Oral administration of milk-derived phospholipids inhibits penetration of cutaneous nerve fibres into epidermis in a mouse model of acute dry skin.

The density of intraepidermal nerve fibres has been shown to be higher in itchy dry skin than in healthy skin, suggesting that epidermal hyperinnervation is at least partly involved in peripheral itch sensitization. We investigated whether oral administration of milk-derived phospholipids (MPLs) would inhibit epidermal hyperinnervation in a mouse model of dry skin. We found that the number of intraepidermal nerve fibres was significantly lower in the MPL group than in the control group. Expression of nerve growth factor (NGF) levels in the epidermis was significantly decreased by oral administration of MPLs, whereas expression of semaphorin (Sema)3A, a nerve repulsion factor, was increased in the MPL group. These results suggest that dietary MPLs attenuate the penetration of nerve fibres into the epidermis by reducing epidermal NGF levels and increasing Sema3A level. Thus, dietary MPLs may have beneficial effects in the prevention and/or alleviation of dry skin-induced itch by reducing intraepidermal nerve fibre density.

Neurotropin inhibits the increase in intraepidermal nerve density in the acetone-treated dry-skin mouse model.

Epidermal hyperinnervation is considered one cause of sensitization to itch, and is thought to regulated by keratinocyte-derived axonal guidance molecules, including nerve growth factor (NGF) and semaphorin (Sema)3A. Neurotropin (NTP) shows antipruritic effects in allergic disease and is also used for pain relief. Using cultured rat dorsal root ganglion neurones, we previously found that NTP inhibited NGF-induced neurite outgrowth. However, no such inhibitory effect has been shown in vivo. We therefore assessed the effects of intraperitoneal administration of NTP on nerve density and expression of NGF and Sema3A mRNAs in the epidermis of acetone-treated mice showing epidermal hyperinnervation. We found that NTP significantly reduced intraepidermal nerve growth in these acetone-treated mice. NTP significantly upregulated epidermal Sema3A mRNA, but had no effect on expression of epidermal NGF mRNA. These findings indicate that NTP may reduce intraepidermal nerve density by inducing expression of Sema3A in the epidermis.

Functional analysis of thermo-sensitive TRPV1 in an aquatic vertebrate, masu salmon (Oncorhynchus masou ishikawae).

Transient receptor potential vanilloid 1 (TRPV1) is mainly expressed in nociceptive primary sensory neurons and acts as a sensor for heat and capsaicin. The functional properties of TRPV1 have been reported to vary among species and, in some cases, the species difference in its thermal sensitivity is likely to be associated with thermal habitat conditions. To clarify the functional properties and physiological roles of TRPV1 in aquatic vertebrates, we examined the temperature and chemical sensitivities of TRPV1 in masu salmon (Oncorhynchus masou ishikawae, Om) belonging to a family of salmonids that generally prefer cool environments. First, behavioral experiments were conducted using a video tracking system. Application of capsaicin, a TRPV1 agonist, induced locomotor activities in juvenile Om. Increasing the ambient temperature also elicited locomotor activity potentiated by capsaicin. RT-PCR revealed TRPV1 expression in gills as well as spinal cord. Next, electrophysiological analyses of OmTRPV1 were performed using a two-electrode voltage-clamp technique with a Xenopus oocyte expression system. Heat stimulation evoked an inward current in heterologously expressed OmTRPV1. In addition, capsaicin produced current responses in OmTRPV1-expressing oocytes, but higher concentrations were needed for its activation compared to the mammalian orthologues. These results indicate that Om senses environmental stimuli (heat and capsaicin) through the activation of TRPV1, and this channel may play important roles in avoiding environments disadvantageous for survival in aquatic vertebrates.

Neurotropin inhibits both capsaicin-induced substance P release and nerve growth factor-induced neurite outgrowth in cultured rat dorsal root ganglion neurones.

BACKGROUND: Neurotropin (NTP), a biological extract from rabbit skin inoculated with vaccinia virus, is an effective analgesic and anti-allergic agent, and has antipruritic effects in various dermatoses including eczema, dermatitis and urticaria. In patients receiving haemodialysis who have pruritus, NTP appears to exert its antipruritic effect by lowering the plasma levels of substance P (SP), but its underlying mechanisms are not fully understood. AIM: To investigate the antipruritic mechanisms of NTP. METHODS: The effects of NTP on capsaicin-induced SP release from neonatal rat dorsal root ganglion (DRG) neurones were assessed by measuring SP concentrations in culture media by a competitive ELISA. The effects of NTP on nerve growth factor (NGF)-induced neurite outgrowth were assessed by measuring the length of the longest process of cultured DRG neurones. The neuronal cytotoxicity of NTP was determined using a methylthiazole tetrazolium cytotoxicity assay. RESULTS: NTP dose-dependently inhibited capsaicin-induced release of SP from cultured DRG neurones, whereas NTP alone had no effect on SP release. Moreover, NTP dose-dependently inhibited NGF-induced neurite outgrowth in cultured DRG neurones. NTP had no observable cytotoxicity. CONCLUSIONS: These results suggest that NTP exerts its antipruritic effects by inhibiting both SP release and neurite outgrowth of cutaneous sensory nerves.

Significance of hair-dye base-induced sensory irritation.

Oxidation hair-dyes, which are the principal hair-dyes, sometimes induce painful sensory irritation of the scalp caused by the combination of highly reactive substances, such as hydrogen peroxide and alkali agents. Although many cases of severe facial and scalp dermatitis have been reported following the use of hair-dyes, sensory irritation caused by contact of the hair-dye with the skin has not been reported clearly. In this study, we used a self-assessment questionnaire to measure the sensory irritation in various regions of the body caused by two model hair-dye bases that contained different amounts of alkali agents without dyes. Moreover, the occipital region was found as an alternative region of the scalp to test for sensory irritation of the hair-dye bases. We used this region to evaluate the relationship of sensitivity with skin properties, such as trans-epidermal water loss (TEWL), stratum corneum water content, sebum amount, surface temperature, current perception threshold (CPT), catalase activities in tape-stripped skin and sensory irritation score with the model hair-dye bases. The hair-dye sensitive group showed higher TEWL, a lower sebum amount, a lower surface temperature and higher catalase activity than the insensitive group, and was similar to that of damaged skin. These results suggest that sensory irritation caused by hair-dye could occur easily on the damaged dry scalp, as that caused by skin cosmetics reported previously.

Reduction of extracellular sodium evokes nociceptive behaviors in the chicken via activation of TRPV1.

Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, is mainly expressed in nociceptive primary sensory neurons. Sensitivity of TRPV1 to several stimuli is known to vary among species, specifically, the avian orthologue is nearly insensitive to capsaicin. Extracellular sodium ions ([Na+]o) regulate TRPV1 activity in mammals, but their regulatory role on chicken TRPV1 (cTRPV1) is unknown. Here, we focused on the actions of capsaicin and low [Na+]o on cTRPV1 activity. In chicken dorsal root ganglion (cDRG) neurons, capsaicin elicited [Ca2+]i increases, but its effective concentration was much higher than those in mammals. Low [Na+]o evoked [Ca2+]i increases in cDRG neurons in a decreasing [Na+]o-dependent manner and the complete removal of [Na+]o (0Na) produced maximal effects. The population of 0Na-sensitive neurons was mostly overlapped with those of proton- and capsaicin-sensitive ones. Low [Na+]o synergistically potentiated the capsaicin- and proton-induced TRPV1 activation in cDRG neurons. In HEK293 cells expressing cTRPV1 (cTRPV1-HEK), capsaicin elicited [Ca2+]i increases with an EC50 of 11.8 µM, and low [Na+]o also did. Well-defined mammalian TRPV1 antagonists hardly suppressed cTRPV1 activation by low [Na+]o. 0Na evoked outwardly rectified currents in cTRPV1-HEK. Mutagenesis analyses revealed a possible interaction of [Na+]o with the proton-binding sites of cTRPV1. The administration of capsaicin and 0Na to chick eyes elicited pain-related behaviors. These results suggest that low [Na+]o is capable of activating cTRPV1 in vitro, resulting in pain in vivo. Our data demonstrate that characterization of the cTRPV1 function is important to understand activation mechanisms of TRPV1.

In vitro model for penetration of sensory nerve fibres on a Matrigel basement membrane: implications for possible application to intractable pruritus.

BACKGROUND: Epidermal hyperinnervation occurs in dermatoses with intractable pruritus, such as atopic dermatitis, suggesting that the hyperinnervation is partly responsible for abnormal itch perception. OBJECTIVES: To investigate the mechanisms of penetration of sensory nerve fibres into the basement membrane of the skin. METHODS: A rat dorsal root ganglion neurone culture system consisting of Matrigel and a Boyden chamber containing a nerve growth factor (NGF) concentration gradient was used. In some experiments, matrix metalloproteinase (MMP) blockers and semaphorin 3A (Sema3A) were added to the culture system. Matrigel-coated membranes were stained with anti-Tau antibody, and the number of nerve fibres that crossed the membrane was counted. Expression of MMPs in the cultured neurones was examined at mRNA and protein levels by quantitative reverse transcription-polymerase chain reaction and immunocytochemistry, respectively. The activity was also examined by zymography. RESULTS: Nerve fibres penetrated into Matrigel in the presence of an NGF concentration gradient, which was dose-dependently inhibited by GM6001, a broad-spectrum MMP inhibitor. Transcripts for MMP2, but not MMP9, were increased in the cultured neurones, and the penetration was dose-dependently inhibited by MMP-2 blockers. MMP-2 and its activity were partially localized on the NGF-responsive growth cones. NGF also upregulated pro-MMP-2 activation molecules in the cultured neurones. Sema3A stimulation showed the opposite effects on these NGF-dependent events. Interestingly, MMP2 expression was modulated by extracellular matrix (ECM) substrates for this enzyme. CONCLUSIONS: Membrane-associated MMP-2 contributes to penetration of nerve fibres into Matrigel through modulation by axonal guidance molecules and/or ECM. These findings provide insight for understanding the development of intractable pruritus involving epidermal nerve density.

OPC-21268, an orally effective, nonpeptide vasopressin V1 receptor antagonist.

An orally effective, nonpeptide, vasopressin V1 receptor antagonist, OPC-21268, has been identified. This compound selectively antagonized binding to the V1 subtype of the vasopressin receptor in a competitive manner. In vivo, the compound acted as a specific antagonist of arginine vasopressin (AVP)-induced vasoconstriction. After oral administration in conscious rats, the compound also antagonized pressor responses to AVP. OPC-21268 can be used to study the physiological role of AVP and may be therapeutically useful in the treatment of hypertension and congestive heart failure.

Effect of miglitol, an alpha-glucosidase inhibitor, on atherogenic outcomes in balloon-injured diabetic rats.

This study investigates the effects of miglitol, an alpha-glucosidase inhibitor, on the development of balloon-injured neointimal thickening in left common carotid artery, and the changes of glucose metabolism and inflammatory responses in Wistar fatty rats, an obese-hyperglycemic animal model, and their littermates, Wistar lean rats. Miglitol was orally administered at 40 mg/100 g of high-fat diet containing 45% kcal as fat to 12-week-old rats for 29 days, and age-matched rats without the agent were used as the respective controls. Balloon catheterization in the left common carotid artery was performed on day 15, and the artery was removed on day 29. Compared with the area ratio of the neointima/media in fatty rats without treatment, those in fatty rats with miglitol and lean rats without treatment were significantly decreased to 80%. The administration of miglitol significantly decreased the levels of plasma glucose, glycoalbumin and high-sensitivity C-reactive protein, and elevated the high-density lipoprotein-cholesterol level in fatty rats. These findings suggest that miglitol could be effective for the suppression of atherogenic outcomes in diabetic Wistar fatty rat, suggesting that the agent may have clinical benefits and contribute to prevent diabetic macroangiopathy.

The cloned capsaicin receptor integrates multiple pain-producing stimuli.

Capsaicin, the main pungent ingredient in "hot" chili peppers, elicits buming pain by activating specific (vanilloid) receptors on sensory nerve endings. The cloned vanilloid receptor (VR1) is a cation channel that is also activated by noxious heat. Here, analysis of heat-evoked single channel currents in excised membrane patches suggests that heat gates VR1 directly. We also show that protons decrease the temperature threshold for VR1 activation such that even moderately acidic conditions (pH < or = 5.9) activate VR1 at room temperature. VR1 can therefore be viewed as a molecular integrator of chemical and physical stimuli that elicit pain. Immunocytochemical analysis indicates that the receptor is located in a neurochemically heterogeneous population of small diameter primary afferent fibers. A role for VR1 in injury-induced hypersensitivity at the level of the sensory neuron is presented.

Inhibition of the transient receptor potential cation channel TRPM2 by 2-aminoethoxydiphenyl borate (2-APB).

BACKGROUND AND PURPOSE: Transient receptor potential melastatin 2 (TRPM2) is a non-selective Ca(2+)-permeable cation channel and is known to be activated by adenosine 5'-diphosphoribose (ADP-ribose) and hydrogen peroxide. TRPM2 current responses are reported to be drastically potentiated by the combination of each of these ligands with heat. Furthermore, the combination of cyclic ADP-ribose with heat also activates TRPM2. Although flufenamic acid, antifungal agents (miconazole and clotrimazole), and a phospholipase A(2) inhibitor (N-(p-amylcinnamoyl)anthranilic acid) inhibit TRPM2, their inhibition was either gradual or irreversible. EXPERIMENTAL APPROACH: To facilitate future research on TRPM2, we screened several compounds to investigate their potential to activate or inhibit the TRPM2 channels using the patch-clamp technique in HEK293 cells, transfected with human TRPM2. KEY RESULTS: 2-aminoethoxydiphenyl borate (2-APB) exhibited a rapid and reversible inhibition of TRPM2 channels that had been activated by its ADP-ribose or cADP-ribose and heat in a dose-dependent manner (IC(50) about 1 microM). 2-APB also inhibited heat-evoked insulin release from pancreatic islets, isolated from rats. CONCLUSIONS AND IMPLICATIONS: 2-APB proved to be a powerful and effective tool for studying the function of TRPM2.

Effect of tyrosine kinase inhibition by imatinib mesylate on mast cell tumors in dogs.

BACKGROUND: Imatinib mesylate is a small molecule targeted at dysregulated protein-tyrosine kinase. Mutation of c-kit exon 11, which induces constitutive phosphorylation of KIT, is one of the mechanisms for the development or progression of mast cell tumor (MCT) in dogs. The purpose of this study was to examine the therapeutic potential of imatinib mesylate in canine MCT. HYPOTHESIS: Imatinib mesylate has activity against MCT in dogs, and response to treatment can be correlated to presence of mutation within exon 11 of c-kit. ANIMALS: Twenty-one dogs with MCT with gross tumor burden and median tumor size of 7.2 cm (range, 1.0-25.3 cm) before treatment. METHODS: Tumors were analyzed for mutation of c-kit exon 11. Imatinib mesylate was administered PO to the dogs at a dose of 10 mg/kg daily for 1-9 weeks. RESULTS: Ten of 21 dogs (48%) had some beneficial response to imatinib mesylate treatment within 14 days of treatment initiation. All 5 dogs with a demonstrable c-kit mutation in exon 11 responded to the drug (1 complete remission, 4 partial remission). CONCLUSIONS AND CLINICAL IMPORTANCE: Imatinib mesylate has clinical activity against MCT in dogs. Response could not be predicted based on presence of absence of a mutation in exon 11 of c-kit.

Activation of Ca-permeable cation channels by myocarditis-associated antibody in guinea pig ventricular myocytes.

The pathogenesis of myocarditis and dilated cardiomyopathy is though to involve autoimmunological processes and myocardial calcium overload. Serum containing antiheart antibodies associated with a murine model of myocarditis increased [Ca2+]i in guinea pig ventricular myocytes only in the presence of extracellular Ca2+. The antiheart antibody-positive serum activated Ca(2+)-permeable cation channels that were insensitive to dihydropyridines and membrane stretch. The permeability sequence was Ba2+ > Ca2+ > Na+ approximately K+, and the single-channel conductance to Ba2+ was 12 pS. The channel was activated by extracellular application of the serum during on-cell recording, which suggests that a soluble intracellular messenger may be involved. The antibody-positive serum did not alter voltage-gated Ca2+ currents. We propose that excess Ca entry in myocarditis and dilated cardiomyopathy results from activation of a Ca(2+)-permeable cationic channel by the autoantibodies.

Antitumor effects of the MIG and IP-10 genes transferred with poly [D,L-2,4-diaminobutyric acid] on murine neuroblastoma.

The number of tumor-infiltrating lymphocytes is known to be related to outcomes in patients with a variety of malignancies. Interferon (IFN) gamma-inducible protein-10 (IP-10) and monokine induced by IFNgamma (MIG) have chemotactic effects on activated T lymphocytes and natural killer (NK) cells. The aim of this study was to evaluate the antitumor effects of exogenous expression of the MIG and IP-10 genes delivered to solid tumors by poly [D,L-2,4-diaminobutyric acid] (PDBA). The murine MIG and IP-10 genes were transfected into mouse neuroblastoma cells with PDBA. MIG and IP-10 levels in supernatants of transfected cells were measured by enzyme-linked immunosorbent assay. The chemotactic activities of MIG and IP-10 in the supernatants of cell cultures were measured by chemotaxis assay. Tumors were injected in vivo with PDBA/pmMIGColon, two colonsIP-10 complexes to evaluate the effects of these genes on tumor volume and survival time of mice. Transfected PDBA/pmMIGColon, two colonsIP-10 complexes produced MIG and IP-10 protein in vitro. MIG and IP-10 proteins secreted into the culture medium showed chemotactic activity. MIG and IP-10 gene therapy with the PDBA system in vivo significantly inhibited tumor growth and prolonged survival time of mice. In conclusion, PDBA-mediated MIG and IP-10 gene therapy may be useful for treatment of solid tumors.

Methyl p-hydroxybenzoate causes pain sensation through activation of TRPA1 channels.

BACKGROUND AND PURPOSE: Parabens are commonly added in pharmaceutical, cosmetic and food products because of their wide antibacterial properties, low toxicity, inertness and chemical stability, although the molecular mechanism of their antibacterial effect is not fully understood. Some agonists of the transient receptor potential (TRP) A1 channels are known to have strong antibacterial activities. Therefore, a series of experiments was conducted to find out the effects of parabens on TRP channels expressed in sensory neurons, particularly the TRPA1 channels. EXPERIMENTAL APPROACH: Effects of parabens, especially of methyl p-hydroxybenzoate (methyl paraben) on TRP channel activities were examined using Ca(2+)-imaging and patch-clamp methods. In addition, an involvement of methyl paraben in the development of pain-related behavior in mice was investigated. KEY RESULTS: Methyl paraben specifically activated TRPA1 in both HEK293 cells expressing TRPA1 and in mouse sensory neurons with an EC(50) value of 4.4 mM, an attainable concentration in methyl paraben-containing products. Methyl paraben caused pain-related behavior in mice similar to that caused by allyl isothiocyanate, which was blocked by the TRP channel blocker, ruthenium red. CONCLUSIONS AND IMPLICATIONS: Our data indicate that methyl paraben is able to activate TRPA1 channels and can cause pain sensation. As such, methyl paraben provides a useful tool for investigating TRPA1 function and development of antinociceptive agents acting on TRPA1 channels.

A multicenter study of leukocytapheresis in rheumatoid arthritis.

OBJECTIVE: To evaluate the efficacy and safety of leukocytapheresis (LCAP) in patients with rheumatoid arthritis (RA) that is refractory to disease modifying antirheumatic drugs (DMARDs), we conducted a prospective, multicenter, open-label clinical trial. METHODS: We enrolled 38 active RA patients, including 32 patients who showed an inadequate response to > or = 2 DMARDs and 6 patients with rapidly progressive RA. All patients continued drug therapy and were treated with 5 LCAP sessions conducted at 1-week intervals. The clinical response was evaluated at baseline before starting LCAP and at 4 weeks after the completion of all the LCAP sessions using the American College of Rheumatology (ACR) criteria and the 28-joint disease activity score (DAS28) of the European League Against Rheumatism (EULAR). RESULTS: Of the 35 patients who fulfilled the study's eligibility criteria, 24 (69%), 10 (29%), and 23 (66%) patients achieved 20% (ACR20), 50% (ACR50), and DAS28-C-reactive protein (CRP) EULAR improvement, respectively. The mean DAS28-CRP score of the 35 patients decreased significantly from 5.99 +/- 0.92 at baseline to 4.54 +/- 1.39 after treatment. Comparison analysis of the ACR20 responders and non-responders to LCAP revealed that 22 of 24 responders (92%) concomitantly received methotrexate, whereas significantly fewer, that is, 6 of 11 non-responders (55%) received methotrexate. Less frequent and transient mild-to-moderate adverse events, including nausea and headache, were seen in 12 of 189 LCAP sessions (6.3%). CONCLUSION: These results demonstrate the usefulness of LCAP in combination with DMARDs, particularly methotrexate, as an effective and safe treatment for refractory RA.

Nociception and TRP channels.

Pain is initiated when noxious stimuli excite the peripheral terminals of specialized primary afferent neurons called nociceptors. Many molecules are involved in conversion of the noxious stimuli to the electrical signals in the nociceptor endings. Among them, TRP channels play important roles in detecting noxious stimuli.

Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties, attenuates 5-fluorouracil-induced intestinal mucositis in mice through activation of extrinsic primary afferent neurons.

Intestinal mucositis accompanied by severe diarrhea is one of the most common side effects during cancer chemotherapy. Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties via sensory afferent neurons, is used for the treatment of upper gastrointestinal diseases. The present study investigated the effects of lafutidine on 5-fluorouracil (5-FU)-induced intestinal mucositis induced in mice. Male C57BL/6 wild-type (WT), sensory deafferented mice, and transient receptor potential vanilloid subfamily 1 knockout (TRPV1KO) mice were used. Animals were administered 5-FU once daily, while lafutidine and famotidine were administered twice daily for 6 days. Repeated administration of 5-FU caused severe intestinal mucositis, characterized by shortening of villi and destruction of crypts and was accompanied by diarrhea and body weight loss. Daily administration of lafutidine reduced the severity of intestinal mucositis, diarrhea and body weight loss in a dose-dependent manner, while famotidine had no effect on intestinal mucositis. The preventive effects of lafutidine were completely abolished in sensory deafferented and TRPV1-KO mice. Lafutidine significantly suppressed 5-FU-increased MPO activity and inflammatory cytokine expression on day 6, but not apoptosis induction in intestinal crypts on day 1. Lafutidine induced Alcian Blue and PAS-positive mucus production in the small intestine. These findings suggest that lafutidine attenuates 5-FU-induced intestinal mucositis, most likely by increasing mucus production via activation of sensory afferent neurons. Furthermore, intact TRPV1 signaling is essential for the activation of sensory afferent neurons induced by lafutidine. Therefore, lafutidine is more useful than other common antacids for the treatment of intestinal mucositis during cancer chemotherapy.

Regional pharmacokinetics of doxorubicin following hepatic arterial and portal venous administration: evaluation with hepatic venous isolation and charcoal hemoperfusion.

We evaluated the regional pharmacokinetics of doxorubicin after hepatic arterial infusion (HAI) and portal venous infusion (PVI) using a novel system for hepatic venous isolation and charcoal hemoperfusion (HVI-CHP). The HVI-CHP system was used to determine directly the doxorubicin plasma concentration in the hepatic vein and the hepatic venous flow rate, and simultaneously, to eliminate hepatic re-entry of the drug. Beagles received doxorubicin (1 mg/kg) through either the hepatic artery (HAI group, n = 6) or the portal vein (PVI group, n = 6). In both groups, hepatic venous blood was completely isolated and directed to the CHP filter. The filtered blood was returned through the left jugular vein. During HVI-CHP, the hepatic venous flow rate was monitored and plasma doxorubicin concentrations were serially measured in prefilter (= hepatic venous), postfilter, and systemic blood. The hepatic tissue uptake of doxorubicin was determined based on the blood flow rate and doxorubicin level in the hepatic vein. The hepatic extraction ratio of doxorubicin was defined as the percentage hepatic tissue uptake to the amount of drug administered. During drug infusion, similarly in either group, HVI-CHP produced a 66-87% reduction of the postfilter doxorubicin level as compared with the prefilter level. The prefilter drug level was significantly lower in HAI group than in PVI group (P < 0.01). Thus, the area under the time concentration curve for the prefilter drug level in the HAI group (6.90+/-0.96 microg min/ml) was significantly lower than that in the PVI group (18.10+/-2.90 microg min/ml, P < 0.01). Conversely, the hepatic extraction ratio in the HAI group (84.6+/-2.9%) was significantly higher than that in the PVI group (58.1+/-3.4%, P < 0.01). We conclude that in the beagle, doxorubicin is more effectively extracted by the liver when administered via the hepatic artery than when administered via the portal vein. These results indicate that HAI of doxorubicin is superior to PVI in terms of reduction of systemic drug exposure and systemic toxicity.