal epithelial cells. OBJECTIVES: Recently, PGE(2) was found to induce MUC5AC production via an agonist of EP2/EP4, but not EP1/EP3, in normal human airway epithelium. However, the receptor that mediates MUC5AC has not been determined. This study aimed to investigate the MUC5AC mucin gene and mucin secretion by PGE(2) and its receptors in cultured normal human nasal epithelial cells. METHODS: After treatment with PGE(2) and/or PGE(2) antagonist, gel-forming mucin mRNA expression was determined by reverse transcription-polymerase chain reaction. Total mucin and MUC5AC mucin levels were measured using an immuno-dot blotting assay. RESULTS: PGE(2) increased only MUC5AC gene expression and MUC5AC mucin, but not expression of other gel-forming mucin genes. An EP2 receptor antagonist (AH 6809) did not suppress the PGE(2)-induced MUC5AC gene expression or MUC5AC mucin. However, an EP4 receptor antagonist (AH23848) significantly suppressed the level of PGE(2)-induced MUC5AC gene expression and MUC5AC mucin.

Cell Culture Techniques↗

PubMed2006

Particle image velocimetry measurements for the study of nasal airflow.

CONCLUSIONS: Particle image velocimetry (PIV) permits investigation of the distribution and velocity of the airflow in the nasal cavity. During breathing, the main laminar flow stream passes through the middle meatus and turbulent flow can be detected under physiologic conditions. OBJECTIVES: Physical models or casts of the nasal cavity have been utilized in several studies in an effort to understand its aerodynamics. PIV is a new technique for measuring the aerodynamic properties of tubular structures. In this article we evaluate nasal airflow characteristics during physiologic breathing under normal conditions and the usefulness of PIV. MATERIAL AND METHODS: A nasal model cast obtained by a combination of rapid prototyping and solidification of clear silicone was connected to a pump which simulated the physiological pressure in the upper airway system. A glycerol-water mixture was used as the flow material. The airstream was marked with spherical polyvinyl particles, observed through solidified clear silicone and analyzed using PIV. RESULTS: The main flow within the cavity, which was mostly laminar, passed through the middle meatus. Turbulence was clearly visible in the anteroinferior part of the middle turbinate. The flow rate was highest at the middle meatus during inspiration and expiration.

Airway Resistance↗

PubMed2006

Bacteriological findings and antimicrobial susceptibility in chronic sinusitis with nasal polyp.

CONCLUSIONS: We recommend amoxacillin/clavulanate, cephalosporins and macrolides rather than penicillin as the first-line drug in chronic sinusitis with nasal polyps. In cases where there is no improvement of symptoms, cultures should be taken from the middle meatus, followed by appropriate selection of second-line antibiotics according to the sensitivity test results. OBJECTIVE: To investigate the causative bacteria and the antimicrobial susceptibility in patients with chronic sinusitis and nasal polyps in Korea. MATERIALS AND METHODS: The bacteriology and antimicrobial susceptibility of maxillary sinus aspirates from 81 patients were evaluated. RESULTS: Aerobes were isolated from 58.0% of the cultures from the middle meatus and from 48.1% of those from the maxillary sinus. Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae were the most prevalent aerobic pathogens. Anaerobes were isolated from 8.6% of the cultures from the middle meatus and from 18.5% of the cultures from the maxillary sinus. The predominant anaerobic organisms were Prevotella and Peptostreptococcus in adults but none of them were cultured in children. A high rate of concordance of the middle meatus and maxillary sinus was noted. Monomicrobial infection was most commonly observed. Ampicillin-resistant H. influenzae isolates were cultured in 46% of the cases. Penicillin resistance rates were 93% for Staph. aureus; 25% of Strep. pneumoniae were intermediate and 25% were resistant.

Adolescent↗

PubMed2006

Use of PLGA scaffold for mucociliary epithelium transfer in airway reconstruction: a preliminary study.

CONCLUSION: A PLGA biodegradable membrane can be used as a scaffold for mucociliary epithelium transfer. OBJECTIVES: The aim of this study was to examine the usefulness of the PLGA membrane as a biodegradable scaffold for mucociliary epithelium transfer in order for it to be used as a substitute for a skin graft for restoring mucosal defects in the airway. METHODS: A PLGA biodegradable membrane was synthesized using the immersion precipitation method, and morphologic characterization was carried out using scanning electron microscopy (SEM). The degradation test was performed by soaking the PLGA membrane in a culture medium, and the morphological changes were observed by SEM. Human nasal basal epithelial (HNBE) cells were cultured on the newly synthesized PLGA membrane, and the morphological changes were analyzed using SEM. The MUC5AC and MUC8 mRNA levels were analyzed by RT-PCR. RESULTS: The PLGA membrane for the mucociliary epithelium transfer was successfully fabricated. It had a 24 mm diameter, a 50 microm thickness, and many pores with diameters of approximately 3 microm. The PLGA membrane began to degrade from 7 days after it was soaked in the culture medium. It rapidly degraded from 3 weeks and severe destruction of the pore structure was noted from 4 to 6 weeks of soaking. The HNBE cells were well differentiated into the mucociliary epithelium on the PLGA membrane both phenotypically and genotypically.

Absorbable Implants↗

PubMed2006

Expression and regulation of PLUNC in human nasal epithelium.

CONCLUSIONS: We demonstrated that PLUNC (palate, lung, and nasal epithelium clone) is secreted from nasal epithelial cells and is not influenced by differentiation or proinflammatory mediators. The functional role of PLUNC in the human airway has yet to be elucidated. OBJECTIVES: The localization and regulation of PLUNC protein in human nasal epithelium was investigated. First, we located epithelial cells expressing PLUNC protein in human nasal mucosa. Secondly, we sought to identify PLUNC protein in either human nasal secretions from healthy volunteers or apical secretions from cultured human nasal epithelial cells. Lastly, we investigated whether epithelial differentiation and proinflammatory cytokines influence the expression of PLUNC in human nasal epithelial cells. MATERIALS AND METHODS: Immunohistochemical staining for PLUNC was conducted on nasal turbinate specimens. Western blot analysis was conducted on nasal secretions from healthy volunteers, apical secretion from cultured human nasal epithelium, and on normal-appearing posterior ethmoid mucosa, inferior turbinate, and nasal polyp specimens. Reverse transcription-PCR (RT-PCR) of PLUNC was performed with mRNA from cultured human nasal epithelium cells treated with either interleukin-1beta or tumor necrosis factor-alpha. RESULTS: PLUNC was expressed in ciliated cells of surface epithelium and serous cells of the submucosal gland in the human nasal mucosa, and was also found in the nasal secretions of healthy volunteers and apical secretions of cultured human nasal epithelial cells. The degree of mucociliary differentiation and proinflammatory mediators did not influence the expression of PLUNC gene and protein in nasal epithelium.

Blotting, Western↗

PubMed2005

Nonclassical action of retinoic acid on the activation of the cAMP response element-binding protein in normal human bronchial epithelial cells.

Vitamin A (retinol) is essential for normal regulation of cell growth and differentiation. We have shown that the retinol metabolite retinoic acid (RA) induces mucous cell differentiation of normal human tracheobronchial epithelial (NHTBE) cells. However, early biological effects of RA in the differentiation of bronchial epithelia are largely unknown. Here, we showed that RA rapidly activated cAMP response element-binding protein (CREB). However, RA did not use the conventional retinoic acid receptor (RAR)/retinoid X receptor (RXR) to activate CREB. RA activated CREB in NHTBE and H1734 cells in which RARs/RXR were silenced with small interfering RNA (siRNA) targeting RAR/RXR expression or deactivated by antagonist. Inhibition of protein kinase C (PKC) or extracellular regulated kinase (ERK1/2) blocked the RA-mediated activation of CREB. In addition, depletion of p90 ribosomal S6 kinase (RSK) via siRSK1/2 completely abolished the activation, suggesting that PKC, ERK, and RSK are required for the activation. Altogether, this study provides the first evidence that RA rapidly activates CREB transcription factor via PKC, ERK, and RSK in a retinoid receptor-independent manner in normal bronchial epithelial cells. This noncanonical RA signaling pathway may play an important role in mediating early biological effects in the mucociliary differentiation of bronchial epithelia.

Bronchi↗

PubMed2005

Molecular targets of dietary polyphenols with anti-inflammatory properties.

There is persuasive epidemiological and experimental evidence that dietary polyphenols have anti-inflammatory activity. Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) have long been used to combat inflammation. Recently, cyclooxygenase (COX) inhibitors have been developed and recommended for treatment of rheumatoid arthritis (RA) and osteoarthritis (OA). However, two COX inhibitors have been withdrawn from the market due to unexpected side effects. Because conventional therapeutic and surgical approaches have not been able to fully control the incidence and outcome of many inflammatory diseases, there is an urgent need to find safer compounds and to develop mechanism-based approaches for the management of these diseases. Polyphenols are found in many dietary plant products, including fruits, vegetables, beverages, herbs, and spices. Several of these compounds have been found to inhibit the inflammation process as well as tumorigenesis in experimental animals; they can also exhibit potent biological properties. In addition, epidemiological studies have indicated that populations who consume foods rich in specific polyphenols have lower incidences of inflammatory disease. This paper provides an overview of the research approaches that can be used to unravel the biology and health effects of polyphenols. Polyphenols have diverse biological effects, however, this review will focus on some of the pivotal molecular targets that directly affect the inflammation process.

Animals↗

PubMed2005

ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells.

Ion channels, such as the epithelial sodium channel (ENaC), are essential for maintaining a fluid-free middle ear cavity by controlling periciliary fluid. Deviations from the normal volume or compositions of periciliary fluid are probably responsible for otitis media with effusion. To elucidate the physiologic roles of the ENaC and cystic fibrosis transmembrane conductance regulator (CFTR) in the middle ear mucosa, we compared the electrophysiological activity and protein expressions of ENaC and CFTR in normal human middle ear epithelial (NHMEE) cells with those in normal human nasal epithelial (NHNE) cells. We also evaluated the role of ENaC and CFTR in fluid transport by NHMEE cells. Short-circuit current (Isc) was measured in cell monolayers by modified Ussing chambers. Immunoblotting was performed for ENaC and CFTR. In addition, transepithelial fluid transport was measured after loading 100 microl of fluid onto the luminal cell surface. The amiloride-sensitive Isc in NHMEE cells was much larger than in NHNE cells, whereas the forskolin-induced Isc, presumably mediated by CFTR, was significantly smaller in NHMEE cells. ENaC subunits alpha, beta, and gamma were all detected in NHMEE cells, and their expressions were stronger than those in NHNE cells. In comparison, CFTR was also detected in the middle ear mucosa, but at a lower expression level than in NHNE cells. NHMEE cells showed more amiloride-sensitive fluid absorption than NHNE cells. In contrast, fluid absorption was less sensitive to forskolin/IBMX in NHMEE cells than in NHNE cells. The ATP induced Cl- efflux and the amplitude of ATP-induced current in NHMEE cells was much larger than in NHNE cells. In the present study, we have demonstrated an enhanced amiloride-sensitive Isc and fluid absorption in NHMEE cells, where the role of CFTR is limited. Our data also suggest that the ATP-induced Cl- channel could be an alternative Cl- channel to CFTR in NHMEE cells.

1-Methyl-3-isobutylxanthine↗

PubMed2005

P2Y2 agonist induces mucin secretion via Ca2+- and inositol 1,4,5-triphosphate-dependent pathway in human middle ear epithelial cells.

Purinergic agonists regulate mucin secretion in the airway epithelial cells. This study examined the effects of the apical application of purinergic agonists on Ca(2+) influx ([Ca(2+)](i)), and mucin secretion along with their underlying signaling pathway in normal human middle ear epithelial (NHMEE) cells. The apical membrane of NHMEE cells were stimulated with various purinergic agonists, including UTP, and the [Ca(2+)](i) was measured using a miniature Ussing double perfusion chamber. P2Y(2) receptor in NHMEE cells was also localized by immunohistochemistry. UTP-induced mucin secretion was quantified by an immunoblotting assay. The order of the purinergic agonist potency with respect to [Ca(2+)](i) determined in this study was ATP = UTP > 2-MeSATP > UDP >> adenosine which is consistent with that obtained from P2Y(2) receptor activation. The P2Y(2) receptor is expressed in the apical membrane of monolayered cultured NHMEE cells. Apical UTP-induced [Ca(2+)](i) was inhibited by 2-aminoethoxydiphenyl borate (2-APB) but not by ryanodine. UTP-induced mucin secretion was inhibited by a Ca(2+) chelating agent, BAPTA-AM, and was stimulated by ionomycin. UTP-induced mucin secretion was also suppressed by U73122 and 2-APB, while Calphostin C suppressed it to a small extent and PD98059 was ineffective. Caffeine also inhibited the UTP-induced [Ca(2+)](i) and mucin secretion. These results suggest that the P2Y(2) receptor is expressed in NHMEE cells, and plays a major role in modulating the [Ca(2+)](i) from the IP(3)-sensitive intracellular Ca(2+) store. UTP-induced mucin secretion in NHMEE cells is strongly dependent on Ca(2+)- and IP(3).

Calcium↗