• Title/Summary/Keyword: Epithelial transport

Search Result 72, Processing Time 0.033 seconds

Electron Microscopic Studies on Cellular Characteristics and Transport Systems in Tight Epithelia (Tight epithelia의 세포특성과 수송체계에 관한 전자현미경적 연구)

  • Jeon, Jin-Seok
    • Applied Microscopy
    • /
    • v.26 no.1
    • /
    • pp.47-57
    • /
    • 1996
  • This study analysed the transport properties of bladder mucosa known as the typical system of 'tight epithelia' by using TEM observation with both rapid freeze-fracture electron microscopy and thin-section method and mainly analysed the cellular characteristics of turtle bladder epithelial cells. The bladder epithelium, like other tight epithelia, consists of a heterogenous population of cells. The majority of the mucosal cells are the granular cells and may function primarily in the process of active $Na^+$ reabsorption in turtle bladder. The remaining two types of cells are rich in mitochondria and is believed to be res-ponsible for a single major transport system, namely, $H^+$ transport by A-type of cell and urinary $HCO_{3}^-$ secretion by B-type of cell. As viewed in freeze-fracture electron micrograph, the tight junctions form a continuous tight seal around the epithelial cells, thus restricting diffusion in tight epithelia. In addition, the apical surface membranes have a population of rod-shaped intramembranous particles (IMPs). It is believed that these IMPs probably represent the components of the proton pump. However, it is likely that these characteristics of the apical transporter remain to be clarified in tight epithelial cells.

  • PDF

In vitro Nasal Cell Culture Systems for Drug Transport Studies

  • Cho, Hyun-Jong;Termsarasab, Ubonvan;Kim, Jung-Sun;Kim, Dae-Duk
    • Journal of Pharmaceutical Investigation
    • /
    • v.40 no.6
    • /
    • pp.321-332
    • /
    • 2010
  • Growing interest in the nasal route as a drug delivery system calls for a reliable in vitro model which is crucial for efficiently evaluating drug transport through the nasal cells. Various in vitro cell culture systems has thus been developed to displace the ex vivo excised nasal tissue and in vivo animal models. Due to species difference, results from animal studies are not sufficient for estimating the drug absorption kinetics in humans. However, the difficulty in obtaining reliable human tissue source limits the use of primary culture of human nasal epithelial cells. This shortage of human nasal tissue has therefore prompted studies on the "passage" culture of nasal epithelial cells. A serially passaged primary human nasal epithelial cell monolayer system developed by the air-liquid interface (ALI) culture is known to promote the differentiation of cilia and mucin gene and maintain high TEER values. Recent studies on the in vitro nasal cell culture systems for drug transport studies are reviewed in this article.

Primary Culture of Human Nasal Epithelial Cell Monolayer for In Vitro Drug Transport Studies (약물의 in vitro 투과 실험을 위한 사람의 비강점막상피세포 단층막의 일차배양)

  • Yoo, Jin-Wook;Kim, Yoo-Sun;Lee, Min-Ki;Roh, Hwan-Jung;Lee, Chi-Ho;Kim, Dae-Duk
    • Journal of Pharmaceutical Investigation
    • /
    • v.32 no.1
    • /
    • pp.21-26
    • /
    • 2002
  • The primary culture of human nasal epithelial cell monolayer was performed on a Transwell. The effect of various factors on the tight junction formation was observed in order to develop an in vitro experimental system for nasal transport studies. Human nasal epithelial cells, collected from human normal inferior turbinates, were plated onto diverse inserts. After 4 days, media of the apical surface was removed for air-liquid interface (ALI) culture. Morphological characteristics was observed by transmission electron microscopy (TEM). A polyester membrane of $0.4\;{\mu}m$ pore size was determined as the most effective insert based on the change in the transepithelial electric resistance (TEER) value as well as the $^{14}C-mannitol$ transport study. The ALI method was effective in developing the tight junction as observed in the further increase in the TEER value and reduction in the permeability coefficient $(P_{app})$ of $^{14}C-mannitol$ transport. Results of the transport study of a model drug, budesonide, showed that the primary culture system developed in this study could be further developed and applied for in vitro nasal transport studies.

Effect of Scutellaria Baicalensis Georgi Extraction (SbGE) on H2O2-induced Inhibition of Phosphate Transport in Renal Epithelial Cells (황금약침액(黃芩藥鍼液)이 신장상피세포(腎臟上皮細胞)에서의 H2O2에 의한 인산염(燐酸鹽) 운반(運搬)의 억제(抑制)에 미치는 영향(影響))

  • Cho, Eun-jin;Youn, Hyoun-min;Jang, Kyung-jeon;Song, Choon-bo;Ahn, Chang-beobm
    • Journal of Acupuncture Research
    • /
    • v.19 no.4
    • /
    • pp.190-199
    • /
    • 2002
  • Objective : This study was performed to determine if Scutellaria balicalensis Georgi extract (SbGE) prevents oxidant-induced membrane transport dysfunction in renal tubular cells. Methods : Membrane transport function was estimated by measuring $Na^+$-dependent inorganic phosphate transport in opossum kidney (OK) cells. $H_2O_2$ inhibited phosphate transport in a dose-dependent manner. Results : The inhibitory effect of $H_2O_2$ was significantly prevented SbGE over concentration range of 0.005-0.05%. $H_2O_2$ caused ATP depletion, which was prevented by SbGE. $H_2O_2$ induced the loss of mitochondrial function as evidenced by decreased MTT reduction and its effect was prevented by SbGE. The $H_2O_2$-induced inhibition of phosphate transport was not affected by a potent antioxidant DPPD, but the inhibition was prevented by an iron chelator deferoxamine, suggesting that $H_2O_2$ inhibits $Na^+$-dependent phosphate transport via an iron-dependent nonperoxidative mechanism in renal tubular cells. Conclusion : These data suggest that SbGE may exert the protective effect against oxidant-induced membrane transport dysfunction by a mechanism similar to iron chelators in renal epithelial cells. However, furher studies should be carried out to find the active ingredient(s) of SbGE that exerts the protective effect.

  • PDF

Transport of anti-allergic drugs across the passage cultured human nasal epithelial cell monolayer

  • Lin, Hongxia;Yoo, Jin-Wook;Lee, Chi-Ho;Kim, Dae-Duk
    • Proceedings of the PSK Conference
    • /
    • 2003.04a
    • /
    • pp.291.2-292
    • /
    • 2003
  • The purpose of this study was to investigate the transport characteristics of passage cultured l1uman nasal epithelial cell monolayers grown on Transwell@ inserts using liquid-covered culture (LCC) method. The monolayer of passage 2 and 3 exhibited tight barrier (TEER>1,000 ohmxcm$^2$) in 2-3 days after seeding. In the morphological studies by actin staining and SEM/TEM, the existence of tight junction was clearly observed. (omitted)

  • PDF

Hydrogen Peroxide-induced Alterations in Na+-phosphate Cotransport in Renal Epithelial Cells

  • Jung, Soon-Hee
    • Korean Journal of Clinical Laboratory Science
    • /
    • v.41 no.2
    • /
    • pp.83-92
    • /
    • 2009
  • This study was undertaken to examine the effect of oxidants on membrane transport function in renal epithelial cells. Hydrogen peroxide ($H_2O_2$) was used as a model oxidant and the membrane transport function was evaluated by measuring $Na^+$-dependent phosphate ($Na^+$-Pi) uptake in opossum kidney (OK) cells. $H_2O_2$ inhibited $Na^+$-Pi uptake in a dose-dependent manner. The oxidant also caused loss of cell viability in a dose-dependent fashion. However, the extent of inhibition of the uptake was larger than that in cell viability. $H_2O_2$ inhibited $Na^+$-dependent uptake without any effect on $Na^+$-independent uptake. $H_2O_2$-induced inhibition of $Na^+$-Pi uptake was prevented completely by catalase, dimethylthiourea, and deferoxamine, suggesting involvement of hydroxyl radical generated by an iron-dependent mechanism. In contrast, antioxidants Trolox, N,N'-diphenyl-p-phenylenediamine, and butylated hydroxyanisole did not affect the $H_2O_2$ inhibition. Kinetic analysis indicated that $H_2O_2$ decreased Vmax of $Na^+$-Pi uptake with no change in the Km value. Phosphonoformic acid binding assay did not show any difference between control and $H_2O_2$-treated cells. $H_2O_2$ also did not cause degradation of $Na^+$-Pi transporter protein. Reduction in $Na^+$-Pi uptake by $H_2O_2$ was associated with ATP depletion and direct inhibition of $Na^+$-$K^+$-ATPase activity. These results indicate that the effect of $H_2O_2$ on membrane transport function in OK cells is associated with reduction in functional $Na^+$-pump activity. In addition, the inhibitory effect of $H_2O_2$ was not associated with lipid peroxidation.

  • PDF