Effects of Chlorhexidine Diacetate on Ruminal Microorganisms

The objectives of this study were to examine the effects of chlorhexidine diacetate on growth and L-lactate production by Streptococcus bovis JB1 as well as the effects of this antimicrobial compound on the mixed ruminal microorganism fermentation. Addition of 1.8 μM chlorhexidine diacetate to glucose medium resulted in a lag in growth by S. bovis JB1, and growth was completely inhibited in the presence of 3.6, 9.0, and 18 μM chlorhexidine. When 6.2 μM chlorhexidine diacetate was added to glucose medium after 2 h of incubation, glucose utilization and L-lactate production by S. bovis JB1 were reduced. Phosphoenolpyruvate-dependent phosphorylation of ¹⁴C-glucose by toluene-treated cells of S. bovis JB1 was inhibited by increasing concentrations (1.8 to 18 μM) of chlorhexidine, whereas only the 18 μM concentration reduced the membrane potential (ΔΨ). Chlorhexidine diacetate was a potent inhibitor of L-lactate and methane production from glucose fermentation by mixed ruminal microorganisms. However, because chlorhexidine also decreased acetate and propionate concentrations and increased ammonia concentrations in mixed-culture incubations, this antimicrobial compound may have limited application as a ruminant feed additive. Received: 4 November 1997 / Accepted: 22 December 1997     

Pentavalent Vanadium at Concentration of the Underground Water Level Enhances the Sweet Taste Sense to Glucose in College Students

Underground water in volcanic areas contains vanadium when the basalt layer exists among igneous rocks. The concentration of vanadium in drinking water sometimes exceeds 0.8 μM in these areas, however, the physiological effects of vanadium, especially non-toxic effects, at concentrations lower than 1 μM are unknown. In the present experiments, we examined the effect of pentavalent vanadium and tetravalent vanadium at 0.8 and 8.0 μM concentrations on the recognition threshold to taste substances in healthy college students. Pentavalent vanadium, ammonium vanadate, lowered the sweet taste threshold to glucose at 0.8 and 8.0 μM as well. Tetravalent vanadium, vanadium sulfate, did not alter the threshold to glucose either at 8.0 μM or at 0.8 μM. Ammonium vanadate also decreased the sweet taste threshold to l-proline at 8.0 μM. Ammonium vanadate did not influence the sour taste threshold to hydrogen chloride. Neither ammonium sulfate nor ammonium bicarbonate altered the sweet taste threshold to glucose. Therefore, the effect of ammonium vanadate on the sweet taste threshold is attained by vanadium but not by ammonium. It was concluded that pentavalent vanadium at 0.8 μM intensifies the sweet taste sense to glucose rather specifically. We have first shown the physiological effect of vanadium at the concentration of the underground water level.     

Allelopathy of red pine: isolation and identification of an allelopathic substance in red pine needles

Since red pine (Pinus densiflora Sieb. et Zucc.) often forms sparse forest floors where herbaceous plants do not grow well, allelopathy of red pine was investigated. A growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as abscisic acid-β-d-glucopyranosyl ester (ABA-GE). This substance inhibited root and shoot growth of cress and E. crus-galli seedlings at concentrations greater than 0.1 μM. The concentrations required for 50% growth inhibition on roots and shoots of cress were 0.23 and 0.61 μM, respectively, and those of E. crus-galli were 1.1 and 2.8 μM, respectively. The activity of ABA-β-d-glucosidase, which liberates free ABA from ABA-GE, in cress and E. crus-galli seedlings was 13–29 nmol mg⁻¹ protein min⁻¹. Endogenous concentration of ABA-GE in the pine needles was 4.1–21.5 μmol kg⁻¹ and the concentration in soil water of the pine forest was 2.5 μM. The effectiveness of ABA-GE on growth inhibition and the occurrence of ABA-GE in pine needles and soil water suggest ABA-GE may play an important role in the allelopathy of red pine resulting in the formation of sparse forest floors.     

Effect of dDAVP on basolateral cell surface water permeability in the outer medullary collecting duct

We report a novel approach for assessing the volume of living cells which allows quantitative, high-resolution characterization of dynamic changes in cell volume while retaining the cell functionality. The aim of this study was to evaluate the short-term effect of vasopressin on basolateral cell surface water permeability in the outer medullary collecting duct (OMCD). The permeability of the basolateral cell membrane was determined in the tubules where the apical membrane was blocked with oil injected into the lumen. The apparent coefficient of water permeability (P _f) was evaluated by measuring the cell swelling after the step from hypertonic to isotonic medium (600 mosm to 300 mosm). Desmopressin (dDAVP) induced an increase of the basolateral P _f from 113.7±8.5 μm/s in control cells to 186.6±11.4 μm/s in micro-dissected fragments of the OMCD incubated in vitro (10⁻⁷ M dDAVP, 30 min at 37 °C) (P<0.05). Mercury caused pronounced inhibition of basolateral water permeability (26.0±6.9 μm/s; P<0.05). The effect of mercury (1.0 mM HgCl₂) was reversible: after washing the fragments with PBS for 20 min, P _f values were restored to the control levels (125.0±9.5 μm/s). The results of the study indicate the existence of a mechanism controlling the osmotic water permeability of the basolateral cell membrane in the OMCD epithelium.     

Potentiation of Regulatory Volume Decrease by a P2-Like Receptor and Arachidonic Acid in American Alligator Erythrocytes

This study examined the role of a P2 receptor and arachidonic acid (AA) in regulatory volume decrease (RVD) by American alligator red blood cells (RBCs). Osmotic fragility was determined optically, mean cell volume was measured by electronic sizing, and changes in intracellular Ca²⁺ concentration were visualized using fluorescence microscopy. Gadolinium (50 μM), hexokinase (2.5 U/ml), and suramin (100 μM) increased osmotic fragility, blocked volume recovery after hypotonic shock, and prevented a rise in intracellular Ca²⁺ that normally occurs during cell swelling. The P2X antagonists PPADS (50 μM) and TNP-ATP (10 μM) also increased fragility and inhibited volume recovery. In contrast, ATPγS (10 μM), α,β-methylene-ATP (50 μM) and Bz-ATP (50 μM) had the opposite effect, whereas 2-methylthio-ATP (50 μM) and UTP (10 μM) had no effect. In addition, the phospholipase A₂ (PLA₂) inhibitors ONO-RS-082 (10 μM), chlorpromazine (10 μM), and isotetrandrine (10 μM) increased osmotic fragility and blocked volume recovery, whereas AA (10 μM) and its nonhydrolyzable analog eicosatetraynoic acid (ETYA, 10 μM) had the reverse effect. Further, AA (10 μM), but not ATPγS (10 μM), prevented the inhibitory effect of a low Ca²⁺-EGTA Ringer on RVD, whereas both AA (10 μM) and ATPγS (10 μM) caused cell shrinkage under isosmotic conditions. In conclusion, our results are consistent with the presence of a P2-like receptor whose activation stimulated RVD. In addition, AA also was important for volume recovery.     

Melittin-induced membrane permeability: A nonosmotic mechanism of cell death

Summary Derived from honeybees, melittin is a 26-amino acid, α-helical, membrane-attack protein that efficiently kills mammalian cells. To investigate the contribution of colloid-osmotic effects to the mechanism of cell death, we studied the effect of melittin on lymphocyte membrane permeability and cell volumes. Melittin concentrations of 0.5 to 2.0 μM induced release of membrane permeability markers without total disruption of the cell membrane. At these melittin concentrations, electrical-impedance cytometry demonstrated melittin-induced changes in red blood cell volumes (P<0.01), but no change in lymphocyte cell volumes (P>0.05). Streaming video microscopy, obtaining images of melittintreated lymphocytes at 80-ms intervals, demonstrated a loss of optical density (P<0.001) suggesting a flattening of the cell but no significant increase in cell perimeter (P>0.05). Real-time multiparameter flow cytometry of melittin-treated lymphocytes confirmed simultaneous loss of the cytoplasmic marker, calcein, and uptake of the DNA dye, ethidium homodimer, but demonstrated no increase in forward light scatter. Transmission-electron microscopy of melittin-treated lymphocytes showed normal cell volumes but discontinuities in the cell membrane suggesting direct membrane toxicity. We conclude that melittin causes lymphocyte death by a “leaky patch” mechanism that is independent of colloid-osmotic effects.     

Factors defining the rate of oxygen uptake by the red blood cell

Using numerical methods, the initial rates of oxygen uptake by the red blood cell have been computed. The methods accommodate both a water layer and membrane which may act as diffusive impedance to gas influx. The differential solubilities of the gas in these two layers have also been incorporated in the methods. The presence of a 0.50–0.65 μm deoxygenated water layer has been calculated to simulate the experimental results by Roughton (1959). Experimental studies of CO and NO uptake by the red cell could also be simulated. Although a membrane-only model with given parameters can also account for the observed rates of oxygenation of the red cell (Weingardenet al., submitted for publication), the additional incorporation of differential solubilities of oxygen in the different layers of the RBC yields results that indicate a three layer model to be more plausible. Using a thin layer-red cell oxygenation system, the rates of oxygenation were determined for red cells surrounded by a 4.2 μm deoxygenated water layer. The rates were found to compare favorably to the results of the theoretical model.     

Temporal and spatial distributions of dissolved organic carbon and nitrogen in two small lakes on the Southwestern China Plateau

Temporal and spatial distributions of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), chlorophyll-a and inorganic nitrogen were investigated in two small mountainous lakes (Lake Hongfeng and Baihua), on the Southwestern China Plateau, based on almost 2 years’ field observation. DOC concentrations ranged from 163 μM to 248 μM in Lake Hongfeng and from 143 μM to 308 μM in Lake Baihua, respectively, during the study period. DON concentrations ranged from 7 μM to 26 μM in Lake Hongfeng and from 14 μM to 47 μM in Lake Baihua. DOC showed vertical heterogeneity with higher concentrations in the epilimnion than in the hypolimnion during the stratification period. The DON concentration profiles appeared to be more variable than the DOC profiles. Apparent DON maxima occurred in the upper layer of water. In Lake Hongfeng, DOC concentration in the surface water was highest at the end of spring and early summer. DON concentration was 2–5 μM higher in May 2003 and in June 2004 than in adjacent months. DOC and chlorophyll-a concentrations were significantly correlated (r = 0.79, P < 0.05). The period of highest concentrations of DOC in Lake Hongfeng was also the season of concentrated rainfall. Algae activity and allochthonous input might result in an increase of DOC and DON concentrations together. In Lake Baihua, the maximum concentrations of DOC and DON in the surface water occurred simultaneously in May 2003 and February 2004. DOC concentrations were significantly correlated with DON (r = 0.90, P < 0.01), indicating the common sources. Allochthonous input, biological processes, stratification and mixing were the most important factors controlling the distributions and cycling of dissolved organic matter (DOM) and inorganic nitrogen in these two lakes. Inference from the corresponding vertical distributions of DOM and inorganic nitrogen indicated that DOM played potential roles in the internal loading of nitrogen and metabolism in the water body in these small lakes. The carbon/nitrogen (C/N) ratio showed a potential significance for tracing the source and biogeochemical processes of DOM in the lakes. These results are of significance in the further understanding of biogeochemical cycling and environmental effects of DOM and nitrogen in lake ecosystems.     

Peroxidase activity and lignification in soybean root growth-inhibition by juglone

The changes in activities of soluble and cell wall-bound peroxidases and lignin contents in juglone-stressed soybean (Glycine max) seedlings and their relationships with root growth were investigated. Soybean seedlings (3-d-old) were cultivated in nutrient solution supplemented with 0.5 to 25 μM juglone for 24 h. Length and dry mass of roots decreased after 5 to 25 μM juglone treatments. Low juglone concentrations (≤ 1 μM) increased soluble peroxidase activity, while high concentrations (≥ 10 μM) inhibited activities of soluble and cell wall-bound peroxidases. Juglone (≤ 1 μM) did not affect lignin content but highly increased lignification after 5 to 25 μM treatments. Results indicate that lignification may be an important step in root growth reduction of juglone-stressed soybean.     

The chemoluminescence of the primary focus of a suppurative infection and of isolated neutrophils exposed to dimephosphon]

The influence of dimephosphone at concentrations of 0.001 M-0.75 M on the chemiluminescence of tissues at the focus of purulent infection in the ear of a guinea pig, on the survival rate of the experimental animals injected with the lethal dose of Staphylococcus aureus, as well as on the spontaneous and stimulated chemiluminescence of blood neutrophils in patients with wound infection, was studied. The study showed that different concentrations of dimephosphone oppositely influenced the intensity of the chemiluminescence of neutrophil suspensions and tissues at the focus of infection: low concentrations were found to produce stimulating action and high concentrations, suppressive action. At the highest concentration used in this study (0.75 M) dimephosphone prevented the death of the animals receiving lethal doses of S. aureus.     

Effects of red cell permeability on transcapillary tracer transport: The case of negligible back diffusion

Estimates of capillary tracer permeability calculated using multiple indicator data depend upon the particular model adopted to describe blood tissue exchange. The model proposed by Crone (1963) is appropriate when some of the injected tracer diffuses into the tissue but does not return appreciably to the bloodstream before data collection is terminated. Under these conditions extraction of tracer by the tissue depends on a single dimensionless parameter, α_cap, defined as the ratio of capillary permeability surface area to water flow. The effects of finite red cell tracer permeability on the Crone model estimate of capillary permeability are examined in the present study. The results indicate that even when back diffusion from the extravascular space is negligible, significant errors in the Crone model estimate can be expected when capillary permeability is relatively high and the ratio of red cell to capillary permeability is less than unity. However, when an aliquot of blood is equilibrated with tracer prior to injection and the dimensionless capillary permeability is relatively low (i.e. α_cap ≦ 0.25 for a haematocrit≦50%), the whole blood Crone model estimate of α_cap will be within 10% of the actual value, irrespective of red cell permeability. Red cell-plasma exchange for commonly used tracer-organ combinations should not significantly affect Crone estimates of capillary permeability under normal physiological conditions, but may be important in low flow situations. Supported by Grant No. HL 19153 (SCOR in Pulmonary Vascular Diseases). This work was done during Dr. Roselli’s tenure as an NHLBI Training Grant Fellow (NHLBI Training Grant No. 07123).     

Seasonal variability of inorganic and organic nitrogen in the North Sea

This study considers the cycling of nitrogen in the waters of the North Sea, particularly focussing on organic nitrogen. Dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and particulate organic nitrogen (PON) were measured in the North Sea over a one-year period (autumn 2004–summer 2005). The surface water concentrations of nitrate, ammonium, DON and PON during the present study ranged from <0.1–7.2 μM, <0.1–2.0 μM, 1.9–11.2 μM and 0.3–5.6 μM, respectively, with DON the dominant fraction of total nitrogen at all times. These nutrients concentrations were significantly lower compared to previous studies in the southern North Sea. The seasonal variations showed high mean surface concentrations of nitrate (4.7 ± 0.6 μM) and DON (8.9 ± 0.9 μM), low ammonium (<0.1 μM) and PON (0.8 ± 0.1 μM) in winter, shifting to low nitrate (0.3 ± 0.3 μM) and DON (4.2 ± 1.2 μM) in summer, with high ammonium (0.8 ± 0.4 μM) in autumn and PON (2.5 ± 1.2 μM) in spring. Highest mean surface DON concentration was measured in winter and may be due to resuspension of the organic matter from the bottom sediments. For autumn and spring, phytoplankton DON release was likely to be the most significant source of DON as shown by high concentrations of low molecular weight (LMW) DON and its positive correlation to chlorophyll a. Low total and LMW DON concentrations during summer were likely to be due to the uptake of the LMW DON fraction by phytoplankton and bacteria and the stratification of the water column. DON is therefore shown to be a potentially important source of nitrogen in shelf seas especially after the spring bloom has depleted nitrate to limiting concentrations. Handling editor: L. Naselli-Flores     

Isolation and identification of potent allelopathic substances in rattail fescue

Aqueous methanol extracts of rattail fescue (Vulpia myuros) inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), Digitaria sanguinalis and Lolium multiflorum. Increasing the extract concentration increased the inhibition, suggesting that rattail fescue may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of rattail fescue was purified and two main inhibitory substances were isolated and identified by spectral data as (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol. Both substances inhibited root and shoot growth of cress at concentrations greater than 0.3 μM. The concentrations required for 50% growth inhibition on root and shoot growth of cress, lettuce, alfalfa, timothy, D. sanguinalis and L. multiflorum were 2.7–19.7 μM for (−)-3-hydroxy-β-ionone, and 2.1–34.5 μM for (+)-3-oxo-α-ionol. The concentration of (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol, respectively, in rattail fescue was 7.8 and 3.7 μg g⁻¹ fresh weight. Considering the endogenous level and the inhibitory activity, (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol may work as allelopathic substances in rattail fescue through the growth inhibition of neighboring plant species.     

Factors affecting the selenium intake of people in transbaikalian Russia

The selenium concentration in foods grown and consumed and in plasma, red blood cells, and toenails of people living in the district of Chita in the transbaikalian part of Russia were studied in August 1991. Preliminary results from the area have suggested low selenium intakes and the possible occurrence of cardiomyopathy (Keshan disease) in the population. A low selenium concentration in foods grown locally was found: mean selenium concentration in wheat grains was 1, 5, and 28 μg/kg, respectively, in three villages studied, that of oats was beween 3–6 μg/kg, and of cow's milk 10–27 μg/kg dry matter. The selenium concentration of bread was considerably higher, between 87–337 μg/kg dry wt, presumably because wheat imported from the US had been used for baking. Occasional samples of pork, beef, and mutton contained between 32–318 μg selenium/kg dry wt. Low selenium concentrations were observed in samples of soil and river water. The mean plasma selenium concentration of 52 persons was 1.02 μmol/L, including 33 children and 19 adult subjects. The selenium concentrations in red blood cells and toenails were 1.95 μmol/L and 0.61 mg/kg, respectively. No symptoms of heart disease caused by selenium deficiency were observed. It is concluded that the selenium status of people was fairly good thanks to the contribution to dietary intake of imported wheat with a high selenium content. As the selenium concentration was very low in foods grown in the area, the selenium intake of the population will be reduced to a very low level if only locally produced foods are consumed.     

The role of red blood cell adenylyl cyclase activation in changes of erythrocyte membrane microrheological properties

The ability of red blood cells (RBCs) for the reversible change of their shape under passing through capillaries in microcirculation mainly depends on membrane elasticity of these cells. Phosphorylation of some membrane proteins can result in the changes of microrheological red blood cell properties. Here we show a significant increase in RBC deformability (RBCD) after incubation with isoproterenol (10⁻⁶ M). Red blood cell aggregation (RBCA) decreased under these conditions only slightly. When forskolin (10 μM), an adenylyl cyclase (AC) stimulator, was added to the RBC suspension, RBCD increased significantly (p < 0.05). Some more changes of deformability were found after incubation of RBC with stable penetrating analog of cyclic adenosine phosphate (cAMP), dibutyryl-cAMP, (dB-cAMP, 50 μM) and after phosphodiesterase (PDE) activity inhibition with Vinpocetine, Rolipram, or IBMX. It was found that Gs-proteins inhibitor Clonidine and specific Gi-protein stimulator Mastaparan 7 increased both RBCD and RBCA. On the whole, the data clearly show that the RBC aggregation and deformation changes are related with activation of the different intracellular signaling pathways. We suppose that RBCD increase was mainly associated with activation of the adenylyl-cyclase-cAMP system.     

Genistein inhibits the contact-stimulated migration of prostate cancer cells

The results of several epidemiological studies have suggested that a soybean-based diet is associated with a lower risk of prostate cancer. We investigated the effect of the soy isoflavone genistein on the proliferation and contact-stimulated migration of rat prostatic carcinoma MAT-LyLu and AT-2 cell lines. Genistein almost completely inhibited the growth of both MAT-LyLu and AT-2 cells in the concentration range from 25 to 100 μM, but the addition of 1 μM genistein to the medium significantly stimulated the proliferation of both cell lines. Additionally, at concentrations above 25 μM, genistein showed a potent cytotoxic effect. However, the central finding of this study is that at physiologically relevant concentrations (1 μM and 10 μM), genistein inhibits the motility of prostate cancer cells stimulated by homo-and heterotypic contacts. These results show that at physiological concentrations, genistein exerts an inhibitory effect on the migration of prostate cancer cells and suggest that it may be one of the factors responsible for the anti-metastatic activity of plant isoflavonoids     

Cytotoxic, immunosuppressive and trypanocidal activities of agrocybin, a polyacetylene produced by Agrocybe perfecta (Basidiomycota)

Summary The ethyl acetate extract from the culture of the fungus Agrocybe perfecta (Rick) Singer was selected for further study in a screening of Brazilian basidiomycetes for bioactivity. The extract showed significant activity against the recombinant enzyme trypanothione reductase (TryR) from Trypanosoma cruzi, lymphocyte proliferation in human peripheral mononuclear cells (PBMC) stimulated with phytohemaglutinin (PHA), and the human cancer cell lines UACC-62 (melanoma), MCF-7 (mammary), and TK-10 (kidney). The chromatographic fractionation of the extract was monitored by the above bioassays and showed that agrocybin was the active component. Agrocybin, a known polyacetylene amide, showed an IC₅₀ of 2 μM in the TryR assay but killed only 60% of the trypomastigote form of T. cruzi in infected murine blood even at 680 μM. This weaker activity could be due to the low temperature used to mimic banked blood or as a consequence of its inactivation by blood, already reported in the literature. On the other hand, it inhibited the proliferation of PBMC by 50% at 3.4 μM and the growth of the cancer cell lines at concentrations between 9 and 24.5 μM. Measurements of DNA fragmentation using flow cytometry suggest that agrocybin promotes cell death via apoptosis.     

Cadmium and mercury cause an oxidative stress-induced endothelial dysfunction

We investigated the ability of cadmium and mercury ions to cause endothelial dysfunction in bovine pulmonary artery endothelial cell monolayers. Exposure of monolayers for 48 h to metal concentrations greater than 3–5 μM produced profound cytotoxicity (increased lactate dehydrogenase leakage), a permeability barrier failure, depletion of glutathione and ATP and almost complete inhibition of the activity of key thiol enzymes, glucose-6-phosphate dehydrogenase (G6PDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In contrast, metal concentrations less than 1–2 μM induced increases in glutathione and thiol-enzyme activities with minimal changes in LDH leakage, barrier function and ATP content. At shorter incubation times (24 h or less), high concentrations of cadmium caused glutathione induction rather than depletion. Thus, oxidative stress and cytotoxicity induced by lower concentrations of the metal ions stimulate compensatory responses, including increased synthesis of glutathione, which presumably preserved the activity of key thiol enzymes, however these responses were not sustainable at higher metal ion concentrations. We conclude, while high concentrations of heavy metals are cytotoxic, lower concentration induce a compensatory protective response, which may explain threshold effects in metal-ion toxicity.     

The effect of oxidative stress on the production of the recombinant protein, interferon γ, produced by Chinese hamster ovary cells in stirred-batch culture

The CHO320 cell line, engineered to produce human interferon γ was investigated with regard to its susceptibility to oxidative stress. Batch cultures of the cells grown in a bench-top bioreactor exhibited no marked response to changes in oxygen concentration between 6% and 14% whereas cell growth and recombinant protein production were inhibited by increasing the oxygen to 20%. High concentrations of hydrogen peroxide (in excess of 200 μM) were required to inhibit growth of the CHO320 cells whereas concentrations of 50 μm and 100 μM had no effect on recombinant protein production. Buthionine sulphoximine (50 μM and 100 μM) completely depleted the cells of glutathione within 24 h; however, no quantitative effect on recombinant protein production was seen. It is concluded that the CHO320 cells are, possibly as a consequence of the long selection process they have undergone, very resistant to oxidative stress. Received: 14 November 1996 / Received last revision: 14 April 1997 / Accepted: 19 April 1997     

Docosahexaenoic acid and eicosapentaenoic acid-enriched phosphatidylcholine liposomes enhance the permeability, transportation and uptake of phospholipids in Caco-2 cells

The influence of docosahexaenoic acid (DHA)- and eicosapentaenoic acid (EPA)-enriched phosphatidylcholine (PC) on the permeability, transport and uptake of phospholipids was evaluated in Caco-2 cells. The cells were grown on permeable polycarbonate transwell filters, thus allowing separate access to the apical and basolateral chambers. The monolayers of the cells were used to measure lucifer yellow permeability and transepithelial electrical resistance (TEER). Transcellular transportation of diphenylhexatriene (DPH) labeled-PC small unilamellar vesicles (SUV) from the apical to basolateral chamber, and uptake of the same SUV was monitored in the cell monolayers. Cell-membrane perturbation was evaluated to measure the release of lactate dehydrogenase and to determine the cell viability with sodium 2-(4-iodophenyl)-3-(4-nitrophenyl) -5-(2, 4-disulfophenyl)-2H-tetrazolium dye reduction assay. The lucifer yellow flux was 1.0 and 1.5 nmol/h/cm² with 50 μM PC, and 17.0 and 23.0 nmol/h/cm² with 100 μM PC when monolayers of Caco-2 cells were treated with DHA- and EPA-enriched PC, respectively. TEER decreased to 24 and 27% with 50 and 100 μM DHA-enriched PC, and to 25 and 30% with 50 and 100 μM EPA-enriched PC, respectively. Our results show that DHA- and EPA-enriched PC increases tight junction permeability across the Caco-2 cell monolayer whereas soy PC has no effect on tight junction permeability. Transportation and uptake of DHA- and EPA-enriched PC SUV differed significantly (P < 0.01) from those of soy PC SUV at all doses. We found that PC SUV transported across Caco-2 monolayer and was taken up by Caco-2 cells with very slight injury of the cell membrane up to 100 μM PC. Lactate dehydrogenase release and cell viability did not differ significantly between the treatment and control, emphasizing that injury was minimal. Our results suggest that DHA- and EPA-enriched PC enhance the permeability, transport and uptake of PC SUV across monolayers of Caco-2 cells. (Mol Cell Biochem xxx: 1–9, 2005)