Minimum Pore Diameter Research Articles

Investigation of Coronal Leakage of Root Fillings After Smear-Layer Removal with EDTA or Nd:YAG Lasing Through Capillary-Flow Porometry

This study investigates the effects of Nd:YAG laser irradiation combined with different irrigation protocols on the marginal seal of root fillings. Limited information exists regarding the effects of morphologic changes to root canal (RC) walls after Nd:YAG laser irradiation after smear-layer removal with EDTA on the sealing ability of root fillings. The 75 root-filled teeth (5 × 15 teeth) were analyzed for through-and-through leakage by using capillary flow porometry (CFP). The RC cleaning procedure determined the assignment to a group: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Nd:YAG lasing (dried RC), (3) NaOCl 2.5% + Nd:YAG lasing (dried RC), (4) SP + Nd:YAG lasing (wet RC), or (5) NaOCl 2.5% + Nd:YAG lasing (wet RC). Groups 1r to 5r consisted of the same filled teeth with resected apices up to the most apical point of the preparation length. Resection was performed after the first CFP measurement. Roots were filled with cold lateral condensation. CFP was used to assess minimum, mean flow and maximum pore diameters after 48 h, and immediately after these measurements, including root resection. Statistics were performed by using nonparametric tests (p > 0.05). An additional three roots per group were submitted to SEM of the RC wall. Through-and-through leakage was observed in all groups. Statistically significant differences were observed in maximum pore diameter: 1r > 3r, and 1r > 5r; in mean flow pore diameter: 1r > 2r, 2r < 4r (p < 0.05). Typical Nd:YAG glazing effects were observed when the smear layer was present and exposed to the laser fiber (i.e., in the groups without use of EDTA) or when the fiber tip made direct contact with a smear-layer free RC wall. The reduction in through-and-through leakage is significantly higher with the Nd:YAG laser as smear-layer modifier than when smear layer is removed with an EDTA rinsing solution.

Obstruction of Pores in Distal Protection Filters and Angiographically-Documented Flow Impairment During Carotid Artery Stenting

To determine any relationship between angiographically documented flow impairment associated with the Angioguard XP cerebral protection filter during carotid artery stenting (CAS) and the condition of the pores in the retrieved filter. To obtain baseline characteristics of the Angioguard XP, an unused filter was fully expanded and examined photographically from the cephalad end of the device to determine the structure of the pores in the filter basket. Ten pores assembled in a hexagonal pattern made up a pore group, several of which were arranged in 4 concentric rings surround a central hub that did not have any pores. For each ring of pore groups, the ring diameter, number of pore groups, and the mean minimum pore diameter were measured on a plane perpendicular to the long axis of the device. From these, the area of the ring membrane, the area of the pores, and the ratio of pore area to membrane area were calculated for each ring. Filters retrieved from 56 CAS procedures were retrospectively analyzed along with the operative records and intraprocedural angiograms performed after filter placement, predilation, stent placement, postdilation, aspiration of blood, and filter retrieval. The operators classified blood flow immediately before filter retrieval as normal, slow, or stopped. After retrieval, the filter was cut, rinsed with saline, fixed in 10% neutral buffer formalin, and macroscopically and microscopically inspected. The number of the open pores without any obstruction was counted for each ring. Retrieved filters from flow-impaired cases showed a significantly lower percentage of open pores in comparison to normal-flow cases (p<0.05). In some normal-flow cases, however, the obstruction rates were higher than mean obstruction rates of the slow-flow cases. In normal-flow cases, <5% of pores from the center to the second ring of the filter were open; this constituted more than two thirds of the entire filter diameter. The flow state on DSA was related to, but did not completely depend on, filter patency. The low patency rate of the filter in normal-flow cases suggested that flow impairment was occurring but could not be detected by the qualitative evaluation of flow on angiography.

Controlling macropore formation in patterned n-type silicon: Existence of a pitch-dependent etching current density lower bound

Experimental results on back-side illumination electrochemical etching of patterned (hole square-lattices with pitch p from 2 to 50 μm) n-type silicon substrates in HF-based electrolytes are reported. Experiments reveal the existence of a threshold current density J pitch , which is strictly correlated to the pattern pitch, above which pore formation can be finely controlled beyond commonly accepted state-of-the-art rules. For instance, using the same silicon substrate, pore array with density D spanning over two orders of magnitude (from 0.0025 μm − 2 up to of 0.25 μm − 2 ) can be etched above a minimum porosity P min , and, in turn, a minimum pore diameter d min , which depends on the pattern pitch . Etching current densities below such a critical value give rise to uncontrolled pore growth. The occurrence of the threshold current density J pitch is interpreted in terms of current burst model.

Further analysis of counterion permeation through anion-selective glycine receptor channels

The functional role of ion channels, which allow counterion permeation, depends critically on their relative anion-cation relative selectivity. From whole-cell patch clamp reversal potential measurements under dilution potential conditions, we have already shown that anion-cation permeabilities of anion-selective wild-type (WT) and mutant (with larger pore diameter) glycine receptor (GlyR) channels in the presence of Li+, Na+ and Cs+ counterions, were inversely correlated with the equivalent hydration diameter of the counterion, with chloride-cation permeability increasing as counterion equivalent hydration diameter increased with respect to the channel minimum pore diameter. Corrected for liquid junction potentials (LJPs; using ion activities), the previous chloride-cation permeabilities for the alkali cations were 23.4 (Li+), 10.9 (Na+) and 5.0 (Cs+) for the smaller WT channel. Further analysis to incorporate an initial offset potential correction, to fully allow for slight differences between internal cell composition and external control salt solution, changed the above permeability ratios to 30.6 (Li+), 11.8 (Na+) and 5.0 (Cs+), adding enhanced support for the inverse correlation between anion-to-counterion permeability ratio and equivalent hydrated counterion diameter relative to channel pore diameter (erroneously ignoring LJPs reduces each permeability ratio to about 4). Also, new direct measurements of LJPs (for NaCl and LiCl salt dilutions) using a 3M KCl-agar reference salt bridge (with freshly-cut end for each solution composition change) have shown excellent agreement with calculated LJPs (using ion activities), validating calculated LJP values. We continue to suggest that counterion cations permeate with chloride ions as neutral pairs.

Comparative pollen morphology of Turkish species of Petrorhagia (Caryophyllaceae) and its systematic implications

Pollen morphology of 10 taxa from Turkey, four of them endemic, belonging to the genus Petrorhagia (Caryophyllaceae), P. alpina subsp. alpina, P. alpina subsp. olympica, P. cretica, P. dubia, P. hispidula, P. lycica, P. pamphylica, P. peroninii, P. prolifera and P. saxifraga, has been investigated using light (LM) and scanning electron (SEM) microscopy. Pollen morphology differences among these taxa have been determined. The pollen type of investigated taxa is polyporate (12–22-porate), sphaeroidal, the exine exhibits a tectate structure and a microechinate ornamentation. Petrorhagia alpina subsp. alpina has the smallest pollen grain diameter (18.57 μm) and P. dubia the largest one (37.80 μm). The number of pores ranges from 12 (in P. dubia and P. saxifraga) to 22 (in P. alpina subsp. alpina and P. alpina subsp. olympica and P. hispidula) with a minimum pore diameter of 2.37 μm in P. alpina subsp. alpina and a maximum pore diameter of 4.23 μm in P. peroninii. The exine thickness ranges from 1.73 μm in P. saxifraga to 3.78 μm in P. pamphylica. In this study, the systematic implications are discussed in the light of palynological results.

Long‐term sealing ability of Resilon apical root‐end fillings

To evaluate ex vivo the long-term sealing ability of the SE Resilon Epiphany system as an apical root-end filling material. A total of 60 standardized horizontal bovine root sections were divided into three groups filled with either gutta-percha with AH 26, tooth-coloured mineral trioxide aggregate (MTA) or Resilon pellets with Epiphany SE, and submitted to capillary flow porometry at 48 h, 1 and 6 months to assess the minimum, mean flow and maximum pore diameters. Results of the different materials and results by material and time were analysed statistically using nonparametric tests; the level of significance was set at 0.05. Resilon had smaller pore diameters than gutta-percha and MTA at 48 h and smaller mean flow and maximum pore diameters than gutta-percha and MTA at 1 month. At 6 months Resilon had larger minimum pore diameters than gutta-percha. Although not always statistically significant, the minimum, mean flow and maximum pore diameters of gutta-percha and MTA diminished with time. This was not the case for Resilon, where the same parameters increased. All materials leaked at all times. Resilon performed better than gutta-percha and MTA in the short-term, but the seal of MTA and gutta-percha improved over time whereas the seal of Resilon deteriorated. It is critical to evaluate the performance of materials in the long-term contrary to most studies which are short-term.

Pore-Size Dependence of the Acidic Property of Mesoporous Silica FSM-16

The pore-size dependence of the acidic properties of mesoporous silica FSM-16 in the range from 1.8 to 3.8 nm was investigated with the catalysis of 2-butanol dehydration and using FTIR spectra of adsorbed pyridine. The activity was the highest for FSM-16 with a minimum pore diameter, and decreased with increasing pore size. Differences in the acid amounts of siliceous FSM-16 and the strength dependent on the pore diameter were not confirmed by FTIR characterization using pyridine as a probe molecule.

Analysis of seepage characters in fractal porous media

In this paper, the plane-radial and plane-parallel flows for Newtonian fluid in fractal porous media are analyzed. Based on the assumption that the porous medium consists of a bundle/set of tortuous streamlines/capillaries and on the fractal characteristics of pore size distribution in porous media, the expressions for porosity, flow rate, velocity and permeability for both radial and parallel flows are developed. The obtained expressions are the functions of tortuosity, fractal dimension, maximum and minimum pore diameters, and there are no empirical constant and every parameter has clear physical meaning in the expressions. The pressure distribution equations for plane-radial and plane-parallel flows in fractal porous media are also derived. The pressure and velocity distributions in plane-radial reservoirs are calculated and discussed.

Formation of dense silicon carbide by liquid silicon infiltration of carbon with engineered structure

Fully dense and net-shaped silicon carbide monoliths were produced by liquid silicon infiltration of carbon preforms with engineered bulk density, median pore diameter, and chemical reactivity derived from carbonization of crystalline cellulose and phenolic resin blends. The ideal carbon bulk density and minimum median pore diameter for successful formation of fully dense silicon carbide by liquid silicon infiltration are 0.964 g cm−3and approximately 1 μm. By blending crystalline cellulose and phenolic resin in various mass ratios as carbon precursors, we were able to adjust the bulk density, median pore diameter, and overall chemical reactivity of the carbon preforms produced. The liquid silicon infiltration reactions were performed in a graphite element furnace at temperatures between 1414 and 1900 °C and under argon pressures of 1550, 760, and 0.5 Torr for periods of 10, 15, 30, 60, 120, and 300 min. Examination of the results indicated that the ideal carbon preform was produced from the crystalline cellulose and phenolic resin blend of 6:4 mass ratio. This carbon preform has a bulk density of 0.7910 g cm−3, an actual density of 2.1911 g cm−3, median pore diameter of 1.45 μm, and specific surface area of 644.75 m2g−1. The ideal liquid silicon infiltration reaction conditions were identified as 1800 °C, 0.5 Torr, and 120 min. The optimum reaction product has a bulk density of 2.9566 g cm−3, greater than 91% of that of pure β–SiC, with a β–SiC volume fraction of approximately 82.5%.

Fabrication of Cylindrical Nanopores and Nanopore Arrays in Silicon-On-Insulator Substrates

Electron-beam lithography and reactive ion etching were used to process silicon-on-insulator substrates for the fabrication of single cylindrical high-aspect-ratio solid-state nanopores and high-packing-density nanopore arrays. Minimum pore diameters of 40 nm were readily achieved with a high yield. The electrolyte concentration dependence of ion transport through single nanopores was measured for pores with diameters ranging from 40 to 140 nm. Measured single-nanopore conductances in high salt concentrations were compared to a simple model using a cylindrical resistance path and bulk solution conductivity. Electrochemical impedance spectroscopy was used to study the ac response of the device.

A Novel Technique For Determining Microscopic Pore Size Distribution of Heterogeneous Reservoir Rocks

Fluid flow in porous media is affected by petrophysical properties and their distribution. Standard techniques of core analysis provide an average of varying petrophysical properties and pore size distribution (PSD) of porous rocks. However, these techniques have severe assumptions that may negatively influence the results obtained. The major objectives of this study are to develop a new technique capable of providing the microscopic PSD of heterogeneous reservoir rocks and to apply this technique to interpret the formation damage problem due to sulfur deposition. The current methods of calculating the pore size distribution were reviewed and evaluated. To achieve the objectives of this study, 10 reservoir rock samples extracted from an actual oil reservoir were photographed using a scanning electron microscope (SEM) and analyzed using computer software to provide the PSD. In order to investigate the application of the proposed technique, actual sulfuric crude oil was flooded through an actual core sample and the in-situ deposited sulfur along the damaged core sample was calculated, plugged, and the opening pores of the core were quantified. The results showed that a new technique capable of explaining and providing the required information about pore size distribution and its applications on a microscopic scale was developed. In addition, the influences of fluid flow characteristics of elemental sulfur through reservoir rock were presented. The newly proposed technique provided valuable data such as PSD, minimum and maximum pore diameters, plugged and nonplugged areas, and deposited amounts of damaging elements. The judicious applications of the attained results represent an impact in studying and/or evaluation of formation damage, designing the microbial enhanced oil recovery process, and development and validation of many oil reservoir simulation models.

Regulation of CRAC Channel Activity by Recruitment of Silent Channels to a High Open-probability Gating Mode

CRAC (calcium release-activated Ca2+) channels attain an extremely high selectivity for Ca2+ from the blockade of monovalent cation permeation by Ca2+ within the pore. In this study we have exploited the blockade by Ca2+ to examine the size of the CRAC channel pore, its unitary conductance for monovalent cations, and channel gating properties. The permeation of a series of methylammonium compounds under divalent cation-free conditions indicates a minimum pore diameter of 3.9 Å. Extracellular Ca2+ blocks monovalent flux in a manner consistent with a single intrapore site having an effective Ki of 20 μM at −110 mV. Block increases with hyperpolarization, but declines below −100 mV, most likely due to permeation of Ca2+. Analysis of monovalent current noise induced by increasing levels of block by extracellular Ca2+ indicates an open probability (Po) of ∼0.8. By extrapolating the variance/mean current ratio to the condition of full blockade (Po = 0), we estimate a unitary conductance of ∼0.7 pS for Na+, or three to fourfold higher than previous estimates. Removal of extracellular Ca2+ causes the monovalent current to decline over tens of seconds, a process termed depotentiation. The declining current appears to result from a reduction in the number of active channels without a change in their high open probability. Similarly, low concentrations of 2-APB that enhance ICRAC increase the number of active channels while open probability remains constant. We conclude that the slow regulation of whole-cell CRAC current by store depletion, extracellular Ca2+, and 2-APB involves the stepwise recruitment of silent channels to a high open-probability gating mode.

Thermally bonded nonwoven filters composed of bicomponent polypropylene/polyester fiber. I. Statistical approach for minimizing the pore size

AbstractA statistical approach involving the uniform design of experiments and regression analysis is used to investigate the effects of thermal bonding process parameters, dwell time, thermal bonding temperature, and hot air velocity, on the pore size of three‐dimensional (3D) nonwoven filters. These filters are produced from polypropylene (PP)/polyester (PET) (sheath/core) bicomponent staple fibers. The pore structures of the filter samples were examined using the capillary flow porometer. Results reveal that the statistical approach is effective in identifying the effects of the investigated process parameters on both the bubble point pore diameter and the mean flow pore diameter for the thermally bonded nonwoven filter samples. Under the optimized processing parameters for achieving the minimized pore size, the predicted minimum bubble point pore diameter is 111.12 μm and the predicted minimum mean flow pore diameter is 63.4 μm for the filter sample with the area density of 60 g/m2. They are in good agreement with the experimental values of 111.71 and 60.91 μm, respectively. Microstructure features observed using scanning electron microscope indicate that the effects of the investigated process parameters on the pore size are closely related to the thermal energy delivered to the fibers and the pressure drop acting on the fabrics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2689–2699, 2006

Long‐term assessment of the seal provided by root‐end filling materials in large cavities through capillary flow porometry

To evaluate the long-term sealing ability of a variety of materials when used as root-end fillings. A total of 140 standardized horizontal bovine root sections (external diameter: 7 mm, height: 3 mm; internal diameter: 2.5 mm) were divided into seven groups, filled with either gutta-percha with AH26, Ketac Fil, Fuji IX, Tooth-Colored MTA, IRM, Ketac Fil with conditioner or Fuji IX with conditioner and submitted to capillary flow porometry at 1 and 6 months to assess minimum, mean flow and maximum pore diameters. Results of the different materials and results by material were analysed statistically using non-parametric tests; the level of significance was set at 0.05. There were no significant differences between the minimum pore diameters associated with the materials at each time. At 1 month the mean flow pore diameters of Ketac Fil were significantly larger than those of gutta-percha, Ketac Fil with conditioner, Fuji IX with conditioner and IRM. There were significant differences between the maximum pore diameters at 1 month (all>IRM; Fuji IX>gutta-percha, Ketac Fil with conditioner, Fuji IX with conditioner) and 6 months (Fuji IX>gutta-percha, IRM; Ketac Fil>gutta-percha, IRM). There were significant differences in the minimum pore diameters between the different points in time for each material except IRM, in the mean flow pore diameters for each material and in the maximum pore diameters for each material except MTA. All materials were associated with capillary flow. IRM root-end fillings had through pores that were smaller than those associated with other materials. Conventionally setting glass-ionomer cements had the largest pores, although dentine conditioning improved their performance. The seal of all materials improved after 6 months.

Capillary Flow Porometry to Assess the Seal Provided by Root-End Filling Materials in a Standardized and Reproducible Way

This in vitro study evaluated the root-end sealing ability of gutta-percha + AH26 (GP), Ketac-Fil, Fuji IX (FIX), tooth-colored MTA (MTA), IRM, Ketac-Fil + conditioner (Ketac-FilC), and Fuji IX + conditioner (FIXC). A total of 140 standardized bovine root sections were divided into seven groups, filled with the mentioned root-end filling materials, and, at 48 h, submitted to capillary flow porometry to assess minimum, mean flow and maximum pore diameters. Results were statistically analyzed using nonparametric Kruskal-Wallis and Dunn tests. Level of significance was set at 0.05. Using the Kruskal-Wallis tests we found that there was no significant difference between the minimum pore diameters of the different materials, but significant differences between the mean flow (p < 0.001) and maximum (p < 0.001) pore diameters could be demonstrated. For the mean flow pore diameters, there was a significant difference between FIX and all other materials, between Ketac-Fil and IRM and between Ketac-FilC and IRM. Concerning maximum pore diameters, there was a significant difference between FIX and all other materials, between Ketac-Fil and MTA, GP and IRM, FIXC and IRM, and Ketac-FilC and IRM. The data showed that each sample had leaked. Glass ionomer cements leaked more than other materials, although dentin conditioning diminished the maximum through pore diameters. This maximum pore diameter, which corresponds to the largest leak in the sample, together with the size of bacteria and their metabolites, will be indicative of the eventual leakage along the root-end filling materials.

Optimising bioactive glass scaffolds for bone tissue engineering

A 3D scaffold has been developed that has the potential to fulfil the criteria for an ideal scaffold for bone tissue engineering. Sol–gel derived bioactive glasses of the 70S30C (70 mol% SiO 2, 30 mol% CaO) composition have been foamed to produce 3D bioactive scaffolds with hierarchical interconnected pore morphologies similar to trabecular bone. The scaffolds consist of a hierarchical pore network with macropores in excess of 500 μm connected by pore windows with diameters in excess of 100 μm, which is thought to be the minimum pore diameter required for tissue ingrowth and vasularisation in the human body. The scaffolds also have textural porosity in the mesopore range (10–20 nm). The scaffolds were sintered at 600, 700, 800 and 1000 °C. As sintering temperature was increased to 800 °C the compressive strength increased from 0.34 to 2.26 MPa due to a thickening of the pore walls and a reduction in the textural porosity. The compressive strength is in the range of that of trabecular bone (2–12 MPa). Importantly, the modal interconnected pore diameter (98 μm) was still suitable for tissue engineering applications and bioactivity is maintained. Bioactive glass foam scaffolds sintered at 800 °C for 2 h fulfill the criteria for an ideal scaffold for tissue engineering applications.

Organic Cation Permeation through the Channel Formed by Polycystin-2

Polycystin-2 (PC2), a member of the transient receptor potential family of ion channels (TRPP2), forms a calcium-permeable cation channel. Mutations in PC2 lead to polycystic kidney disease. From the primary sequence and by analogy with other channels in this family, PC2 is modeled to have six transmembrane domains. However, most of the structural features of PC2, such as how large the channel is and how many subunits make up the pore of the channel, are unknown. In this study, we estimated the pore size of PC2 from the permeation properties of the channel. Organic cations of increasing size were used as current carriers through the PC2 channel after PC2 was incorporated into lipid bilayers. We found that dimethylamine, triethylamine, tetraethylammonium, tetrabutylammonium, tetrapropylammonium, and tetrapentylammonium were permeable through the PC2 channel. The slope conductance of the PC2 channel decreased as the ionic diameter of the organic cation increased. For each organic cation tested, the currents were inhibited by gadolinium and anti-PC2 antibody. Using the dimensions of the largest permeant cation, the minimum pore diameter of the PC2 channel was estimated to be at least 11 A. The large pore size suggests that the primary state of this channel found in vivo is closed to avoid rundown of cation gradients across the plasma membrane and excessive calcium leak from endoplasmic reticulum stores.

Zirconia–zircon composite microfiltration membranes based on porous alumina supports

Supported zirconia–zircon composite microfiltration layers produced by the dip-coating procedure are introduced for the first time. These can be produced using commercial grade monoclinic-zirconia powders having high silica content. Such membranes have the advantage of enhanced sintering due to a liquid-phase mechanism. These were prepared through dip-coating α-alumina supports with slips of zirconia powder stabilized with ‘aluminon’ and further sintering (1050–1200 °C). Optimum dispersant concentration and pH had been found based on sedimentation tests and UV–vis spectroscopy method. The effect of slip concentration, sintering temperature and number of coatings on the membrane characteristics has been studied. There exists a maximum sintering temperature of 1150 °C for the creation of minimum pore diameters lower than 0.2 μm with a reasonable surface microhardness of Hardness Vickers at 50 g force pyramidal load (ca. 110 HV50) and no observable crack. This work includes a comparative study with membrane layers produced with an analogous preparatory method using high purity monoclinic zirconia with a similar particle size distribution.

Multiscale Porosity from Thermoreversible Poly(vinylidene fluoride) Gels in Diethyl Azelate

AbstractPoly(vinylidene fluoride) (PVF2) produces thermoreversible gels in a series of diesters. The polymer‐solvent complexation occurred for intermittent number of carbon atoms n ⩾ 2 and the enthalpy of complexation increased with increasing n. The gels were dried by replacing the diesters with low boiling solvent like cyclohexane (bp. 80 °C) and methylcyclohexane (bp. 99 °C). The porosity of the dried gels was measured using Poremaster‐60. For PVF2‐DEAZ gel meso and macro porosity have been observed. The former pore dimensions have been attributed for polymer‐solvent complexation while the macroporosity has been attributed for caging of solvent between the PVF2 fibrils The porosity measured from nitrogen adsorption isotherms using BJH method indicate presence of minimum pore diameter of 3.8 nm for the 10% dried gel of PVF2.

Functional Characterization of a P2X Receptor from Schistosoma mansoni

The cloning and characterization of a P2X receptor (schP2X) from the parasitic blood fluke Schistosoma mansoni provides the first example of a non-vertebrate ATP-gated ion channel. A number of functionally important amino acid residues conserved throughout vertebrate P2X receptors, including 10 extracellular cysteines, aromatic and positively charged residues involved in ATP recognition, and a consensus protein kinase C site in the amino-terminal tail, are also present in schP2X. Overall, the amino acid sequence identity of schP2X with human P2X(1-7) receptors ranges from 25.8 to 36.6%. ATP evoked concentration-dependent currents at schP2X channels expressed in Xenopus oocytes with an EC(50) of 22.1 microM. 2',3'-O-(4-Benzoylbenzoyl)adenosine 5'-triphosphate (Bz-ATP) was a partial agonist (maximum response 75.4 +/- 4.4% that of ATP) with a higher potency (EC(50) of 3.6 microM) than ATP. Suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid blocked schP2X responses to 100 microm ATP with IC(50) values of 9.6 and 0.5 microM, respectively. Ivermectin (10 microM) potentiated currents to both ATP and Bz-ATP by approximately 60% with a minimal effect on potency (EC(50) of 18.2 and 1.6 microM, respectively). The relative permeability of schP2X expressed in HEK293 cells to various cations was determined under bi-ionic conditions. schP2X has a relatively high calcium permeability (P(Ca)/P(Na) = 3.80 +/- 0.29) and an estimated minimum pore diameter similar to that of vertebrate P2X receptors. SchP2X provides a useful comparative model for the better understanding of human P2X receptor function and may also provide an alternative drug target for treatment of schistosomiasis.