Blue LED light exposure develops intracellular reactive oxygen species, lipid peroxidation, and subsequent cellular injuries in cultured bovine retinal pigment epithelial cells

The effects of blue light emitter diode (LED) light exposure on retinal pigment epithelial cells (RPE cells) were examined to detect cellular damage or change and to clarify its mechanisms. The RPE cells were cultured and exposed by blue (470 nm) LED at 4.8 mW/cm(2). The cellular viability was determined by XTT assay and cellular injury was determined by the lactate dehydrogenase activity in medium. Intracellular reactive oxygen species (ROS) generation was determined by confocal laser microscope image analysis using dihydrorhodamine 123 and lipid peroxidation was determined by 4-hydroxy-2-nonenal protein-adducts immunofluorescent staining (HNE). At 24 h after 50 J/cm(2) exposures, cellular viability was significantly decreased to 74% and cellular injury was significantly increased to 365% of control. Immediately after the light exposure, ROS generation was significantly increased to 154%, 177%, and 395% of control and HNE intensity was increased to 211%, 359%, and 746% of control by 1, 10, and 50 J/cm(2), respectively. These results suggest, at least in part, that oxidative stress is an early step leading to cellular damage by blue LED exposure and cellular oxidative damage would be caused by the blue light exposure at even lower dose (1, 10 J/cm(2)).

Regulation of μ-opioid type 1 receptors by microRNA134 in dorsal root ganglion neurons following peripheral inflammation

BACKGROUND

MOR1 is the main transcript of μ-opioid receptor (MOR) gene, which represents a mandatory molecule for the analgesic effects of opioids and plays an important role in the pathology of inflammatory pain. MicroRNAs (miR) are non-coding molecules that primarily modulate gene expression at the post-transcriptional level in various pathophysiological conditions. Based on in silico analysis, an exact match to the seed sequence of miR-134 was found in 3'-untranslated region of MOR1. Given the important roles of MOR1 in pain modulation, the purpose of this study is to investigate whether miR-134 can regulate the MOR1 following allodynia.

METHODS

Using Freund's adjuvant (CFA)-induced chronic inflammatory pain model, we investigated the expression profiles of miR-134 and MOR1 in rat dorsal root ganglia (DRG) using quantitative real-time polymerase chain reaction, in situ hybridization and immunohistochemistry, respectively. The relationship of miR-134 and MOR1 expressions was analysed by linear regression. Luciferase assay was used to examine whether MOR1 was the target of miR-134.

RESULTS

Our results showed that miR-134 expression level was inversely related to MOR1 expression. Down-regulation of miR-134 and up-regulation of MOR1 in the same tissues after inflammatory pain were observed. Functional experiments showed that MOR1 expression in SH-SY5Y cells was up-regulated after inhibition of miR-134, indicating that MOR1 was a target of miR-134.

CONCLUSIONS

Our present data suggested a model that miR-134 participated in CFA-induced inflammatory pain by balancing the expression of MOR1 in DRGs, which implied that miR-134 may be a potential therapeutic target for the treatment of neuropathic pain including inflammation.

Suppression of matrix metalloproteinase production from nasal fibroblasts by macrolide antibioticsin vitro

It is well known that low-dose and long-term administration of macrolide antibiotics favourably modify the clinical status of chronic airway inflammatory diseases. However, the therapeutic mode of action of macrolide antibiotics is not well understood. The present study aimed to examine the influence of macrolide antibiotics, roxithromycin (RXM) and josamycin (JM) on matrix metalloproteinase (MMP) production from nasal polyp fibroblasts (NPF) in vitro. NPF, at a concentration of 2.5 x 10(5) cells x mL(-1), were stimulated with tumour necrosis factor (TNF)-alpha in the presence of various concentrations of RXM or JM for 24 h. MMP-2 and -9 levels in culture supernatants were analysed by ELISA, and MMP mRNA expression was examined by RT-PCR. The influence of RXM on nuclear factor (NF)-kappaB and activator protein (AP)-1 activation was also examined. Addition of RXM (but not JM) at 5.0 and 7.5 microg x mL(-1) significantly suppressed the production of MMP-2 and -9 from NPF induced by TNF-alpha stimulation. RXM also suppressed MMP mRNA expression through the inhibition of NF-kappaB and AP-1 activation. The present results suggest that the suppressive activity of roxithromycin on MMP-2 and -9 production is, in part, responsible for the therapeutic action of macrolides on chronic airway inflammatory diseases.

Influence of a macrolide antibiotic, roxithromycin, on mast cell growth and activation in vitro

BACKGROUND

Long-term administration of macrolide antibiotics is recognized to be able to favorably modify the clinical condition of inflammatory diseases, such as diffuse panbronchiolitis and cystic fibrosis. However, the precise mechanisms by which macrolide antibiotics could improve clinical conditions of the patients are not well understood.

AIM

The present study was designed to examine the influence of macrolide antibiotics on effector cell functions responsible for inflammation through the choice of roxithromycin (RXM) and mast cell.

METHODS

Mast cells were induced by long-term culture of splenocytes from BALB/c mice. RXM was added to the cultures at seeding and then every 4-5 days, when the culture medium was replaced with a fresh one. The influence of RXM on mast cell growth was evaluated by counting the number of cells grown on the 16th day. We also examined the influence of RXM on mast cell activation by examining histamine release and inflammatory cytokine secretion.

RESULTS AND CONCLUSION

RXM could not inhibit mast cell growth, even when splenocytes were exposed to 100 microg/ml of RXM throughout the entire culture periods. RXM also could not suppress histamine release from cultured mast cells in response to non-immunological and immunological stimulations. However, RXM could suppress inflammatory cytokine, interleukin-1beta, interleukin-6, granulocyte macrophage-colony stimulating factor and tumor necrosis factor-alpha, secretions induced by concanavalin A stimulation at a concentration of as little as 0.5 microg/ml. These results may suggest that RXM modulated the ability of mast cells to secrete inflammatory cytokines and results in improvement of clinical condition of chronic inflammatory diseases.

Analgesic effect of endomorphin-1

AIM

To study the analgesic effect of endomorphin-1 (EM-1).

METHODS

The experiment was performed in rats and mice to study the analgesic effect of intraperitoneal (ip) injection of EM-1 with tail stimulation-vocalization test, writhing test, adjuvant arthritis, and neuropathic pain model and to compare it with the analgesic effects produced by intracerebroventricular (icv) and intrathecal (it) administrations.

RESULTS

1) EM-1 raised the pain threshold dose-dependently in tail stimulation-vocalization test in rats and inhibited the writhing responses induced by ip acetic acid in mice. EM-1 also decreased the hyperalgesia in both adjuvant arthritis and neuropathic pain model. 2) The analgesic effect induced by central (icv and it) administration of EM-1 was faster and more powerful than that induced by peripheral (ip) administration. 3) The analgesic effect of EM-1 was reversed by naloxone (opioid receptor antagonist), as well as by cyprodime (mu-opioid receptor selective antagonist). Repeated administrations of EM-1 induced tolerance.

CONCLUSION

EM-1 had a definite analgesic effect and the analgesic effect of EM-1 was mediated by central mu-opioid receptor.

A mechanism of Ca2+ release from Ca2+ stores coupling to the Na+/Ca2+ exchanger in cultured smooth muscle cells

We previously observed Ca2+ release from intracellular Ca2+ stores caused by reduction in extracellular Na+ concentration ([Na+]o). The purpose of this study was to determine whether lowering [Na+]o can elicit Ca2+ release from Ca2+ stores via the Na+/Ca2+ exchanger and to elucidate the mechanisms related to the Ca2+ release pathway in cultured longitudinal smooth muscle cells obtained from guinea pig ileum. Low [Na+]o-induced Ca2+ release was inhibited by antisense oligodeoxynucleotides for Na+/Ca2+ exchanger type 1 (anti-NCX). Application of anti-NCX to cells attenuated both the number of Ca2+ responding cells and the expression of the exchanger. Moreover, microinjection of heparin, a blocker of inositol 1,4,5-trisphosphate (IP3) receptors, into the cells inhibited low [Na+]o-induced Ca2+ release. These findings suggest that low [Na+]o-induced Ca2+ release occurs through an IP3-induced Ca2+ release mechanism due to changes in the Ca2+ flux regulated by the Na+/Ca2+ exchanger.

Modulation of Th2 type cytokine production from human peripheral blood leukocytes by a macrolide antibiotic, roxithromycin, in vitro

The influence of a macrolide antibiotic, roxithromycin (RXM), on Th1 and Th2 cytokine productions from human peripheral blood T cells was examined under stimulation with co-stimulatory molecules. Peripheral blood T cells prepared from both healthy and allergic rhinitis donors were cultured in the presence of RXM on anti-CD3 mAb and anti-CD26 mAb-coated wells, anti-CD3 mAb and anti-CD28 mAb-coated wells, and anti-CD3 and PMA. T-cell proliferation, along with the concentration of interleukin (IL)-2, interferon (IFN)-gamma, IL-4 and IL-5 were measured. RXM did not affect T-cell proliferation induced by several ways of co-stimulatory activation as assessed by 3H-thymidine incorporation into DNA. RXM also had no effect on IL-2 and IFN-gamma secretion by T cells prepared from both healthy and allergic rhinitis donors. On the other hand, RXM markedly inhibited both IL-4 and IL-5 secretions under each of the co-stimulatory conditions in a dose-dependent manner. These results indicate that RXM inhibits specifically Th2 cytokine secretion from T cells induced by co-stimulatory molecule stimulations. This inhibitory action of RXM may be partially responsible for attenuating effect of the agent on the inflammatory diseases.

Enhancement of endogenous corticosterone levels by a macrolide antibiotic, roxithromycin in mice

The influence of roxithromycin (RXM), a macrolide antibiotic, on endogenous corticosterone (CS) levels was examined in BALB/c mice. Mice were sensitized intraperitoneally with two doses of Keyhole Limpet Hemocyanin at 1 week intervals. Mice were given orally 2.5 mg/kg RXM once a day for 14 days starting 7 days after the first sensitization. RXM administration caused markedly increase in endogenous plasma CS levels which was peaked at 60 min after the administration. However, josamycin did not influence on endogenous CS levels in plasma. Injection of dexamethasone inhibits the plasma CS hyperproduction induced by RXM treatment.

[Effectiveness of Saiko-Keishi-To (TJ-10, a Kampo herbal medicine) for trigeminal neuralgia in rats]

It is known that Saiko-Keishi-To (TJ-10), a Kampo herbal medicine used for the treatment of epilepsy, shows a satisfactory curative effect even in the patients suffering from trigeminal neuralgia. To verify the effectiveness of TJ-10, Wistar rats with chronic neuralgia of the mandibular nerve were prepared and TJ-10 was administered to them for 4 weeks following the manifestation of pain in the mandibular region. The result reveals that the rise in the pain threshold in the mandibular region is more significant in the rats administered TJ-10 than in those in the control group. However, in the tail flick test, no significant change was observed in the pain threshold. These findings suggest that TJ-10 is effective for controlling the manifestation of pain in ligatured nerves, by local effect, not by general analgesic effect.

The inhibitory effect of serotonin on the spontaneous discharge of suprachiasmatic neurons in hypothalamic slice is mediated by 5-HT(7) receptor

The effects of serotonin (5-HT) receptor agonists and antagonists on the spontaneous discharge of suprachiasmatic nucleus (SCN) neurons were investigated using rat hypothalamic slice. It was found that: (1) the SCN neurons showed a persistent rhythm in the spontaneous discharge rate, which was higher during the light phase than during the dark phase; (2) the effects of 5-HT on SCN neurons was inhibitory in nature and the sensitivity of SCN neurons to 5-HT during the light phase was lower than that during the dark phase; (3) both 5-HT and 5-HT(1/7) receptor agonist, (+/-)-8-hydroxy-2-(DL-N-propylamino) tetralin hydrobromide, could inhibit the spontaneous discharge of SCN neurons. This inhibitory effect could be blocked by 5-HT(2/7) receptor antagonist ritanserin and putative 5-HT(7) receptor antagonists clozapine, but neither by selective 5-HT(2) receptor antagonist ketanserin, nor by 5-HT(1) receptor antagonist pindolol. It was suggested that the inhibitory effect of 5-HT on the spontaneous discharge of SCN neurons in rat hypothalamic slice is mediated by 5-HT(7) receptor subtype.

[Intracellular calcium kinetics after odorant stimulus in olfactory receptor cells isolated from mice]

cAMP and IP3 act as secondary messengers in olfactory signal transduction and when activated, stimulate calcium levels in olfactory receptor cells. Little is known however, about the causal mechanism. We studied calcium kinetics in mouse olfactory receptor cells after odorant stimuli. Olfactory receptor cells were isolated from female BALB/c mice, treted with trypsin, and stained with Fura-2/AM. Changes in intracellular Ca2+ concentrations in stained cells were measured with a fluorescent microscopic image-processing device (ARGUS-50; Hamamatsu Photonix, Japan). We found that intracellular Ca2+ concentrations rose after exposure to a set of odorants, including 3-ethoxy-4-hydroxy-benzaldehyde, caprylic acid, heptanoic acid, nonanoic acid, eugenol, phenethyl alcohol, and n-amyl acetate. Adding 2', 5'-dideoxyadenosine, a cAMP inhibitor, beforehand suppressed olfactory receptor cell response to odorants. Intracellular Ca2+ concentrations increased substantially in response to stimulation by odorants in calcium-free Ringer's solution, but only a slight increase was seen in intracellular calcium concentration in response stimulation by a high concentration of K+ (145.6 mM) in calcium-free Ringer's solution. The increase in intracellular Ca2+ concentration after odorant stimuli was suppressed when olfactory receptor cells were pretreated with ryanodine, which releases Ca2+ from intracellular stores. These findings suggest that elevated Ca2+ concentrations may be involved in releasing Ca2+ from intracellular calcium stores in mouse olfactory receptor cells, in which cAMP functions as a secondary messenger in olfactory signal transduction.

[Splenic natural killer cell activity is suppressed by ligation of unilateral mental nerve in rats]

It has been reported that surgical procedures and postoperative pain suppress immune activities of the patient. But it is not clear if chronic pain in a small area affects immune activities. We prepared rats with chronic neuralgia of the mental branch originating from the mandibular nerve (a division of the trigeminal nerve) and examined the change of splenic NK-cell activity. Surgical procedures to prepare rat models for the study were as follows: one mental nerve was exposed and ligated at the mental foramen in order to create hypersensitivity in the ipsilateral innervated area. Splenic NK-cell activity 3 weeks after the surgery was reduced significantly in the operation group than that of the sham-operation group and the non-operated control group. The result suggests that the immune functions are remarkably affected by chronic pain evoked in a limited area such as the area innervated by the mental nerve.

The inhibitory effect of anti-allergic agent suplatast tosilate (IPD-1151T) on methacholine- and allergen-induced bronchoconstriction in sensitized mice. asakazu@med.showa-u.dc.jp

The influence of an anti-allergic agent, suplatast tosilate (IPD-1151T; (+/-)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenyl-carbamoyl]-ethyl] dimethylsulfonium p-toluenesulfonate) on allergic bronchoconstriction induced by allergen and methacholine (MCh) were examined in mice. BALB/c mice were sensitized by intraperitoneal injection of dinitrophenylated-keyhole limpet hemocyanin (DNP-KLH) mixed with A1(OH)3 (DNP-KLH). IPD-1151T was administered orally once a day for either 5 or 14 days in doses of 10, 30 or 100 mg/kg. Bronchoconstriction was measured 24h after the final drug administration. IPD-1151T inhibited both antigen- and MCh-mediated bronchoconstriction in actively sensitized mice. The inhibition induced was closely related to the dose and frequency of oral administration of the agent. We also examined the effect of IPD-1151T on IgE production in response to DNP-KLH immunization. IPD-1151T inhibited dose-dependently both total and specific IgE concentrations in serum prepared from mice 15 days after immunization. These results strongly indicate that IPD-1151T inhibits IgE production in vivo and results in attenuating effect on bronchoconstriction.

Suppressive effects of co-stimulatory molecule expressions on mouse splenocytes by anti-allergic agents in vitro

The influence of anti-allergic drugs, epinastine hydrochloride (EP) and disodium cromoglycate (DSCG), on the co-stimulatory molecule expression was examined using in vitro cell culture technique. Spleen cells obtained from BALB/c mice 10 days after immunization with haemocyanin absorbed to aluminium hydroxide were cultured in the presence of 100.0 microg/ml haemocyanin and various concentrations of the agents. Low concentrations (<1.5 x 10(-4)M) of EP and DSCG did not influence spleen cell blastic activity induced by antigenic stimulation, whereas these agents caused significant inhibition of spleen cell activation when 2 x 10(-4) M of the agents were added to cell cultures. EP and DSCG also did not affect blastic activity of sensitized splenic T cells by anti-CD3 monoclonal antibody stimulation even when these cells were cultured in the presence of 2 x 10(-4) M of the agents. We next examined the influence of EP and DSCG on the expression of co-stimulatory molecules on spleen cells in response to antigenic stimulation. Sensitized spleen cells were cultured in the presence of 2 x 10(-4)M of the agents and the expression of molecules were examined by flow cytometer 24h later. EP and DSCG suppressed the expression of costimulatory molecules, CD40 and CD80, but not CD86, on splenic B cells which were enhanced by antigenic stimulation in vitro.

Suppressive effects of azelastine hydrochloride on CD40 expression in mice

The present study was designed to examine the influence of an anti-allergic agent, azelastine hydrochloride (AZ) on a co-stimulatory molecule, CD40 expression in actively sensitized mice. BALB/c mice were sensitized by intraperitoneal injection of two doses of dinitrophenylated-ovalbumin and Al(OH)3 at one-week intervals. The mice were treated orally with 0.1 mg/kg of AZ once a day for 14 days starting the same day of booster sensitization. AZ treatment of mice caused the significant suppression of total serum IgE concentration on Day 21 after the first sensitization. However, AZ treatment scarcely affected IL-4 concentration in aqueous spleen extracts. Flowcytometric analysis revealed the suppressive effects of AZ on CD40 expression on sensitized-spleen cells. These data may suggest that AZ suppresses the production of IgE through the inhibition of CD40 expression.

Influence of anti-allergic agents on in vivo expression of co-stimulatory molecules in normal mice

The co-stimulatory signal provided by the interaction between CD28 and its ligands, CD80 and CD86, is critical for T cell activation. Engagement of CD40 and CD40L is also essential for IgE synthesis and secretion. In the present study, we examined the influence of anti-allergic drugs on co-stimulatory molecule (CD40, CD80 and CD86) expression in normal mouse splenocytes by flow cytometry. Treatment of BALB/c mice with azelastine (AZ) at a dose of 50.0 micrograms/kg/day, which is the most effective therapeutic dose, for two weeks scarcely affected the expression of co-stimulatory molecules CD40, CD80 and CD86 on splenocytes, whereas a three-week treatment strongly suppressed the expression of these molecules. We also examined the influence of terfenadine (TR) on co-stimulatory molecule expression. The expression of molecules on splenocytes was inhibited when donor mice were treated orally with 2.0 mg/kg/day of TR for three weeks. However, it was not inhibited during a two-week period treatment. These results suggest that the attenuating effects of anti-allergic agents on the diseases may be explained, in part, by their inhibitory action of co-stimulatory molecule expression.

Inhibitory effect of electroacupuncture on murine collagen arthritis and its possible mechanisms

The influence of electroacupuncture (EA), a traditional Chinese medical treatment, on type II collagen-induced arthritis (CIA) was examined in DBA/IJ mice in vivo. Mice were immunized intradermally twice at a 3-week interval with bovine type II collagen (C II). EA stimulation, begun on day 21 simultaneously with the second immunization, was applied at the acupoint equivalent to GV4 three times a week for 3 weeks. The results showed that EA delayed the onset, attenuated the severity of arthritis, and reduced the anti-collagen antibody level. Furthermore, we investigated the impact of EA on the productions of endogenous interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2), and the levels of IL-1 beta mRNA in splenocytes and synovial tissues from C II immunized mice on day 45 and cyclooxygenase-2 (COX-2) mRNA in lipopolysaccharide (LPS)-stimulated macrophages of normal mice by using reverse transcriptase-polymerase chain reaction (RT-PCR). EA stimulation significantly inhibited the concentrations of splenic endogenous IL-1 beta and serum PGE2. The expression of IL-1 beta mRNA in spleen cells was obviously down-regulated and that in synovial tissues was modestly affected by EA. COX-2 mRNA was highly expressed in cultured peritoneal macrophages when stimulated with LPS. Previous treatment with EA also reduced LPS-stimulated induction of COX-2 mRNA. These data suggest that EA has an inhibitory effect on murine CIA, and the partial mechanism of its therapeutic result may be attributed to inhibiting the productions of IL-1 beta and PGE2 by suppressing the IL-beta and COX-2 gene activations.

[Denervation of the cervical sympathetic nerve inhibited the splenic natural killer cell activity by modulation of the splenic sympathetic nerve activities in rats]

It is known that the splenic natural killer cell (NK) activity 4 weeks after unilateral resection of the cervical sympathetic nerve (csn) is significantly lower than that after sham operation in rats. To investigate the role of the splenic sympathetic nerve, the splenic NK activity after csn was compared in the control animals (n = 9) and the splenic sympathetic nerve denervated animals (n = 8). The splenic NK activity in control group was reduced significantly after csn, whereas that in splenic nerve denervated group did not reveal significant change after csn. The results suggest that the reduction of the splenic NK activity after csn is induced through the modulation of the splenic sympathetic nerve activities.

Production of hydrogen peroxide in cancerous tissue by intravenous administration of sodium 5,6-benzylidene-L-ascorbate

We investigated whether the antitumor action of sodium 5,6-benzylidene-L-ascorbate (SBA) is mediated via oxidation-involved mechanism, in three different systems: 3'-methyl-4-dimethylaminoazobenzene (DAB)-induced rat hepatocellular carcinoma (in vivo), its homogenate (semi in vivo), and cultured cells (in vitro). Oral intake of DAB irreversibly produced hepatocellular carcinoma in rats, with a maximum incidence of carcinogenesis after 4 months. Intravenous administration of SBA induced vacuolar, eosinophilic degeneration and nuclear debris, producing greater amounts of ESR signal of ascorbate radical and hydrogen peroxide (H2O2)-derived chemiluminescence (CL) (H2O2-CL) in the cancerous tissue than in the normal tissue. When SBA was directly added to the homogenates, higher amounts of ascorbate radical and H2O2-CL were generated in cancerous tissues. When SBA was added to the RPMI1640 medium supplemented with 10% fetal bovine serum, methionine was oxidized to methionine sulfoxide and H2O2 was produced in amounts that sufficiently induce apoptotic cell death in human promyelocytic leukemic HL-60 cells. Cytotoxic activity of SBA was significantly reduced by catalase. These data suggest that antitumor activity of SBA in vivo might at least in part be due to H2O2, produced from SBA.

Suppressive activity of a macrolide antibiotic, roxithromycin, on pro-inflammatory cytokine production in vitro and in vivo

This study was designed to examine the influence of a macrolide antibiotic, roxithromycin (RXM), on the production of pro-inflammatory cytokines, interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. In the first experiments, we examined the effect of RXM on in vitro cytokine production from lipopolysaccharide (LPS)-stimulated human peripheral blood monocytes. The monocytes were cultured in the presence of various doses of the agent. After 24 h, the culture supernatants were obtained and assayed for IL-1beta and TNF-alpha contents by enzyme-linked immunosorbent assay. RXM suppressed the in vitro production of IL-1beta and TNF-alpha in response to LPS stimulation. This was dose dependent and first noted at a concentration of as little as 0.05 microg/ml, which is much lower than therapeutic blood levels. In the second part of the experiments, we examined the influence of RXM on the appearance of IL-1beta and TNF-alpha in mouse lung extract induced by LPS inhalation. RXM was administered orally into BALB/c mice at a single dose of 2.5 mg/kg once a day for 5-12 weeks. These mice were then instilled with LPS into the trachea and examined for the presence of cytokines in aqueous lung extracts. Pretreatment of mice with RXM for 5 weeks did not influence of the appearance of both IL-1beta and TNF-alpha in aqueous lung extracts. However, pretreatment for more than 7 weeks dramatically suppressed the cytokine appearance in the extracts.

Suppressive activity of the chloroform extract of Tripterygium wilfordii Hook f on effector T cell activation during Hymenolepis nana infection in mice

The chloroform extract of Tripterygium wilfordii Hook f (TWH extract) administered into mice daily at doses of 80.0 to 200.0 micrograms/kg (but not 40.0 micrograms/kg) caused suppression of protective immunity to Hymenolepis nana when the extract was injected subcutaneously during the induction phase of protective immunity. Daily administration of 200.0 micrograms/kg TWH extract, during the course of larval development from challenge, also suppressed protective immunity. Inhibition of protective immunity was only observed in mice that received TWH extract for 6 days at a daily dose of 200.0 micrograms/kg and were challenged 24 h after the final injection. TWH extract did not inhibit formation of effector cells that mediate delayed type hypersensitivity (DTH) to H. nana egg antigen when the extract was administered subcutaneously at a dose of 200.0 micrograms/kg/day for 5 days before cell preparation. However, TWH extract did inhibit DTH effector cell activation when cells prepared from infected, PBS-injected mice were transferred into 200.0 micrograms/kg TWH extract-treated recipient mice. These results strongly indicate that TWH extract cannot inhibit the generation of effector cells but will suppress their function in vivo.

Role of endogenous interferon-gamma on the enhancement of splenic NK cell activity by electroacupuncture stimulation in mice

Successive electro-acupuncture (EA) stimulation applied to bilateral anterior tibial muscles, where Zusanli (ST36) acupoints are located, once a day (30 min) for 3 successive days significantly enhanced splenic natural killer (NK) cell activity in BALB/c mice. The percentage of splenic NK cells, as measured by flow cytometry, was not affected in these mice. Interferon (IFN)-gamma level in splenic aqueous extract, prepared from the ST36 acupoint-stimulated mice, was significantly higher than that of the controls. In vivo treatment with neutralizing monoclonal antibody against mouse IFN-gamma completely abrogated the increase in splenic NK cell activity induced by ST36 acupoint stimulation. The same stimulation also significantly increased the concentration of splenic beta-endorphin, which coincided with the significant increase in splenic IFN-gamma production. Pre-administration of 10 mg/kg naloxone before initiation of EA stimulation every day reduced the enhancements of NK cell activity and IFN-gamma level. These observations strongly suggest that endogenous IFN-gamma mediates the up-regulation of NK cell activity by EA stimulation at the ST36 acupoints. Furthermore, endogenous beta-endorphin secreted by EA stimulation also plays an important role in the up-regulation of NK cell function, which may be realized through regulating IFN-gamma production.

Antipyretic action of peripheral stimulation with electroacupuncture in rats

The present study was designed to investigate the antipyretic action of peripheral stimulation with electroacupuncture (EA) in SD rats. EA stimulation was applied for 30 min to the peripheral muscle where the equivalent Quchi (LI11) acupoint is located. We first examined the effects of EA stimulation on fever induced by either lipopolysaccharide (LPS), interleukin-1 beta (IL-1 beta) or prostaglandin E2 (PGE2). Intraperitoneal injection of LPS at a dose of 100 micrograms/kg caused a high rectal temperature, which was suppressed by EA stimulation. EA stimulation also inhibited the development of fever induced by IL-1 beta injection either intravenously or into the preoptic area (POA). The rats that received administration of PGE2 into POA developed rapid and high fevers, which were attenuated by EA stimulation. In the second part of the experiment, we investigated the levels of cytokines and PGE2 during the development of fever. The concentrations of IL-6 and PGE2 but not IL-1 beta, in brain and serum were increased by intraperitoneal injection of 100 micrograms/kg LPS. EA stimulation reduced PGE2 levels in both brain and serum in LPS-injected rats, but failed to change the levels of IL-6. Intravenous injection of IL-1 beta produced high brain and serum PGE2 levels, which were also significantly suppressed by EA stimulation. The results suggest that EA stimulation possesses an antipyretic effect through the inhibition of the action of PGE2 in rats.

Role of hydrogen peroxide in antitumor activity induction by sodium 5,6-benzylidene-L-ascorbate

Role of hydrogen peroxide (H2O2) in the induction of antitumor activity against chemically-induced rat hepatocellular carcinoma by sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated. ESR spectroscopy demonstrated that rat liver homogenate of cancerous tissue significantly enhanced the radical intensity of SBA more potently than that of precancerous or normal tissue. The peroxyoxalate chemiluminescence method demonstrated that SBA significantly enhanced the production of H2O2-derived chemiluminescence intensity in the liver homogenates, and the effect of SBA was greater in cancerous tissue than in precancerous or normal tissue. Addition of ascorbic acid, a degradation product of SBA, showed similar but slightly weaker stimulation effects. These data suggest that antitumor activity of SBA in vivo might, at least in part, be due to H2O2 production.

Influence of moxibustion on collagen-induced arthritis in mice

The influence of moxibustion, a traditional Chinese medical treatment; on type II collagen-induced arthritis (CIA) was examined in DBA/1J mice in vivo. Mice were immunized intradermally twice at 3-week intervals with bovine type II collagen (C II). The main incidence of arthritis started around day 30 and lasted to day 60 after the first immunization. Moxibustion, using three different regimens, was applied at the acupoint equivalent to GV4 every other day. Moxibustion, from day 0 to day 30 after the first immunization, suppressed the onset and development of arthritis, as well as anti-collagen antibody level. Treatment with moxibustion, from the day 31 to day 60, also resulted in a significant inhibition of progression of arthritis and production of anti-C II antibody. Furtherfore we examined the influence of moxibustion on the established arthritis. Moxibustion given from day 61 to day 120, mildly but significantly decreased the anti-C II antibody level in diseased mice, while the bone erosion and joint destruction were not affected. These results indicate that moxibustion could prevent the incidence and attenuates the development of murine CIA.

Suppressive effects of Tripterygium wilfordii Hook f., a traditional Chinese medicine, on collagen arthritis in mice

The effect of chloroform extract of Tripterygium wilfordii Hook f. (TWH extract), a traditional immunosuppressive Chinese herb, on type II collagen (C II)-induced arthritis (CIA) in DBA/1J mice was studied. In the first set of experiments, we examined the effect of TWH extract on cellular immune responses to C II. As compared with mice treated with saline, TWH extract administered orally at doses of more than 400 microg kg(-1) once a day for 14 days inhibited the ability of inguinal lymph node cells to produce T cell cytokines interleukin-2 and interferon-gamma when the cells were obtained from mice 21 days after immunization and cultured in vitro with C II. Treatment with TWH extract also inhibited production of macrophage cytokines interleukin-1beta and tumor necrosis factor-alpha in response to in vitro stimulation of lymph node cells with C II. In the second part of the experiment, we evaluated the influence of TWH extract on the incidence and development of arthritis in murine CIA. Mice were immunized twice at a 3-week interval with bovine C II, with TWH extract being given orally once a day for 14 days with four different regimens. A 14-day course of TWH extract treatment at a daily dose of 400 microg kg(-1), which began on the day of the first C II immunization, suppressed the development of arthritis, as well as antibody production and delayed-type hypersensitivity to C II. Treatment with TWH extract, which started on the same day as the booster immunization, also resulted in inhibition of development of arthritis and of immune responses to C II. On the other hand, therapeutic administration with TWH extract did not affect the clinical course of the disease and the immune response to C II.

Inhibition of murine chronic graft-versus-host disease by the chloroform extract of Tripterygium wilfordii Hook f

The effects of chloroform extract of Tripterygium Wilfordii Hook f (TWH extract) on chronic graft-versus-host disease (GVHD) were examined in a murine experimental model. Chronic GVHD was induced by intravenous transfer of parental DBA/2 spleen cells into unirradiated (C57BL/6 x DBA/2)F1 recipient mice. The effects of TWH extract on GVHD were assessed by measuring both the degree of splenomegaly and the total serum IgE levels 3 weeks after the cell transfer. Subcutaneous administration of TWH extract once a day for 3 weeks suppressed chronic GVHD in a dose-dependent manner. Significant suppression of splenomegaly was first noted in mice treated with 7.5 micrograms/kg of the agent. The maximum inhibition was observed when mice were treated with more than 10.0 micrograms/kg (but not 5.0 micrograms/kg) caused complete suppression of serum IgE hyperproduction. The ability of donor T cells purified from recipient spleen cells to produce interleukin 4 in response to stimulation with anti-CD3 monoclonal antibody was significantly abrogated when recipient mice were treated with 10.0 micrograms/kg of the agent. These results strongly suggest that TWH extract will be an addition to the cohort of immunosuppressive therapies used in solid organ and bone marrow transplantation.

Effect of physiological fluids on radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate

The effect of various physiological fluids on the radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated using ESR spectroscopy. Blood from various animals did not significantly affect the radical intensity of both ascorbates, whereas the corresponding plasma fractions significantly enhanced the radical intensity. This suggests that some populations of blood cells might modify the interaction between plasma components and ascorbates. Saliva contained labile substance(s) which effectively reduced the ascorbate radical intensity. HPLC demonstrated the presence of endogenous ascorbate in rat liver and brain homogenates. When sodium ascorbate or SBA was incubated with any of these homogenates, their radical intensity was synergistically enhanced, but abruptly declined without any apparent ascorbate degradation. Incubation with homogenates elevated the radical intensity of SBA up to the level significantly higher than that of sodium ascorbate. The present data suggest that antitumor action of SBA might be mediated via the accelerated production of ascorbate radical in the target organ.

Induction of apoptotic cell death in human leukemic cell line, HL-60, by extremely low frequency electric magnetic fields: analysis of the possible mechanisms in vitro

The influence of extremely low frequency electric magnetic fields. (ELF EMFs) on apoptotic cell death was examined using a human leukemic cell line, HL-60 and normal human peripheral blood leukocytes. When HL-60 cells were exposed to 45 mT ELF EMFs, apoptotic cell death, characterized by cell shrinkage, nuclear fragmentation and cleavage of internucleosomal DNA to yield fragments that were multiples of 180-200 base pairs, were induced. The minimum periods required apoptotic HL-60 cell death was 1.0 hour. However, exposure to ELF EMFs could not produce detectable DNA fragmentation in human peripheral blood leukocytes. Static magnetic fields could not induce apoptotic cell death in HL-60 cells, even when the cells were exposed to 180 mT of magnetism for 3.5 hours. We further examined whether hyperthermia induced by induction current in ELF EMFs produced apoptosis in HL-60 cells. Induction current in ELF EMFs enhanced temperature of culture medium to 40.3 degrees C at 3.0 hours of exposure. However, this level of temperature could not induced apoptotic cell death in HL-60 cells, even when cells were cultured for 3.5 hours. These results suggest that induction current produced by ELF EMFs may be one of main mediator in apoptosis in HL-60 cells.

Induction of apoptosis in human leukemic cells by magnetic fields

When human myelogenous leukemic cell lines, HL-60 and ML-1, were exposed to 50 Hz electromagnetic fields (EMFs), nucleosome-sized DNA fragmentation (a biochemical marker of apoptosis) was induced as assessed by agarose gel electrophoresis. However, EMFs could not induce detectable DNA fragmentation in either human peripheral blood leukocytes or polymorphonuclear cells. The minimum exposure period required for the onset of DNA fragmentation in leukemic cells was 1.0 h. Although adverse effects of EMFs on human health have been reported, the apoptosis-inducing action of EMFs on leukemic cells may suggest a possible medical application.

Enhancement of splenic interferon-gamma, interleukin-2, and NK cytotoxicity by S36 acupoint acupuncture in F344 rats

The effect of Tsusanli acupuncture point (S36 acupoint) stimulation on splenic natural killer (NK) cytotoxicity was examined in Fischer 344 (F344) rats. Electro-acupuncture stimulation (voltage intensity, 1 to 5 V; duration, 1 ms; frequency, 1 Hz) was applied to bilateral S36 acupoints once a day (1 h) for 3 d. NK cytotoxicity was measured by the standard 4-h 51Cr release assay. Successive acupuncture treatment for 3 d significantly enhanced splenic NK cytotoxicity (p < 0.001) on the first day after final treatment as compared to that of the control. However, similar stimulation to abdominal muscle did not influence splenic NK cytotoxicity. We also examined endogenous cytokine activities in aqueous spleen extracts prepared from acupunctured and control rats. The extracts from rats acupunctured at the S36 acupoint contained high levels of interleukin (IL)-2 and interferon (IFN)-gamma as compared to those of abdominal muscle acupunctured and non-acupunctured control rats (p < 0.01). Furthermore, a significant positive correlation (p < 0.01) was observed between the levels of each cytokine tested and splenic NK cytotoxicity. The same positive correlation was also observed between the levels of IL-2 and IFN-gamma (p < 0.01). These observations indicate that electro-acupuncture stimulation of the S36 acupoint enhances splenic NK cytotoxicity and that IL-2 and IFN-gamma may function, at least in part, in the regulation of NK cell activity in this system.

The expression of mRNA for a kappa opioid receptor in the substantia nigra of Parkinson's disease brain

We molecularly cloned the kappa opioid receptor from a human substantia nigra cDNA library. When expressed in HEK293 cells, the cloned receptor had similar pharmacological characteristics to the rat kappa opioid receptor. Northern blot analysis showed the presence of a single transcript of about 6 kb in size for mRNA prepared from the substantia nigra. Using in situ hybridization histochemistry, we studied the expression of this receptor in postmortem human brains from control and Parkinson's disease subjects. Kappa opioid receptor mRNA was present in melanized (possibly dopaminergic) neurons of the substantia nigra and the nucleus paranigralis. On the other hand, Parkinson's disease brains had markedly fewer melanized neurons, as expected, and correspondingly very low or background levels of mRNA for the kappa opioid receptor. However, in some cases, remaining melanized neurons still expressed the receptor mRNA. From these results we suggest that dopaminergic neurons in the human substantia nigra and the nucleus paranigralis synthesize kappa opioid receptors and express them in their perikarya and their terminal regions. The kappa opioid receptor expressed in the melanized neurons may play a role in the normal function of dopaminergic systems and possibly in the etiology of Parkinson's disease.

Emission of extremely strong magnetic fields from the head and whole body during oriental breathing exercises

This article reports the result of an experiment that was designed to measure the biomagnetic field emanating from two individuals who were practising traditional Oriental Qi Gong breathing exercises. The biomagnetic field was measured with differential coils wound 80,000 turns, a magnetic needle compass and a digital electromagnetic wave detection device. It was found that an extremely strong magnetic field was emitted from the two individuals. One subject emitted a magnetic field at the level of 200-300 mT (2-3 mGauss) and the other at 0.13 mT (1.3 mGauss). In both cases, moreover, the magnetic needle compass rotated 30 degrees (this was tested 32 times). When the rotation of the needle occurred, a reproducible magnetic field of 800-1500 mT (8-15 mGauss) was indicated on the digital measuring device (this was tested 12 times). It is concluded that traditional Oriental Qi Gong breathing appears to stimulate an unusually large biomagnetic field emission.

[Denervation of the cervical sympathetic nerve inhibited the splenic natural killer cell activity in rats]

Repeated applications of stellate ganglion block (SGB) are known to improve symptoms of allergic rhinitis but the mechanism of the effects is not clear. Correlation between nervous system and immune system has been reported. To examine if the blockade of a part of the sympathetic nervous system like SGB could affect immune system activity of whole body, YAC 1 cell lytic activities of the splenic natural killer cell (NK activity) were compared between the sham operation group (n = 12) and the cervical sympathetic denervation group (n = 10) 4 weeks after the operation. NK activity of denervation group was significantly lower than that of sham group. The result suggests the possibility of modulation of the immune activity of individuals by partial blockade of the sympathetic nervous system.

Acupuncture stimulation enhances splenic natural killer cell cytotoxicity in rats

Acupuncture stimulation of the anterior tibial muscle, which is equivalent to Tsu-sanli point (S36) stimulation and which induces acupuncture analgesia, enhanced YAC-1 cell lytic activity of the splenic natural killer cells (NK activity) from pentobarbital anaesthetized Wistar rats. On the other hand, abdominal muscle stimulation, which does not induce acupuncture analgesia, did not affect NK activity. The serum from rats treated with acupuncture stimulation (acupuncture-stimulated rats) also enhanced the NK activity of other intact rats. The reinforcement effect of serum remained after heat inactivation (56 degrees C, 30 min). The serum from acupuncture-stimulated rats also had more potent complement activity than that from control rats. These results indicate the following considerations: 1) the Tsu-sanli point may be one of the specific points modulating immune activity, 2) this immune modulation system may share a common nervous pathway with the acupuncture analgesia-producing system, 3) acupuncture stimulation may modify NK activity through unknown heat stable humoral factors as well as the nervous system, and 4) acupuncture stimulation may activate the complement system.

Functional coupling of the Na+/Ca2+ exchanger with Ca2+ release from intracellular stores in cultured smooth muscle cells of guinea pig ileum

The mechanism of increase in intracellular Ca2+ concentration ([Ca2+]i) by removal of extracellular Na+, which phenomena were reported previously (Japan. J. Pharmacol. 63 83-91 1993), was investigated in cultured guinea pig ileum longitudinal muscle cells loaded with a fluorescent Ca2+ indicator, fura-2, by digital ratio imaging microscopy. Isotonic substitution of choline chloride for NaCl induced a transient increase in [Ca2+]i. The pretreatment of thapsigargin (0.5 microM), but not nicardipine (10 microM), suppressed the transient increase completely. In solutions containing micromolar concentrations of free Ca2+ (nominally Ca2+-free solution), the Na+-free induced transient increase was observed, but neither the second cell exposure to the Na+-free solution nor the following application of histamine increased [Ca2+]i, indicating that removal of extracellular Na+ releases Ca2+ from intracellular stores including inositol 1,4,5-trisphosphate (IP3)-releasable pools. The Na+-free induced transient increase required the presence of more than micromolar concentrations of extracellular free Ca2+ and releasable Ca2+ within the stores, but ryanodine did not affect the transient increase. These results suggest that undetectable influx of Ca2+ by the reverse-mode action of the Na+/Ca2+ exchanger can release Ca2+ from the thapsigargin-sensitive intracellular stores including IP3-releasable pools.

Increased c-fos expression in spinal neurons induced by electrical stimulation of the ureter in the rat

The spinal processing of afferent input from the ureter was examined using an immunocytochemical technique to detect the expression of c-fos, an immediate early gene. Proximal and distal sites in one ureter were electrically stimulated separately or together at intensities that elicited a pseudo-affective response (an increase in arterial pressure). Very few Fos+ cells (range: 0.6-6.6 cells/half section were present in the L(1)-L(2), L(5)-S(2) spinal segments in sham operated control animals; however, following stimulation of the ureter, a significant increase in the numbers of Fos+ cells was detected at spinal levels L(1)-L(2) (mean 24.5-33.1 cells/half section) and L(6)-S(1) (mean 17.4-33.0 cells/half section). In L(6)-S(1), the numbers of Fos+ cells were significantly greater ipsilateral (mean 25.2 cells/half section) vs. contralateral (12.3 cells/half section) to stimulation; whereas in L(1)-L(2), the numbers were similar on both sides of the spinal cord. In L(1)-L(2), a greater percentage of Fos+ cells was present in superficial medial (MDH, 49.7%) and lateral dorsal horn (LDH, 40.8%); whereas in L(6)-S(1), the cells were more numerous in sacral parasympathetic nucleus (SPN, 38.7%) and LDH (25.6%*) regions. This distribution of Fos+ cells varies in a number of respects from that noted in previous experiments after chemical irritation of the urinary bladder and urethra which activated neurons only in L(6)-S(1) and primarily in the DCM and MDH. The results indicate that nociceptive afferent inputs from different areas of the urinary tract are processed in different regions of the spinal cord.

Non-NMDA glutamatergic excitatory transmission in the descending limb of the spinobulbospinal micturition reflex pathway of the rat

I.v. administration of GYKI-52466, a non-competitive AMPA/kainate glutamatergic receptor antagonist, inhibited bladder contractions elicited by electrical stimulation in the pontine micturition center (PMC) in urethane-anesthetized rats. The mean threshold dose of GYKI-52466 was 2 mg/kg i.v. (range = 1-4 mg/kg). Maximum inhibition (mean = 57.7 +/- 8.2%, range = 24-83.3% of control) occurred at a dose of 8 mg/kg. CNQX, a competitive AMPA/kainate glutamatergic receptor antagonist, did not significantly alter the evoked contractions. These results indicate that AMPA/kainate receptors are involved in bulbospinal excitatory pathway from the PMC to the parasympathetic nucleus in the lumbosacral spinal cord in the rat.

Suppressive effects of central opioids on delayed type hypersensitivity to trinitrochlorobenzene: comparative study with morphine and electroacupuncture

We reported previously that electroacupuncture (Acu) applied to the acu-point equivalent to GV4 in the mouse just before the 2,4,6-trinitrochlorobenzene (TNCB) challenge suppressed the delayed type hypersensitivity (DTH) through endogenous opioidergic systems in the brain, and the pituitary was pivotal in this immunosuppression. The purpose of the present study was to compare the suppressive effects of Acu with those of single, acute doses of morphine on TNCB-DTH in intact and hypophysectomized (HPX) mice. Subcutaneous morphine 10 mg/kg in ddY mice, 30 mg/kg in BALB/c mice or intracisternal morphine 40 micrograms/mouse in BALB/c mice given just before TNCB challenge suppressed (40-53%) the maximal extent of ear swelling at 24 hrs after challenge in intact mice. In HPX mice, the suppressive effects of intracisternal morphine 10 and 100 micrograms/mouse were less pronounced than those observed in intact mice and there was no significant difference between intact and HPX groups. In addition, suppressive effects observed with Acu or subcutaneous morphine (30 mg/kg) were effectively antagonized by pretreatment with intracisternal naloxone at a dose of as low as 2 micrograms/mouse. Naloxone alone had no effect of its own. These results suggest that 1) the activation of opioid receptor-mediated pathways in the brain, which occurs when opioids are endogenously released (Acu) or exogenously given (morphine), is important in the suppression of TNCB-induced DTH, a cell-mediated immune response, and 2) the pituitary is less pivotal in the suppressive effects of acute morphine than in those of Acu.

Role of glutamate and NMDA receptors in the descending limb of the spinobulbospinal micturition reflex pathway of the rat

MK-801, an NMDA receptor antagonist administered intravenously or intrathecally to the L6-S1 spinal cord inhibited in a dose dependent manner the amplitude of isovolumetric bladder contractions evoked by electrical stimulation in the pontine micturition center (PMC) in urethane anesthetized rats. The mean threshold dose of MK-801 was 10 +/- 6 micrograms/kg i.v. and 10 +/- 1 micrograms i.t. Bladder contractions were completely inhibited at doses ranging from 300 to 3000 micrograms/kg i.v. and from 18 to 48 micrograms i.t. These data indicate that NMDA glutamatergic receptors play an important role in excitatory transmission in the descending pathway from the PMC to the spinal segmental circuitry involved in the control of the urinary bladder.

Cutaneous hyperalgesia induced by peripheral injection of interleukin-1 beta in the rat

The contribution of the activity of afferent fiber filaments to pain and hyperalgesia after administration of a plantar injection of interleukin-1 beta (IL-1 beta) to the hind-paw skin was investigated by recording action potentials of the rat dorsal root in response to mechanical and thermal stimuli. Touch stimuli were delivered by stroking with a cotton-tipped applicator and thermal stimulation was applied by cooling or heating of the skin. After the administration of IL-1 beta (100 pg-1 microgram), responses to touch, cold, and heat stimulation increased to 143%, 200%, and 392%, respectively, of control values on average. IL-1 beta induced transient spontaneous discharge in 50% of experiments. The effects of IL-1 beta were apparent within 1 min. To examine responses to pressure stimulation, an area of 1 mm2 of the hind-paw skin was pressed by a mechanical stimulator. IL-1 beta (0.1 pg-200 ng) decreased the threshold value to 58% of the control pressure required for firing. IL-1 beta also increased responses to various levels of pressure (range: 1-20 g/mm2). These data suggest that IL-1 beta may play an important role in cutaneous hyperalgesia by activating polymodal receptors to mechanical and thermal stimulation.

All-or-none like responses in increment of cytoplasmic free calcium concentrations to histamine in single smooth muscle cells of guinea pig trachea

Single smooth muscle cells were isolated from guinea pig trachea and cultured for 48 hours. The cells were then loaded with a fluorescent-free calcium indicator, fluo-3. Concentrations of cytoplasmic-free calcium ([Ca2+]i) were determined by using a confocal laser scanning fluorescence imaging system. Cells exposed to histamine at concentrations less than 1.0 microM did not indicate any changes of the fluorescence intensities, but stayed at the basal level of [Ca2+]i. Cells exposed to histamine at a concentration in the range of 1.5 to 10 microM indicated marked increases in [Ca2+]i. A further increase in [Ca2+]i by application of higher concentrations of histamine was not observed. The threshold concentration of histamine to increase [Ca2+]i and peak [Ca2+]i varied from cell to cell. In addition, half-maximal response time was shortened with increasing concentrations of histamine from 1.5 to 100 microM. These results indicate that [Ca2+]i responses to histamine is an all-or-none type in each cell. The heterogeneity in the required threshold concentration of histamine to increase in [Ca2+]i and the concentration dependency in half-maximal response time of histamine-induced [Ca2+]i increase may be related to the graded responses of histamine-induced contractions in preparations of the tracheal tissue.