Biomedical subjects

Y Fukata

Publications and source records attributed to Y Fukata.

At least 37 records · Page 2Linked to original sources

PubMed1997

Formation of actin stress fibers and focal adhesions enhanced by Rho-kinase.

The small guanosine triphosphatase (GTPase) Rho is implicated in the formation of stress fibers and focal adhesions in fibroblasts stimulated by extracellular signals such as lysophosphatidic acid (LPA). Rho-kinase is activated by Rho and may mediate some biological effects of Rho. Microinjection of the catalytic domain of Rho-kinase into serum-starved Swiss 3T3 cells induced the formation of stress fibers and focal adhesions, whereas microinjection of the inactive catalytic domain, the Rho-binding domain, or the pleckstrin-homology domain inhibited the LPA-induced formation of stress fibers and focal adhesions. Thus, Rho-kinase appears to mediate signals from Rho and to induce the formation of stress fibers and focal adhesions.

3T3 Cells↗

PubMed1997

aFGF, endogenous satiety substance, facilitates learning, memory and immune function in aging.

aFGF injection s.c. once a week into SAMP8 was begun at 3 weeks after birth and continued for 10 months. Saline was injected as a control. learning and memory and cellular immunological functions in the aFGF group were enhanced significantly, while those of the saline group deteriorated. 1. The number of cholinergic neurons was decreased by less than 20% and ChAT activity in individual neurons in the medial septum which send monosyonaptic terminals to the hippocampus was significantly decreased in the saline group, but not so much in the aFGF group. 2. The respective densities of muscarinic and aFGF receptors, on the hippocampal neurons were significantly higher in the aFGF group than in the saline group. 3. The LTP in hippocampal slice preparations was significantly facilitated in the aFGF group, but not in the saline group. 4. The DTH, (T cell immune response) measured at the end of the 2nd and 7th months were reduced in the 7th month as compared with the 2nd month in the saline group, but aFGF group protected against this reduction. 5. These results show that aFGF provides protection against impairment of not only learning and memory but also the DTH immunoreactivity in SAMP8.

Aging↗

PubMed1996

Phosphorylation and activation of myosin by Rho-associated kinase (Rho-kinase).

The small GTPase Rho is implicated in physiological functions associated with actin-myosin filaments such as cytokinesis, cell motility, and smooth muscle contraction. We have recently identified and molecularly cloned Rho-associated serine/threonine kinase (Rho-kinase), which is activated by GTP Rho (Matsui, T., Amano, M., Yamamoto, T., Chihara, K., Nakafuku, M., Ito, M., Nakano, T., Okawa, K., Iwamatsu, A., and Kaibuchi, K. (1996) EMBO J. 15, 2208-2216). Here we found that Rho-kinase stoichiometrically phosphorylated myosin light chain (MLC). Peptide mapping and phosphoamino acid analyses revealed that the primary phosphorylation site of MLC by Rho-kinase was Ser-19, which is the site phosphorylated by MLC kinase. Rho-kinase phosphorylated recombinant MLC, whereas it failed to phosphorylate recombinant MLC, which contained Ala substituted for both Thr-18 and Ser-19. We also found that the phosphorylation of MLC by Rho-kinase resulted in the facilitation of the actin activation of myosin ATPase. Thus, it is likely that once Rho is activated, then it can interact with Rho-kinase and activate it. The activated Rho-kinase subsequently phosphorylates MLC. This may partly account for the mechanism by which Rho regulates cytokinesis, cell motility, or smooth muscle contraction.

Animals↗

PubMed1996

Regulation of myosin phosphatase by Rho and Rho-associated kinase (Rho-kinase)

The small guanosine triphosphatase Rho is implicated in myosin light chain (MLC) phosphorylation, which results in contraction of smooth muscle and interaction of actin and myosin in nonmuscle cells. The guanosine triphosphate (GTP)-bound, active form of RhoA (GTP.RhoA) specifically interacted with the myosin-binding subunit (MBS) of myosin phosphatase, which regulates the extent of phosphorylation of MLC. Rho-associated kinase (Rho-kinase), which is activated by GTP.RhoA, phosphorylated MBS and consequently inactivated myosin phosphatase. Overexpression of RhoA or activated RhoA in NIH 3T3 cells increased phosphorylation of MBS and MLC. Thus, Rho appears to inhibit myosin phosphatase through the action of Rho-kinase.

3T3 Cells↗

PubMed1996

Protection against impairment of memory and immunoreactivity in senescence-accelerated mice by acidic fibroblast growth factor.

Subcutaneous injection of aFGF once a week into senescence-accelerated mice (SAM)P8 was begun at 3 weeks after birth and continued for 10 months. Saline was injected as a control. Learning and memory and cellular immunological functions in the aFGF group were enhanced significantly, while those of the saline group deteriorated. 1. The number of cholinergic neurons was decreased by less than 20% and choline acetyltransferase activity in individual neurons in the medical septum which send monosynaptic terminals to the hippocampus was significantly decreased in the saline group, but not so much in the aFGF group. 2. The respective densities of muscarinic and NMDA receptors and the aFGF receptor, i.e., FGFR-1 on the hippocampal neurons were also significantly higher in the aFGF group than in the saline group. 3. The long-term potentiation in the hippocampal slice preparations after a brief tetanic stimulation at the Schaffer collateral/commissural afferents was significantly facilitated in the aFGF group, but not in the saline group. 4. These data indicate the normalization caused by aFGF of the medial septohippocampal circuit, which is necessary for learning and memory. 5. The delayed type hypersensitivity reactions (DTH) in the footpad caused by challenge with trinitrophenyl or sheep red blood cells as measured at the end of the 2nd and 7th months, indicated the T cell immune response. Both types of DTHs were reduced in the 7th month as compared with the 2nd month in the saline group, but the aFGF group was protected against this reduction in accordance with age. 6. These results show that aFGF provides protection against impairment of not only learning and memory but also DTH immunoreactivity in SAMP8. They also indicate a close relationship between learning and memory and T cell immune function.

Aging↗

PubMed1996

A new assay system detecting antibody production and delayed-type hypersensitivity responses to trinitrophenyl hapten in an individual mouse.

A new assay system detecting antibody production and delayed-type hypersensitivity (DTH) responses to trinitrophenyl hapten in an individual mouse (AS-DAD) was established. BALB/c mice were immunized intraperitoneally with varying amounts of 2,4,6-trinitrophenylated sheep red blood cells (TNP-SRBC) on day 0. Venous blood was collected on days 2, 4, 6, 8 and 10. Levels of anti-TNP IgM and IgG serum were assayed by enzyme-linked immunosorbent assay (ELISA). After series of bleeding the mice were challenged with 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution in the footpad on day 14. Footpad swelling was measured 24 or 48 h after the challenge. Peak responses of the anti-TNP IgM and IgG production were detected 4 or 6 days after the immunization with 10(9) TNP-SRBC. Maximum DTH response was also observed with 10(9) TNP-SRBC 24 h after the challenge on day 14. The antibody and DTH responses were also induced in other normal inbred strains such as C3H/He and DBA/1 but not BALB/c nu/nu mice. To evaluate AS-DAD in immunopharmacological studies, various immunomodulating agents were examined in BALB/c mice by subcutaneous administration on days 0, 1, 2 and 3. Cyclosporin or cyclophosphamide at 100 mg/kg/day completely inhibited not only the anti-TNP IgM and IgG production but also the TNP-specific DTH response. Prednisolone at 0.5 mg/kg/day had no significant effect on the IgM and IgG production, whereas it inhibited the TNP-specific DTH response. Interestingly, histamine-added mouse gamma-globulin at 150 MG/kg/day clearly enhanced the anti-TNP IgM and IgG production, while it showed a suppressive effect on the TNP-specific DTH response. Levamisole at 5.0 mg/KG/day showed suppressive effects on the anti-TNP IgG production without affecting the IgM production and the DTH response. These results suggest that AS-DAD is useful for evaluating the immunopharmacological action of various agents.

Animals↗

PubMed1995

Neurotropin inhibits accumulation of eosinophils induced by allergen through the suppression of sensitized T-cells.

A non-protein extract isolated from the inflamed dermis of rabbits inoculated with vaccinia virus (Neurotropin) has been clinically used in Japan as an analgesic and anti-allergic drug. To clarify its anti-allergic mechanism, the effect of Neurotropin on eosinophil accumulation induced by ragweed pollen extract or platelet-activating factor (PAF) was examined in BALB/c mice. Neurotropin inhibited the T-cell-dependent accumulation of eosinophils induced by allergen in a dose-dependent manner when administered during sensitization. However, Neurotropin was unable to inhibit the T-cell-independent accumulation of eosinophils induced by PAF. A T-cell transfer experiment was performed to address the inhibitory mechanism. A marked accumulation of eosinophils was observed when recipients were injected i.p. with allergen and Nylon wool column-passed splenic T-cells from the sensitized donor mice. However, significant accumulation of eosinophils was not observed when sensitized donor mice were administered with Neurotropin but not saline. Taken together, these results suggest that Neurotropin inhibits the accumulation of eosinophils induced by allergen via the suppression of sensitized T-cell induction, or alternatively by interfering with T-cell function.

Adjuvants, Immunologic↗

PubMed1995

Age-related differential mRNA expression of T cell cytokines in NZB/NZW F1 mice.

The mRNA expression of interleukin (IL)-2, IL-2 receptor-alpha-chain (IL-2R alpha), IL-4 and interferon-gamma (IFN-gamma) in spleen cells from NZB/NZW F1) mice following the stimulation with concanavalin A (Con A) was examined by Northern blot analysis. Kinetic patterns of the mRNA expression after the stimulation were not different between 2-month-old and 6 to 8-month-old B/W F1 mice. However, relative mRNA expression of IL-2 to a cytoskeletal protein, alpha-Tubulin was lower in 6 to 8-month-old B/W F1 mice than in 2-month-old mice. Similar but not significant tendency was observed in IL-2R mRNA expression. In contrast, Relative IL-4 mRNA expression in 6 to 8-month-old B/W F1 mice was significantly higher than that in 2-month-old animals. On the other hand, no apparent change was observed in IFN-gamma mRNA expression. Flow cytometric analysis indicated that there was no apparent difference in proportion of L3T4 positive T cells in spleen cells from 2 and 6 to 8-month-old B/W F1 mice. These results suggest that mRNA expression of IL-2 and IL-4 differentially changes with aging in autoimmune B/W F1 mice.

Age Factors↗

PubMed1995

[Inhibitory effect of histamine-added mouse gamma-globulin on eosinophil accumulation induced by allergen in BALB/c mice].

Histamine-added human gamma-globulin (HG) has been clinically used as an anti-allergic drug for asthma, allergic rhinitis and atopic dermatitis. Retrospective analysis of clinical data have indicated that s.c. administration with HG not only improves clinical symptoms but also suppresses the number of eosinophils of nasal secretion or peripheral blood in allergic patients. Thus, the possibility was explored that HG may actively suppress eosinophil accumulation in allergic inflammation. The eosinophil accumulation in peritoneal cavity was induced by i.p. injection with ragweed pollen extract in BALB/c mice which had been repeatedly sensitized with the allergen for three weeks. Histamine-added mouse gamma-globulin (Mouse HG) at 150 mg/kg/day markedly inhibited the allergen-induced eosinophil accumulation when administered s.c. two times a week for three weeks. The inhibitory effect was almost the same as that of cyclosporin A at 100 mg/kg/day. Interestingly, equivalent dose of histamine or mouse gamma-globulin alone had no inhibitory effect in the same system. These results suggest that HG suppresses chronic allergic inflammation through the inhibition of eosinophil accumulation.

Allergens↗

PubMed1995

Acidic fibroblast growth factor protects memory and immunoreactivity impairment in senescence accelerated mice.

Subcutaneous injection of aFGF once per a week into senescence accelerated mice (SAM)P8 was begun at 3 weeks after birth and continued for 10 months. Saline was injected as a control. Learning and memory and cellular immunological functions in the aFGF (F) group were enhanced significantly and while those of the saline (S) group deteriorated. The number of cholinergic neurons was decreased slightly and choline acetyltransferase activity in individual neurons in the medial septum which send monosynaptic terminals to the hippocampus was significantly decreased in the S group, but were more spared in the F group. The MAO-B activity was significantly lower in the F group than in the S group. The respective densities of muscarinic and NMDA receptors and the aFGF receptor, i.e. FGFR-1 in the hippocampus were also significantly higher in the F group than in the S group. The delayed type hypersensitivity reactions (DTH) in the footpad caused by challenge with trinitrophenyl or sheep red blood cells as measured at the end of the 2nd and 7th months, indicated the T cell immune response. Both types of DTHs were reduced in the 7th month as compared with the 2nd month in the S group. However, aFGF administration protected against this reduction in response with age. These results show that aFGF provides protection against impairment of not only learning and memory but also the DTH immunoreactivity in SAMP8, indicating thereby a close relationship between learning-memory and T cell immune function.

Aging↗

PubMed1994

Vasospasmolytic effect of KRN2391 on 3,4-diaminopyridine-induced rhythmic contraction of porcine coronary artery.

1. In the present study, we examined the vasospasmolytic effect of KRN2391 on rhythmic contractions of porcine coronary artery caused by 3,4-diaminopyridine (3,4-DAP) compared with cromakalim and nitroglycerin. 2. KRN2391 at 10(-7) showed a tendency to prolong the cycle length and at 10(-6) M completely eliminated rhythmic contractions in all preparations. The elimination by 10(-6) M KRN2391 was antagonized by either oxyhemoglobin (10(-5) M) or glibenclamide (3 x 10(-6)) although not completely. 3. Cromakalim at 10(-5) M and nitroglycerin at 10(-7) M completely eliminated 3,4-DAP-induced rythmic contractions in all preparations. The elimination by cromakalim and nitroglycerin was completely antagonized by glibenclamide and oxyhemoglobin, respectively. 4. The present study suggests that the vasospasmolytic effect of KRN2391 on 3,4-DAP-induced rhythmic contractions is based on its nitrate action and K channel opening action.

4-Aminopyridine↗

PubMed1993

Hemodynamic profile of KRN2391, a novel vasodilator, in anesthetized dogs.

In the present study, we compared the effects of KRN2391 (N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide monomethanesulfonate), a novel vasodilator, with those of nicorandil and nifedipine on hemodynamic profiles. KRN2391 (1-30 micrograms), nicorandil (10-300 micrograms), and nifedipine (0.1-3 micrograms) increased coronary, mesenteric, renal and femoral blood flows in a dose-dependent manner when intraarterially administered. KRN2391 was approximately 18 times more potent than nicorandil and about five times less potent than nifedipine in increasing coronary blood flow. Intravenous (i.v.) administration of KRN2391, nicorandil, and nifedipine produced increases in coronary and mesenteric blood flows and decreases in these vascular resistances. Although nicorandil i.v. had no significant effect on renal blood flow (RBF), nifedipine i.v. decreased RBF whereas KRN2391 i.v. increased it. Femoral BF (FBF) decreased only at the highest i.v. dose of KRN2391 and decreased after an initial increase with nicorandil. Nifedipine i.v. had no significant effect on FBF. The effects of these three agents in increasing BF and in decreasing vascular resistance were most prominent in coronary vasculature. The duration of the effect of KRN2391 in increasing coronary BF (CBF) was longer than that of nicorandil but was similar to that of nifedipine. The hypotensive effect of KRN2391 was also weaker than its effect in increasing CBF in comparison with nicorandil and nifedipine. Thus, KRN2391 was demonstrated to possess a preferential activity on coronary vasculature.

Anesthesia↗

PubMed1993

Dissimilarity in the mechanisms of action of KRN2391, nicorandil and cromakalim in canine renal artery.

In the present study, we examined the mode of action of KRN2391 (N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide monomethanesulphonate) in isolated canine renal artery compared with those of nicorandil and cromakalim. KRN2391 (10(-8)-3 x 10(-5) M), nicorandil (10(-7)-3 x 10(-4) M) and cromakalim (10(-8)-3 x 10(-5) M) relaxed renal arteries contracted by 25 mM KCl in a concentration-dependent manner. KRN2391-induced relaxation was inhibited by methylene blue (10(-5) M) and glibenclamide (10(-6) M). Nicorandil-induced relaxation was inhibited by methylene blue, but not by glibenclamide. The concentration-relaxation curve for cromakalim displayed a rightward parallel shift in the presence of glibenclamide. In the control observation, KRN2391 and nicorandil also produced full relaxation, but cromakalim did not. The present results suggest that KRN2391 acts as both a nitrate and a potassium channel opener, and nicorandil acts only as a nitrate and only in canine renal artery.

Animals↗

PubMed1993

Comparison of the effects of KRN2391 and other coronary dilators on porcine isolated coronary arteries of different sizes.

The present study was performed to determine whether KRN2391 (N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide monomethanesulphonate), a novel vasodilator, shows different effects on porcine isolated coronary arteries of different sizes. The vasodilating effects of KRN2391 on porcine large (2.5-3.0 mm outer diam.) and small (0.8-1.0 mm) coronary arteries were also compared with those of cromakalim, nicorandil, nifedipine, nitroglycerin and adenosine. The relaxant effects of these drugs were examined in coronary arteries contracted by 25 mM KCl. Nitroglycerin caused greater relaxation in large vessels than in small vessels. In contrast, adenosine, nifedipine and cromakalim caused greater relaxation in small vessels. However, there was no difference between large and small vessels in the relaxing effects of KRN2391 and nicorandil. These unique features of KRN2391 and nicorandil appear to be beneficial in ischaemic heart disease.

Adenosine↗

PubMed1993

Evidence for serum factors modulating antibody production in normal and macular mice.

The macular mutant mouse is a model of Menkes' kinky hair disease, which is characterized by a deficiency of ceruloplasmin in the serum. In hemizygotic mice (ml/y), the antibody production against sheep red blood cells (SRBC) was decreased. Treatment with normal (+/y) mouse serum increased in a dose-dependent manner the antibody response of ml/y mouse spleen cells in vitro. However, +/y mouse serum had no effect on +/y mouse spleen cells, even at high doses up to 5%. In contrast, ml/y mouse serum decreased antibody production in +/y mouse spleen cells in a dose-dependent manner. Antibody production in +/y mouse spleen cells decreased with time, after pretreatment with ml/y mouse serum. However, serum from ml/y mice injected with ceruloplasmin did not decrease antibody production in +/y mouse spleen cells but rather increased it in ml/y mouse spleen cells. Ceruloplasmin had no effect on the production of antibodies against SRBC in ml/y and +/y mouse spleen cells in vitro. These findings suggest that one or more enhancers of antibody production exist in normal mouse serum and that one or more suppressors of normal antibody production exist in ml/y mouse serum. It is proposed that the activities of these factors in serum may be regulated by ceruloplasmin.

Animals↗

PubMed1993

Mechanism of action of KRN2391, a novel vasodilator, in canine mesenteric artery.

The present study was performed to clarify the mechanism of vasodilation of KRN2391 in canine mesenteric artery compared with those of nicorandil and cromakalim. We used the responses of isolated cranial mesenteric artery in vitro and changes in mesenteric blood flow in vivo as indicators reflecting the responses of a conductive artery and resistive arterioles, respectively. In isolated cranial mesenteric artery, KRN2391 (10(-8)-10(-5) M), nicorandil (10(-7)-10(-4) M) and cromakalim (10(-7)-10(-5) M) relaxed contractions caused by 25 mM KCl in a concentration-dependent manner. The concentration-relaxation curve for KRN2391 was shifted to the right by either methylene blue (10(-5) M) or glibenclamide (10(-6) M), but the inhibitory effect of methylene blue was more potent than that of glibenclamide. The concentration-relaxation curve for nicorandil was shifted to the right by methylene blue, but not by glibenclamide. In addition, the curve for cromakalim was shifted to the right by glibenclamide, but not by methylene blue. In in vivo experiments, the injections of KRN2391 (0.3-3 micrograms/kg), nicorandil (10-100 micrograms/kg) or cromakalim (1-10 micrograms/kg) into the mesenteric artery increased mesenteric blood flow in a dose-dependent manner. Glibenclamide (5 mg/kg, i.v.) attenuated the increase in mesenteric blood flow caused by KRN2391, nicorandil and cromakalim, but had no effect on that caused by nifedipine (1 microgram/kg). The ED20 value increased about 4.7-fold for KRN2391, 3.7-fold for nicorandil and 11.5-fold for cromakalim after administration of glibenclamide, as estimated from the % change to the absolute increase in mesenteric blood flow induced by nifedipine (1 microgram/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Mechanism of action of KRN2391 in canine coronary vascular bed.

The present studies were performed to clarify the mechanism of action of KRN2391 in various sizes of canine coronary artery. We used the responses of isolated large and small coronary arteries and the changes in coronary blood flow (CBF) as indicators reflecting the responses of conductive arteries and resistive arterioles, respectively. In isolated small coronary artery, the effect of KRN2391 (10(-8)-10(-5) M) was antagonized by either methylene blue or glibenclamide. In isolated large coronary artery, the vasorelaxant effect of KRN2391 (10(-8)-10(-5) M) and nicorandil (10(-7)-10(-4) M) were antagonized by methylene blue (10(-5) M) but not by glibenclamide (10(-6) M). The relaxant effect of cromakalim was antagonized by glibenclamide but not by methylene blue in isolated large coronary artery. Intracoronary arterial injection of KRN2391, nicorandil or cromakalim produced an increase in CBF dose-dependently. Glibenclamide (5 mg/kg, i.v.) attenuated the increase in CBF caused by KRN2391, nicorandil and cromakalim. ED20, the dose that produced an increase in CBF by 20 ml/min, increased about 5-fold for KRN2391 and nicorandil and about 12-fold for cromakalim after administration of glibenclamide. These results suggest that the mechanism of action of KRN2391 and nicorandil depends on the segment of coronary arteries; i.e., they show a nitrate action alone in large coronary artery, and a K-channel opening action in addition to a nitrate action as the size of the coronary artery decreases.

Animals↗

PubMed1993

Effect of KRN2391, a novel vasodilator, on various experimental anginal models in rats.

The antianginal effect of KRN2391, N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide monomethanesulfonate, on various anginal models in rats was compared with those of nifedipine and nicorandil. Angina pectoris was induced by methacholine or isoproterenol, and the change in the ST-segments in the electrocardiogram (ECG) was used as the parameter to indicate angina pectoris. The intracoronary administration of methacholine (3 micrograms) produced an elevation in the ST-segment of the ECG. This ST-elevation was inhibited by the intravenous administration of KRN2391 (30 and 100 micrograms/kg), nifedipine (100 and 300 micrograms/kg) and nicorandil (1000 and 3000 micrograms/kg). The administration of isoproterenol (10 micrograms/kg/min, i.v.) produced a depression of the ST-segment of the ECG. The intravenous administration of KRN2391 (100 micrograms/kg), nifedipine (100 micrograms/kg) and nicorandil (3000 micrograms/kg) inhibited the ECG changes induced by isoproterenol. These results suggest that KRN2391 exerts a potent protective effect on angina pectoris models compared with nifedipine and nicorandil. KRN2391 appears to be useful as an antianginal drug.

Angina Pectoris↗