Stearic acid promotes lipid synthesis through CD36/Fyn/FAK/mTORC1 axis in bovine mammary epithelial cells.

Stearic acid (C18:0, SA) is a saturated long-chain fatty acid (LCFA) that has a prominent function in lactating dairy cows. It is obtained primarily from the diet and is stored in the form of triacylglycerol (TAG) molecules. The transmembrane glycoprotein cluster of differentiation 36 (CD36) is also known as fatty acid translocase, but whether SA promotes lipid synthesis through CD36 and FAK/mTORC1 signaling is unknown. In this study, we examined the function and mechanism of CD36-mediated SA-induced lipid synthesis in bovine mammary epithelial cells (BMECs). SA-enriched supplements enhanced lipid synthesis and the FAK/mTORC1 pathway in BMECs. SA-induced lipid synthesis, FAK/mTORC1 signaling, and the expression of lipogenic genes were impaired by anti-CD36 and the CD36-specific inhibitor SSO, whereas overexpression of CD36 effected the opposite results. Inhibition of FAK/mTORC1 by TAE226/Rapamycin attenuated SA-induced TAG synthesis, inactivated FAK/mTORC1 signaling, and downregulated the lipogenic genes PPARG, CD36, ACSL1, SCD, GPAT4, LIPIN1, and DGAT1 at the mRNA and protein levels in BMECs. By coimmunoprecipitation and yeast two-hybrid screen, CD36 interacted directly with Fyn but not Lyn, and Fyn bound directly to FAK; FAK also interacted directly with TSC2. CD36 linked FAK through Fyn, and FAK coupled mTORC1 through TSC2 to form the CD36/Fyn/FAK/mTORC1 signaling axis. Thus, stearic acid promotes lipogenesis through CD36 and Fyn/FAK/mTORC1 signaling in BMECs. Our findings provide novel insights into the underlying molecular mechanisms by which LCFA supplements promote lipid synthesis in BMECs.

Optimisation and Effect Analysis of the Blood Collection Method in Pre-Deposit Autotransfusion Patients Undergoing Thoracotomy Surgery.

Background and Purpose: To explore the feasibility of the modified blood collection method in pre-deposit autotransfusion in patients undergoing thoracotomy surgery. Methods: This double-blinded randomised controlled trial enrolled 92 patients from the cardiothoracic surgery department from February 2019 to October 2020. Results: Compared with the conventional blood collection method, the modified blood collection method avoided blood overflow from the oblique plane of the needle (χ2 = 61.986, P < 0.01) and reduced the diameter of the bruising area after 24 hours (χ2 = 24.611, P < 0.01). Furthermore, due to optimising the blood collection method, diastolic blood pressure reduced slightly before and after blood collection (t = 2.036, P < 0.05), and patients in the test group had less pain (based on the numerical rating score) (t = 5.556, P < 0.01). Meanwhile, the time required to collect 400 mL of blood was shortened (t = 17.744, p < 0.01). Conclusion: An improved blood collection method can enhance the blood donation experience, avoid blood spillage, lessen pain and reduce adverse reactions. This may be of great significance in ensuring blood quality and the safety of subsequent transfusions. Clinical Trials Registration: ClinicalTrials.gov Identifier: NCT05539846.

Dynamic analysis of physiological indices and transcriptome profiling revealing the mechanisms of the allelopathic effects of phenolic acids on Pinellia ternata.

Pinellia ternata (Thunb.) is a famous traditional Chinese medicine with high medicinal value, but its culture is strongly hindered by the continuous cropping obstacles (CCO) which are tightly associated with allelopathic effects. Deciphering the response mechanisms of P. ternata to allelochemicals is critical for overcoming the CCO. Here, we elucidate the response of P. ternata to phenolic acids treatment via physiological indices, cellular approaches, and transcriptome analysis. Phenolic acids showed a significant effect on the growth of P. ternata seedlings, similar to the phenotype of continuous cropping. Cellular analysis demonstrated that phenolic acids remarkably induced root cell death. Physiological analysis revealed that phenolic acids induced the overaccumulated of H2O2 and O 2 - in root cells. However, two exogenous antioxidants (L-ascorbic acid and ß-gentiobiose) aid in the scavenging of over-accumulated H2O2 and O 2 - by promoting the antioxidant enzyme activity such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Transcriptome analysis demonstrated that differentially expressed genes (DEGs) related to the cell wall degeneration and reactive oxygen species (ROS) metabolism were upregulated by phenolic acid treatment. In addition, downregulated DEGs involved in sucrose and starch metabolism and phenylpropanoid biosynthesis pathways decreased the key metabolites contents. Taken together, phenolic acids caused root cell death by inducing the overaccumulation of H2O2 and O 2 - , and L-ascorbic acid and ß-gentiobiose effectively alleviated ROS stress. The present study elucidates the underlying mechanism of the allelopathic effect of phenolic acids, offers valuable information for further understanding the mechanism of CCO, and could contribute to improving guidance for further P. ternata production.

Physicochemical Properties of the Soluble Dietary Fiber from Laminaria japonica and Its Role in the Regulation of Type 2 Diabetes Mice.

Laminaria japonica is a large marine brown alga that is annually highly productive. However, due to its underutilization, its potential value is substantially wasted. For example, a lot of Laminaria japonica cellulose remains unused during production of algin. The soluble dietary fiber (SDF) was prepared from the byproducts of Laminaria japonica, and its physicochemical properties were explored. SDF exhibits good water-holding, oil-holding, water-absorbing swelling, glucose and cholesterol absorption capacity, and inhibitory activity of α-amylase and α-glucosidase. In addition, the beneficial effects of SDF in diabetic mice include reduced body weight, lower blood glucose, and relieved insulin resistance. Finally, the intestinal flora and metabolomic products were analyzed from feces using 16S amplicon and LC-MS/MS, respectively. SDF not only significantly changed the composition and structure of intestinal flora and intestinal metabolites, but also significantly increased the abundance of beneficial bacteria Akkermansia, Odoribacter and Bacteroides, decreased the abundance of harmful bacteria Staphylococcus, and increased the content of bioactive substances in intestinal tract, such as harmine, magnolol, arachidonic acid, prostaglandin E2, urimorelin and azelaic acid. Taken together, these findings suggest that dietary intake of SDF alleviates type 2 diabetes mellitus disease, and provides an important theoretical basis for SDF to be used as a functional food.

Platelet membrane-coated nanoparticles for targeted drug delivery and local chemo-photothermal therapy of orthotopic hepatocellular carcinoma.

Specific targeted drug delivery and controllable release of drugs at tumor regions are two of the main challenges for hepatocellular carcinoma (HCC) therapy, particularly post metastasis. Herein, we present a platelet membrane-facilitated local chemo-photothermal therapy strategy, in which polypyrrole (PPy) nanoparticles act as photothermal agents and along with antitumor drug doxorubicin (DOX) are encapsulated into platelet membranes (PLT-PPy-DOX). The particles are endowed with immune evasiveness and tumor targeting abilities from platelet membranes, and are then intravenously injected into an orthotopic mouse model of HCC. As expected, the PLT-PPy-DOX nanoplatforms were abundant in the tumor tissues. Hyperthermia was generated under laser irradiation (808 nm) not only to ablate tumor cells directly but also to increase the triggered release of DOX. This combination of local chemotherapy and photothermal therapy demonstrated excellent antitumor efficiency in suppressing primary tumor growth and inhibiting tumor metastases. This localized therapy which adopts biocompatible natural cell membranes and good biodegradable organic photothermal agents may provide new insights into designing biomimetic nano-vehicles for personalized therapy of HCC.

Metabolism and Disposition of Volanesorsen, a 2'-O-(2 methoxyethyl) Antisense Oligonucleotide, Across Species.

Volanesorsen (previously known as ISIS 304801) is a 20-nucleotide partially 2'-O-(2-methoxyethyl) (2'-MOE)-modified antisense oligonucleotide (ASO) gapmer, which was recently approved in the European Union as a novel, first-in-class treatment in the reduction of triglyceride levels in patients with familial chylomicronemia syndrome. We characterized the absorption, distribution, metabolism, and excretion characteristics of volanesorsen in mice, rats, monkeys, and humans, in either radiolabeled or nonradiolabeled studies. This also included the characterization of all of the observed ASO metabolite species excreted in urine. Volanesorsen is highly bound to plasma proteins that are similar in mice, monkeys, and humans. In all species, plasma concentrations declined in a multiphasic fashion, characterized by a relatively fast initial distribution phase and then a much slower terminal elimination phase following subcutaneous bolus administration. The plasma metabolite profiles of volanesorsen are similar across species, with volanesorsen as the major component. Various shortened oligonucleotide metabolites (5-19 nucleotides long) were identified in tissues in the multiple-dose mouse and monkey studies, but fewer in the [3H]-volanesorsen rat study, likely due to a lower accumulation of metabolites following a single dose in rats. In urine, all metabolites identified in tissues were observed, consistent with both endo- and exonuclease-mediated metabolism and urinary excretion being the major elimination pathway for volanesorsen and its metabolites. SIGNIFICANCE STATEMENT: We characterized the absorption, distribution, metabolism, and excretion (ADME) of volanesorsen, a partially 2'-MOE-modified antisense oligonucleotide, from mouse to man utilizing novel extraction and quantitation techniques in samples collected from preclinical toxicology studies, a 3H rat ADME study, and a phase 1 clinical trial.

Lack of Interactions Between an Antisense Oligonucleotide with 2'-O-(2-Methoxyethyl) Modifications and Major Drug Transporters.

ISIS 141923 is a model compound of 2'-O-(2-methoxyethyl) (2'-MOE) modified antisense oligonucleotides (ASOs). The purpose of this study is to determine whether ISIS 141923 is a substrate or an inhibitor against a panel of nine major uptake or efflux drug transporters, namely breast cancer resistance protein (BCRP), P-glycoprotein (P-gp), organic anion transporter (OAT)1, OAT3, organic cation transporter (OCT)1, OCT2, organic anion transporting polypeptide 1B (OATP1B)1, OATP1B3, and bile salt export pump (BSEP), in vitro. The uptake test system for transporters in the solute carrier (SLC) family (OAT1, OAT3, OCT1, OCT2, OATP1B1, and OATP1B3) was studied in Madin-Darby canine kidney (MDCK)-II cells transfected to express the transporters of interest. BCRP was studied using carcinoma colon-2 (Caco-2) cells with endogenously expressed BCRP. P-gp transporter was studied in MDCK-multi-drug resistance 1 (MDR1) cells, while BSEP was studied using Spodoptera frugiperda 9 (Sf9) membrane vesicles containing human BSEP. The ISIS 141293 concentrations evaluated were 10 and 100 µM for the substrate and inhibition study, respectively. Cellular uptake of ISIS 141923 was analyzed using a high performance liquid chromatography-mass spectrometry method, while concentrations of known substrates (used as positive controls) of each transporters evaluated were determined by radiometric detection. At 10 µM ISIS 141923, there was no significant transporter-mediated uptake of ISIS 141923 (P > 0.05) in the SLC family, and the efflux ratios were not above 2.0 for either BCRP or P-gp. Therefore, no transporter-mediated uptake of ISIS 141923 was observed by any of the nine transporters studied. At 100 µM ISIS 141923, the % inhibition was in the range of -16.0% to 19.0% for the nine transporters evaluated. Therefore, ISIS 141923 is not considered as an inhibitor of the nine transporters studied. Overall, the results from this study suggest that it is unlikely that ISIS 141923 or similar 2'-MOE ASOs would interact with small molecule drugs either as a victim (substrate) or perpetrator (inhibitor) of major transporters in humans. The results from available clinical drug-drug interaction studies conducted with this class of compounds to date are also supportive of this conclusion.

Curcumin improves the integrity of blood-spinal cord barrier after compressive spinal cord injury in rats.

Previous studies have shown that curcumin (Cur) can produce potent neuroprotective effects against damage due to spinal cord injury (SCI). However, whether Cur can preserve the function of the blood-spinal cord barrier (BSCB) is unclear. The present study was performed to investigate the mechanism underlying BSCB permeability changes, which were induced by treatment with Cur (75, 150, and 300 mg/kg, i.p.) after compressive SCI in rats. BSCB permeability was evaluated by Evans blue leakage. Motor recovery of rats with SCI was assessed using the Basso, Beattie, and Bresnahan scoring system every day until the 21st days post-injury. The protein levels of heme oxygenase-1 (HO-1), tight junction protein, and inflammatory factors were analyzed by western blots. The expression of the inflammatory factors tumor necrosis factor-α (TNF-α) and nuclear factor-kappaB (NF-κB) mRNA was determined with reverse transcription-polymerase chain reactions. Treatment with Cur (150 and 300 mg/kg) significantly reduced Evans blue leakage into the spinal cord tissue at 24h after SCI. Cur (150 mg/kg) significantly increased HO-1 protein expression. The levels of TNF-α and NF-κB mRNA and protein greatly increased at 24h after SCI, and this increase was significantly attenuated by Cur treatment. ZO-1 and occludin expression was upregulated by Cur (150 mg/kg) treatment after SCI, and this effect was blocked by the HO-1 inhibitor zinc protoporphyrin. Long-term effects of Cur on motor recovery after SCI were observed. Our results indicated that Cur can improve motor function after SCI, which could correlate with improvements in BSCB integrity.

Gypenoside attenuates hepatic ischemia/reperfusion injury in mice via anti-oxidative and anti-apoptotic bioactivities.

Gynostemma pentaphyllum is a traditional Chinese medicine that has previously been used for the treatment of chronic inflammation, hyperlipidemia and liver disease. Gypenoside (GP), the predominant component of Gynostemma pentaphyllum, exhibits a therapeutic effect on chronic hepatic injury, fibrosis and fatty liver disease via its anti-inflammatory and anti-oxidant activity. However, the effect of GP on ischemia/reperfusion (I/R)-induced hepatic injury has, to the best of our knowledge, not previously been investigated. In the present study, a hepatic I/R-injury model was successfully established using C57BL/6 mice. In the treatment group, 50 mg/kg GP was administered orally 1 h prior to ischemia. Following hepatic I/R, the levels of hepatic lipid peroxidation and serum alanine aminotransferase increased, while the ratio of hepatic glutathione (GSH):oxidized GSH was reduced, which was effectively attenuated by pretreatment with GP. Furthermore, an increased protein expression of heme oxygenase-1 in the liver tissues of the I/R mice was attenuated by the administration of GP. In addition, the present study indicated that treatment with GP suppressed the I/R-induced increase in the pro-apoptotic protein levels of Bax and cytochrome c and the activity of caspase-3/8, as well as the I/R-induced decrease in the levels of anti-apoptotic protein Bcl-2. In conclusion, the present study indicated that GP effectively protected against I/R-induced hepatic injury via its anti-oxidative and anti-apoptotic bioactivity.

Cryoprotective effects of low-density lipoproteins, trehalose and soybean lecithin on murine spermatogonial stem cells.

Spermatogonial stem cells (SSCs) have the ability to self-renew and offer a pathway for genetic engineering of the male germ line. Cryopreservation of SSCs has potential value for the treatment of male infertility, spermatogonial transplantation, and so on. In order to investigate the cryopreservation effects of different cryoprotectants on murine SSCs, 0.2 M of low-density lipoproteins (LDL), trehalose and soybean lecithin were added to the cryoprotective medium, respectively, and the murine SSCs were frozen at -80°C or -196°C. The results indicated that the optimal recovery rates of murine SSCs in the cryoprotective medium supplemented with LDL, trehalose and soybean lecithin were 92.53, 76.35 and 75.48% at -80°C, respectively. Compared with freezing at -196°C, the optimum temperature for improvement of recovery rates of frozen murine SSCs, cryopreservation in three different cryoprotectants at -80°C, were 17.11, 6.68 and 10.44% respectively. The recovery rates of murine SSCs in the cryoprotective medium supplemented with 0.2 M LDL were significantly higher than that of other cryoprotectants (P < 0.05). Moreover, the recovery rates were demonstrated to be greater at -80°C compared with at -196°C (P < 0.05). In conclusion, 0.2 M of LDL could significantly protect murine SSCs at -80°C. In the freezing-thawing process, LDL is responsible for the cryopreservation of murine SSCs because it can form a protective film at the surface of membranes. However, more research is needed to evaluate and understand the precise role of LDL during the freezing-thawing of SSCs.

Supplement zinc as an effective treatment for spinal cord ischemia/reperfusion injury in rats.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) plays a key role in the pathophysiology process and therapy of spinal cord injury (SCI). Accordingly, zinc regulates the expression of BDNF and its receptor in the central nervous system, the mechanism of which is still unknown. The present study investigates whether supplement zinc could reduce neurological damage in a rat model, with spinal cord ischemia-reperfusion (I/R) injury and how the effect of zinc transporter 1(ZnT-1) was involved. METHODS: 100 Sprague-Dawley male rats were randomly and evenly divided into four groups. They were subjected to spinal cord ischemia by clamping the abdominal aorta for 45 min. Rats in the zinc-deficient dietary model group (ZD), zinc-adequate dietary model group (ZA), and zinc-high dietary model group (ZH) were given free access to purified diet, containing 5, 30, or 180 mg Zn/kg. Sham operation rats were subjected to laparotomy without clamping of the aorta and were fed by ZA diet (30 mg Zn/kg). Neurological function was scored by Tarlov's score. The spinal cord segments (L5) were harvested for histological examination, auto-metallographic (AMG) analysis, myeloperoxidase (MPO) activity analysis, expression of ZnT-1 and BDNF. RESULTS: The rats in the ZH group have shown the higher neurological scores, slighter histological changes and the attenuated MPO activity, compared with those in the ZD and ZA groups at the four observation time points (p<0.05). The AMG staining density in the ZH group was significantly higher than that of ZD group in 14 days later after the operation. Compared with other groups, ZH group's expression of Zn-T1 and BDNF were significantly increased, and was positively correlated with the same time points after surgery (Spearman rho=0.403, p=0.0152.) CONCLUSION: These findings suggest that zinc supplement can significantly reduce the spinal cord I/R injury in rats. The mechanism may be related with restraining the MPO activity and increasing of ZnT-1, which promoted the synthesis and release of BDNF.

The protective effect of salvianolic acid B on blood-spinal cord barrier after compression spinal cord injury in rats.

Salvianolic acid B (Sal B), a bioactive compound isolated from the Chinese medicinal herb danshen, is commonly used for the prevention and treatment of cardiovascular disease. The present study was performed to investigate the effect of Sal B on the blood-spinal cord barrier (BSCB) after spinal cord injury (SCI) in a rat model. Sal B (1, 10, and 50 mg/kg i.v.) was administered to rats immediately following SCI. The permeability of the BSCB and spinal cord tissue water content were evaluated. Additionally, the expression levels of tight junction proteins and heme oxygenase-1 (HO-1) were monitored by Western blot analysis. Enzyme-linked immunosorbent assay analysis of spinal cord tissue homogenates was performed 24 h post-SCI to evaluate the expression of inflammation-related cytokines. In addition, the motor recovery of SCI rats was assessed using the Basso, Beattie, and Bresnahan scoring system. Compared to the SCI group, rats treated with Sal B (10, 50 mg/kg) exhibited significantly reduced spinal cord tissue water content and BSCB permeability. Further, the motor function of rats was also greatly improved by Sal B administration. The expression of pro-inflammatory factors TNF-α and NF-κB was found to be greatly increased 24 h post-SCI, and this upregulation was significantly attenuated by Sal B treatment. The expression of ZO-1 and occludin was upregulated by Sal B (10 mg/kg) treatment after SCI, and this effect was blocked by the HO-1 inhibitor ZnPP. Taken together, our results clearly indicate that Sal B attenuates SCI by promoting the repair of the damaged BSCB, demonstrating that this molecule is a novel and promising therapeutic agent for human SCI.

Bioavailability enhancement of glucosamine hydrochloride by chitosan.

Glucosamine, as a dietary supplement for management of osteoarthritis, has a low and erratic oral bioavailability due to its transport-mediated absorption and presystemic loss in liver and GI tract. The present study described an effective approach to improve glucosamine intestinal absorption and hence its bioavailability using chitosan. Effects of chitosan on intestinal permeability and pharmacokinetics of glucosamine were evaluated in Caco-2 cell monolayer and rats, respectively. In addition, randomized crossover pharmacokinetic studies in beagle dogs were performed to evaluate the oral bioavailabilities of the developed glucosamine oral formulations containing chitosan (QD-Glu solution and QD-Glu tablet) in comparison to its commercial products. Caco-2 permeability studies demonstrated that chitosan could enhance the absorptive transport of glucosamine by 1.9-4.0-fold via the reversible opening of the cell tight junction. After oral administration of glucosamine solutions containing chitosan in rats, it was found that 0.5% (w/v) chitosan exhibited the highest enhancement in Cmax (2.8-fold) and AUC0-∞ (2.5-fold) of glucosamine. Further pharmacokinetic studies in beagle dogs demonstrated that QD-Glu solution and QD-Glu tablet showed much higher relative bioavailabilities of 313% and 186%, when comparing with Wellesse™ solution and Voltaflex™ tablet, respectively. In conclusion, chitosan could serve as a promising oral absorption enhancer for glucosamine.

Curcumin ameliorates the permeability of the blood-brain barrier during hypoxia by upregulating heme oxygenase-1 expression in brain microvascular endothelial cells.

Curcumin (Cur) is a major active component of the food flavor turmeric isolated from the powdered dry rhizome of Curcuma longa Linn., which has been used in traditional Chinese medicine to ameliorate intracerebral ischemic damage and reduce brain edema. However, the effects of Cur on the disruption of the blood-brain barrier (BBB) induced by brain ischemia are still unclear. The effects of Cur on the disruption of BBB and changes of tight junction (TJ) proteins induced by oxygen glucose deprivation (OGD) were studied in BBB in vitro. The transendothelial electrical resistance and the flux of horseradish peroxidase in BBB in vitro were measured. The expression and localization of the TJ proteins occludin and zonula occludens-1 (ZO-1) were evaluated by Western blots and immunofluorescence microscopy. The protein levels of heme oxygenase-1 (HO-1) were also analyzed via Western blots. Cur attenuated OGD-induced disruption of paracellular permeability and increased the expression of HO-1 protein in rat brain microvascular endothelial cells (RBMECs). After administration of OGD, the expression of occludin and ZO-1 proteins was restored by Cur, and this effect was blocked by a HO-1 inhibitor, zinc protoporphyrin (ZnPP). Cur protects RBMECs against OGD-induced disruption of TJ and barrier dysfunction via the HO-1 pathway. We propose that Cur is capable of improving the barrier function of BBB under ischemic conditions and this beneficial effect might be reversed by a HO-1 inhibitor, ZnPP.

HO-1-u-1 model for screening sublingual drug delivery--influence of pH, osmolarity and permeation enhancer.

HO-1-u-1 (Ueda-1) is a human tumor cell line established from human sublingual squamous cell carcinoma. In previous study, HO-1-u-1 cell line was grown on cell culture inserts and utilized as in vitro model for screening sublingual drug delivery. The aim of current study was to further investigate the effects of pH, osmolarity and permeation enhancer, sodium glycodeoxycholate (GDC) on the permeability of three beta-blockers with different lipophilicities. The cytotoxicity was evaluated by MTS/PES assay. The permeability studies were carried out using the cell culture model and compared with that obtained from fresh porcine sublingual mucosa. The results showed the enhancement effects caused by pH, osmolarity and GDC were highly lipophilicity-dependent and in the order atenolol>metoprolol>propranolol. The apparent permeability coefficients (P(app)) of all the three beta-blockers were significantly increased by increasing pH. However, less enhancing effects were observed by non-physiological osmolarity or the presence of GDC in permeability study using both cell culture and porcine sublingual mucosa. The present results suggested that the HO-1-u-1 cell culture model maybe a useful and effective in vitro model for evaluating the enhancement effects and mechanism in sublingual drug delivery.

Evaluation of HO-1-u-1 cell line as an in vitro model for sublingual drug delivery involving passive diffusion--Initial validation studies.

The aim of this study was to provide preliminary validation of a new sublingual mucosal cell line (HO-1-u-1) for use as in vitro sublingual drug delivery screening of compounds involving passive diffusion. HO-1-u-1 cells were seeded on cell culture inserts. The ultrastructure and integrity of cell layers, inter-passage variation and directionality of drug transport, and apparent permeability coefficient (P(app)) of eight beta-blockers (representing compounds involving passive diffusion) were determined. HO-1-u-1 cells grown on inserts formed stratified and epithelial-like structure and maintained the typical histological features of normal human sublingual epithelium. The maximal integrity of the cell layer was reached in 23 days. No significant inter-passage variation was found at the passages ranging from 2 to 11 when measured by radiolabeled transcellular and paracellular markers (testosterone and mannitol, respectively). Bidirectional transport studies confirmed the passive diffusion as the mechanism of transport for these markers. The P(app) of eight beta-blockers across HO-1-u-1 cell culture ranged from 2.89+/-0.17 to 6.37+/-0.37x10(-6)cm/s and correlated well to the P(app) obtained from porcine sublingual mucosa (r(2)=0.647 and 0.83 when excluding propranolol). The above results indicate that the HO-1-u-1 cells grown on inserts may offer as a potentially in vitro model for screening sublingual drug permeation involving passive diffusion.