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T Ohhashi

Publications and source records attributed to T Ohhashi.

At least 19 recordsLinked to original sources
PubMed1997

Capsaicin-induced nitric-oxide-dependent relaxation in isolated dog urethra.

Capsaicin (5 x 10[-8] to 5 x 10[-5] M) produced a non-adrenergic and non-cholinergic phasic relaxation in a concentration-dependent manner in isolated dog urethral preparations precontracted by noradrenaline. The mode of action of capsaicin was investigated with special reference to the possible involvement of endogenous nitric oxide (NO). A marked tachyphylaxis was observed in the responses to capsaicin. Pretreatment with NG-nitro-L-arginine-methyl-ester (L-NAME) prevented or markedly reduced the inhibitory effect of L-NAME. Methylene blue inhibited the capsaicin-induced relaxation. In preparations stored at 4 degrees C for 72 h, the reduction in the capsaicin-induced relaxation was significantly greater than that in the relaxation induced by either electrical field stimulation or by sodium nitroprusside. We conclude that capsaicin produces an endogenous-NO-dependent relaxation in the isolated dog urethra via mechanisms that deteriorate during cold storage of the preparations.

Animals↗
PubMed1997

The primary structure of the Cl(-)-translocating ATPase, b subunit of Acetabularia acetabulum, which belongs to the F-type ATPase family.

The genes possibly encoding the b subunit (50 kDa) of the Cl(-)-translocating ATPase of Acetabularia acetabulum were cloned from total RNA and from poly(A)+ RNA and sequenced. The deduced amino acid sequence of the open reading frame consisted of 478 amino acids and showed high similarity to the beta subunit of chloroplast F1-ATPase. Gene fragments encoding the putative beta subunit of chloroplast F1- (273 bp) and mitochondrial F1-ATPases (332 bp) were also cloned from A. acetabulum and sequenced, respectively. The deduced amino acid sequence of the chloroplast F1-ATPase showed 92.5% identity to be primary structure of the b subunit of the Cl(-)-translocating ATPase, while the nucleotide sequences were 79.9% identical. The deduced amino acid sequence of the latter was 77.3% identical to that of the b subunit of the Cl(-)-translocating ATPase and the nucleotide sequences were 67.5% identical. By Northern analysis, these three beta-like genes were demonstrated to be transcribed with different sizes of RNA species. A putative chloroplast F1-beta fragment also hybridized with chloroplast DNA isolated from the organism.

Acetabularia↗
PubMed1997

Inhibitory effects of fluorescein isothiocyanate photoactivation on lymphatic pump activity.

The effects of photoactivation of fluorescein 5'-isothiocyanate (FITC)-dextran on lymphatic pump activity of rat mesenteric collecting vessel were studied in vivo. Rats were anesthetized with intraperitoneal alpha-chloralose and urethane, and the mesenteries were studied by using intravital videomicroscopic techniques. The diameter of the collecting lymph vessels were continuously monitored and lymphatic pump parameters (end diastolic diameter, end systolic diameter, stroke volume index, ejection fraction, contraction frequency, and pump flow index) were calculated. FITC-dextran (42 nmol/100 g body wt) without illumination caused no disturbance of lymphatic pump activity. Photoactivated FITC-dextran significantly increased end systolic diameter and decreased stroke volume index, ejection fraction, contraction frequency, and pump flow index. End diastolic diameter was not changed throughout the experiment. Superoxide dismutase (120 U/ml) and catalase (5000 U/ml) had no protective effect on photoactivated FITC-induced pump dysfunction, while histidine (singlet oxygen quencher, 10 mM) significantly prevented the disturbance of pump parameters. These results indicate that photoactivation of FITC induces negative chronotropic and negative inotropic effects in lymphatic pump activity through generation of singlet oxygen in the mesentery.

Animals↗
PubMed1997

Instrumentation of a handy microscopic probe for concurrent observation and measurement of active sweat secretion, and its applications.

Instrumentation for the concurrent, dynamic monitoring of active sweat glands and perspiration volume is described. A device for the measurement of the rate of sweat secretion was installed on the head part of a microscope. The combined apparatus (microscopic probe) is handy for use and its weight is very light (ca. 300 g). The microscopic probe is easily attached to the surface of human skin. The dynamic activities of the sweat glands on the forehead and nose and under the nose were observed and measurement when thermal, mental and physical stimuli were applied. The activities of individuals sweat glands were asynchronous when observed in units of a few seconds or less; however, they worked synchronously in a unit period of several seconds. The latter were recorded as fine peaks by a strip chart recorder. The proposed system may be useful for the study of the sympathetic nervous system, the skin sympathetic reflex and the working of sudomotor nerves.

Adult↗
PubMed1997

Flow- and agonist-mediated nitric oxide- and prostaglandin-dependent dilation in spinal arteries.

Isolated rabbit spinal resistance-sized arteries (approximately 100 microns in diameter and approximately 3 mm long) were cannulated at both ends with glass micropipettes and perfused at constant pressure (60 mmHg). An increase of flow rate corresponding to a change of pressure gradient (delta P) ranging from 0 to 20 mmHg produced a flow-dependent vasodilation. Treatment with 50 microM aspirin or 10 microM indomethacin produced a significant reduction of the flow-dependent vasodilation only at delta P of 5 mmHg. In contrast, treatment with N omega-nitro-L-arginine methyl ester (L-NAME, 30 microM) produced no significant change. In the presence of 10 microM indomethacin, however, 30 microM L-NAME caused a marked decrease in the arterial diameter at delta P of 5 mmHg, which was completely reversed with additional administration of 1 mM L-arginine. Acetylcholine (ACh) produced a dose-dependent increase in the arterial diameter. The ACh-induced vasodilation was significantly reduced by 10 microM indomethacin or 50 microM aspirin and partially suppressed by 30 microM L-NAME. Pretreatment with both indomethacin and L-NAME completely reduced the ACh-induced vasodilation. In the presence of 10 microM indomethacin, additional treatment with 1 mM L-arginine significantly reversed the L-NAME-induced inhibition of the ACh-mediated vasodilation. Endothelial removal with Triton X-100 significantly reduced the ACh-induced vasodilation. Isocarbacyclin (a stable prostaglandin I2 analogue), prostaglandin E2, and arachidonic acid caused a dose-dependent dilation in the small arteries. These findings suggest that prostanoids play a major role in the flow- or ACh-induced vasodilation in the rabbit spinal resistance-sized small arteries.

Acetylcholine↗
PubMed1997

[A new helical CT approach with ECG gated reconstruction].

We proposed a new helical CT approach with ECG-gated reconstruction for obtaining high quality 2D, 3D, and 4D images. Original helical images were acquired with a single helical scan with overlapping reconstruction and ECG information. Post-processing to improve temporal resolution and 4D volume set reconstruction were performed, and 2D, 3D and 4D displays were obtained. Using this new method, 2D and 3D images without cardiac motion artifacts were obtained by selecting images in diastolic phase. 2D images with cardiac motion were obtained using images of the same position and different cardiac phases. Finally, 4D images (3D images with phase information) were obtained.

Artifacts↗
PubMed1997

5-Hydroxytryptamine-induced endothelium-dependent and -independent relaxations in isolated dog anterior spinal small arteries.

The mode of action of 5-hydroxytryptamine (5HT) was investigated in isolated dog anterior spinal small arteries. Lower concentrations of 5HT (10(-9)-10(-7) M) caused a dose-dependent contraction and higher concentrations (10(-6)-10(-3) M) produced a dose-dependent relaxation of the arteries precontracted by 10(-7) M U 46619. The 5HT-induced relaxation was significantly antagonized by methiothepin (10(-9)-10(-6) M). Ketanserin (10(-6) M) and ICS 205-930 (3 x 10(-6) M) did not affect the 5HT-induced relaxation of the arteries. The relaxant response to 5HT was reduced significantly by mechanical rubbing of the endothelial cells. The 5HT-induced endothelium-independent relaxation was also antagonized significantly by methiothepin (10(-6) M). Aspirin (5 x 10(-5) M) or N omega-nitro-L-arginine methyl ester (L-NAME) (10(-6) M) significantly suppressed the 5HT-induced endothelium-dependent relaxation. L-Arginine (10(-3) M) also significantly reversed the L-NAME induced reduction of the 5HT-induced endothelium-dependent relaxation. Treatment with L-NAME in the presence of aspirin also produced much greater reduction of the 5HT-induced endothelium-dependent relaxation. Isocarbacyclin (10(-9)-10(-5) M) induced a concentration-dependent relaxation of the isolated spinal small arteries precontracted by 10(-7) M U 46619. These results suggest that 5HT induces endothelium-dependent and -independent relaxations of the isolated anterior spinal small arteries mainly via activation of 5HT1-like receptor and that endogenous nitric oxide and vasodilative prostaglandins may contribute to the 5HT-induced endothelium-dependent relaxation of the arteries.

Animals↗
PubMed1997

Macrophage-induced nitric oxide and prostanoid dependent relaxation of arterial smooth muscles.

We have studied mechanisms of vasodilation induced by supernatant fluid of rat macrophages (Mø), using an arterial bioassay preparation. The cells emigrated by an intraperitoneal injection of thioglycollate were isolated and cultured for 12 h in RPMI 1640 medium with and without 2.0 mM L-arginine. More than 98% of the isolated cells clearly demonstrated Wright's esterase staining and phagocytosis of acetylated low-density lipoprotein. The bioassay preparation was made of dog isolated femoral arteries with and without the endothelium. The supernatant of macrophages cultured in the L-arginine-free RPMI 1640 caused a significant reduction of the precontraction in the bioassay rings, being approximately 51.6-66.7% of sodium nitroprusside (SNP) induced maximum vasodilation in each ring. The supernatant of macrophages cultured in the RPMI 1640 containing 2.0 mM L-arginine produced a significantly smaller relaxation (approximately 32.3-33.3%). The Mø-induced vasodilation was significantly inhibited by the coculture of the macrophages with 1 microM dexamethasone, 10 microM cycloheximide, 50 microM N omega-nitro-L-arginine methyl ester (L-NAME), 10 microM indomethacin, or 10 microM aspirin. The L-NAME-induced inhibition was significantly reversed by an additional treatment with 100 microM L-arginine. The coculture with both L-NAME and indomethacin caused a reduction of the Mø-induced vasodilation (approximately 12.5-13.4%) similar to reductions produced by dexamethasone (approximately 10.8-12.1%) and cycloheximide (approximately 11.4-12.4%). Coculture with 10 micrograms/mL bacterial lipopolysaccharide caused a slight facilitation of the Mø-induced vasodilation (approximately 78.2-79.6%). These findings suggest that supernatant fluid of rat exuded macrophages cultured with low concentrations of L-arginine causes an endogenous nitric oxide (NO) and vasodilative prostaglandin dependent relaxation of arterial smooth muscles.

Animals↗
PubMed1996

Acetylcholine- and flow-induced production and release of nitric oxide in arterial and venous endothelial cells.

To study flow-mediated responses in a conduit vein, we investigated the physiological characteristics of endothelium-dependent acetylcholine (ACh)- and flow-induced relaxations using a conventional bioassay cascade. Cylindrical segments isolated from canine common carotid arteries and external jugular veins were perfused at a constant mean flow rate ranging from 1 to 8 ml/min. Endothelium-derived nitric oxide (NO) activity in perfusion effluent through the arterial and venous segments was measured by relaxation of endothelium-denuded arterial rings and arterial and/or venous rings precontracted by prostaglandin F2 alpha, respectively. Stimulation by a flow rate of 8 ml/min on the arterial and venous endothelial cells produced approximately 60 and 20% of the maximum relaxation in the arterial and venous rings, respectively. ACh (10(-6) and 10(-5) M) perfused through the arterial and venous segments with endothelium caused dose-related relaxations of both bioassay rings. The ACh- and flow-induced relaxations were completely reduced by mechanical removal of the endothelial cells. Pretreatment with 5 x 10(-5) M NG-nitro-L-arginine methyl ester (L-NAME) produced a significant reduction of the ACh- and flow-induced vasodilation. Additional treatment with 10(-4) M L-arginine significantly reversed the L-NAME-induced inhibition of ACh-induced relaxation but had no effect on flow-induced relaxation. When the flow rate was increased from 2 to 4 ml/min, the same concentrations of ACh produced larger dose-related relaxations than those obtained at a flow rate of 2 ml/min. Pretreatment with 25 U/ml superoxide dismutase caused no significant effect on the flow-mediated potentiation of ACh-induced relaxation. These findings suggest that venous endothelial cells of canine large vein are able to produce and release NO by stimulation of increased flow or ACh to a significantly lesser extent compared with the artery and that ACh-induced vasodilation is potentiated by an increase in shear stress up to approximately 4 dyn/cm2 loaded on the endothelial cells.

Acetylcholine↗
PubMed1995

5-Hydroxytryptamine-induced NO-dependent relaxation in isolated strips of monkey popliteal lymph nodes.

5-Hydroxytryptamine (5-HT, 0.01-100 microM) and 5-carboxamidotryptamine (5-CT, 0.001-10 microM) produced dose-related relaxations in strips cut from monkey popliteal lymph nodes precontracted with a perfusion of Krebs bicarbonate solution containing 80 mM KCl. These 5-HT agonists caused no significant effect on the basal tone of the lymph node strips. The 5-HT-induced relaxation is competitively antagonized by pretreatment with a selective 5-HT1-like receptor antagonist, methiothepin (0.01-0.1 microM). Schild plot analysis showed that the pA2 value and slope of methiothepin against 5-HT were 8.80 +/- 0.11 and 0.99 +/- 0.07 (n = 6), respectively. Pretreatment with methysergide (0.01-0.1 microM) significantly attenuated the 5-HT-induced relaxation of the strips. On the other hand, treatment with ketanserin (0.01-0.1 microM) and ICS-205-930 (0.01-0.1 microM) caused no significant effect on the 5-HT-or the 5-CT-induced relaxation. The 5-HT-induced relaxation was significantly reduced by 10 microM NG-monomethyl-L-arginine, which was reversed by 1 mM L-arginine. The relaxation in the lymph node strips was also significantly reduced by treatment with 10 microM methylene blue but not with 30 microM aspirin. These results suggest that 5-HT1-like receptors exist in the monkey popliteal lymph nodes. Stimulation of these receptors produces an endogenous nitric oxide (NO)-dependent relaxation in lymph node smooth muscle through an activation of cytosolic guanylate cyclase in the cells.

Animals↗
PubMed1995

Histopathological features of atrophic thyroiditis with blocking type-TSH binding inhibitor immunoglobulins.

To investigate the histopathological features of atrophic thyroiditis (AT) with blocking type-TSH binding inhibitor immunoglobulins (TBII), the present morphological observations were carried out employing additional immunohistochemical procedures. Moreover, these were compared with examples of goitrous Hashimoto's thyroiditis showing negative TBII (HT). There exist apparent differences between AT and HT. In particular, significant follicular atrophy with epithelial flattening including decreased positive staining of the follicular epithelial cells for thyroglobulin in AT was characteristically observed. These results suggest that the mechanism for the development of hypothyroidism in AT with blocking type-TBII might be due to suppression of thyroid cell function through the inhibition of endogenous TSH stimulation by the blocking antibody with subsequent epithelial degenerative destruction.

Adult↗
PubMed1995

Histamine H2 receptor-mediated endothelium-dependent relaxation in canine spinal artery.

The mechanisms of histamine-induced relaxation were investigated in isolated canine spinal branches of intercostal artery (SBICA). Histamine (10(-7) to 10(-4)M) and dimaprit (3 x 10(-6) to 3 x 10(-4)M) produced concentration-dependent relaxation in the SBICA which had been contracted by 5 x 10(-6)M norepinephrine, whereas 2-pyridylethylamine caused only a very small relaxation. The histamine- and dimaprit-induced relaxation were inhibited by famotidine but not by diphenhydramine. In the SBICA without endothelium, histamine elicited very little relaxation. Aspirin (5 x 10(-5)M) and AA 861 (10(-5)M) did not affect the histamine-induced relaxation. Treatment with L-NMMA (3 x 10(-5)M) or methylene blue (10(-5)M) significantly suppressed the acetylcholine-induced relaxation of the SBICA but not the histamine-induced one. These results suggest that histamine produces relaxation in the isolated canine SBICA through stimulation of H2-receptors on the endothelium. The relaxing mediator(s) released by histamine seems to be neither endogenous prostaglandins, lipoxygenase products, nor nitric oxide.

Animals↗
PubMed1994

Effects of isocarbacyclin, a stable prostacyclin analogue, on monkey isolated cerebral and peripheral arteries.

1. The effects of isocarbacyclin (TEI 7165), a stable prostacyclin analogue, were examined in monkey isolated cerebral and peripheral arteries. 2. Addition of TEI 7165 (0.1 nM-10 microM) produced a dose-dependent relaxation in cerebral arteries pre-contracted with 1 microM 5-hydroxytryptamine (5-HT). High concentrations (more than 1 microM) of TEI 7165 elicited a transient contraction followed by a sustained relaxation. 3. TEI 7165 also elicited a dose-dependent relaxation in the peripheral (except popliteal) arteries. The maximum relaxation induced by 10 microM TEI 7165 was greater (P < 0.05) in the mesenteric artery than in the cerebral artery. The negative logarithm of the EC50 value for the mesenteric, 7.6 +/- 0.3, was greater (P < 0.05) than that for the cerebral artery, 6.4 +/- 0.3. The decreasing order of potency for the TEI 7165-induced relaxation was as follows: mesenteric > renal > cerebral > coronary > popliteal. 4. Removal of the endothelium did not significantly affect TEI 7165-induced relaxations. 5. The transient contraction produced by high concentrations of TEI 7165 was not observed in cerebral arteries precontracted with 1 nM U46619, a stable analogue of thromboxane A2 (TXA2). Furthermore, the TEI 7165-induced contraction was markedly suppressed (P < 0.05) by treatment with 10 nM S1452, a TXA2 blocking agent. 6. These results suggest that TEI 7165 causes an endothelium-independent relaxation in monkey cerebral and peripheral arteries, and that there is a marked regional difference in the TEI 7165-induced relaxations. A high concentration of TEI 7165 also produces a transient contraction which is probably through activation of TXA2 (TP-) receptors.

Animals↗
PubMed1994

Purification and characterization of a membrane-bound ATPase from Acetabularia cliftonii that corresponds to a Cl(-)-translocating ATPase in Acetabularia acetabulum.

A Mg(2+)-ATPase was solubilized from membranes of Acetabularia cliftonii using nonanoyl-N-methylgluconamide and purified by ion-exchange and gel permeation chromatography. One active ATPase fraction after Mono Q chromatography had a specific activity of 10 units/mg of protein. Judged from subunit composition [54 (a), 50 (b) with a fainter band around 40 kDa], catalytic properties, and N-terminal amino acid sequence of the b subunit, the isolated enzyme was comparable to the Cl(-)-ATPase of Acetabularia acetabulum. Immunological characterization of both subunits showed significant similarity to the F type of ATPase. Cl(-)-transport activity was observed by reconstitution studies into liposomes.

Acetabularia↗
PubMed1994

Chloroplast ATPase in Acetabularia acetabulum: purification and characterization of chloroplast F1-ATPase.

ATPases were isolated from chloroplasts of the unicellular marine alga Acetabularia acetabulum. Two preparations of ATPase, a chloroplast-enriched fraction and an alpha beta gamma-complex were compared. The alpha beta gamma-complex was released into an EDTA solution and purified by anion-exchange chromatography, hydrophobic chromatography, and gel permeation chromatography. The subunit composition of this enzyme appeared to be 52-53 (alpha), 51 (beta), and 40 (gamma) kDa from SDS-PAGE. ATPase activity was enriched about 260-fold to a specific activity of approximate 4.1 U.mg protein-1. The catalytic properties of the alpha beta gamma-complex were as follows: pH optimum at 7.5; substrate specificity, ATP > ITP, GTP > UTP = CTP (Km for ATP 0.2 mM); divalent cation requirement, Mg2+ = Mn2+ = Co2+ > Zn2+ > Ni2+ > Ca2+; ATPase activity was inhibited by monovalent anions (NO3-, SCN-), while monovalent cations had neither inhibitory nor stimulatory effect. Orthovanadate had no inhibitory effect on the enzyme activity of alpha beta gamma-complex. Azide was the most effective inhibitor of the alpha beta gamma-complex. N-Terminal amino acid sequences of the alpha and beta subunits were not obtained and appeared to be blocked. The gamma subunit gave a sequence of AGLKEMKD-XIGSVXNTKKI, which showed 60% similarity to the gamma subunits of spinach and Chlamydomonas reinhardtii CF1-ATPase and EF1-ATPase.

Acetabularia↗
PubMed1994

5-Hydroxytryptamine-2 and -4 receptors located on bovine isolated mesenteric lymphatics.

Effects of 5-hydroxytryptamine (5-HT) agonists were investigated in the bovine isolated mesenteric lymphatics, and then the 5-HT receptor subtypes in the responses were pharmacologically classified by use of several 5-HT antagonists. Addition of 5-HT and that of alpha-methyl-5-hydroxytryptamine (alpha-methyl-5-HT) both produced concentration-dependent contractions in the presence of 3 x 10(-6) M [(1 alpha H, 5 alpha H)-8-methyl-8-azabicyclo(3.2.1)oct-3 alpha-yl]1H-indole-3-carboxylate hydrochloride, whereas 5-carboxamidotryptamine (5-CT) and 2-methyl-5-hydroxytryptamine (2-methyl-5-HT) caused no, or only slight, contraction in the lymphatics. Pretreatment with ketanserin caused a significant shift to the right in the concentration-response curve for 5-HT or alpha-methyl-5-hydroxytryptamine. Schild plot analyses showed that the pA2 values for ketanserin against 5-HT and alpha-methyl-5-hydroxytryptamine were 8.75 and 8.68, respectively. In contrast, 5-CT, 5-HT and metoclopramide caused concentration-dependent relaxations in the presence of 10(-6) M ketanserin in the lymph vessels after contraction with prostaglandin F2 alpha. 2-Methyl-5-HT up to 10(-4) M did not produce any relaxation. High concentrations of [(1 alpha H, 5 alpha H)-8-methyl-8-azabicyclo(3.2.1)oct-3 alpha-y1]1H-indole-3-carboxylate hydrochloride induced a significant inhibition of the 5-CT- and 5-HT-induced relaxation, but methiothepin and methysergide up to 10(-6) M and mechanical rubbing of the endothelium had no significant effect on the relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effects of vasoactive substances on the pig isolated hepatic lymph vessels.

The present study examined the responses of isolated pig hepatic lymph vessels to vasoactive substances, the classification of alpha adrenoceptors and the mode of action of acetylcholine (ACh) with special reference to the lymphatic endothelial cells. Contractions of the hepatic lymph vessels were induced by norepinephrine (NE), epinephrine, prostaglandin F2 alpha, histamine and 5-hydroxytryptamine in a dose-dependent manner. NE was the most potent vasoconstrictor agent. 5-bromo-6[2-imidazolin-2-ylamino]-quinoxaline, xylazine and clonidine also produced dose-dependent contractions. NE-induced contractions were inhibited significantly by yohimbine (10(-8)-10(-6) M) but not by prazosin (10(-8)-10(-6) M). Pretreatment with yohimbine (10(-8)-10(-7) M) or rauwolscine (10(-8)-10(-7) M) caused a parallel shift to the right of the dose-response curve for 5-bromo-6[2-imidazolin-2-ylamino]-quinoxaline. These results suggest that the NE-induced contraction in pig hepatic lymph vessels seems to be mediated mainly through stimulation of alpha-2 adrenoceptors. ACh, isoproterenol, histamine, 5-hydroxytryptamine, ATP and adenosine caused dose-dependent relaxations in the hepatic lymph vessels precontracted by 5 x 10(-6) M prostaglandin F2 alpha. ACh was the most potent vasorelaxant agent. Pretreatment with atropine (10(-9)-10(-7) M) inhibited the ACh-induced relaxation in a competitive manner. Removal of endothelium caused a significant reduction of the ACh-induced relaxation. The ACh-induced relaxation was suppressed by pretreatment with N omega-nitro-L-arginine methyl ester (3 x 10(-5) M) and methylene blue (10(-5) M) but was unaffected by aspirin (10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗