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T Ohhashi

Publications and source records attributed to T Ohhashi.

At least 55 records · Page 3Linked to original sources
PubMed1992

Improvement of reconstitution of the Cl(-)-translocating ATPase isolated from Acetabularia acetabulum into liposomes and several anion pump characteristics.

The improved reconstitution of the Mono Q-III fraction, a Cl(-)-translocating ATPase, isolated from Acetabularia acetabulum (Ikeda et al. (1990) Biochemistry 29, 2057-2065) into liposomes rendered transport properties of this enzyme clear. The liposomes were prepared by the reversed-phase method using egg lecithin and cholesterol in a molar ratio of 2:1 and the purified ATPase was incorporated into the liposomes by a dialysis for 3 h. About 80% of the ATPase was incorporated into the liposomes. The weight ratio of the enzyme to lipid was 1:400-600. A sigmoid curve was obtained when the Cl(-)-transport activity of the enzyme was plotted against Cl- concentration. Hill's plot afforded a half-substrate concentration [S]0.5 of 45 mM and a Hill's coefficient n of 2.33. Effects of Br- and F- on the Cl(-)-transport were also examined in the reconstituted system, both halide ions decreased the 36Cl- efflux significantly. These kinetic data are in good agreement with the electrophysiological data presented by Tittor et al. ((1983) J. Membr. Biol. 75, 129-139).

Acetabularia↗
PubMed1992

Effects of aortic pressure and vasoactive agents on the vascular resistance of the vasa vasorum in canine isolated thoracic aorta.

1. We have developed a new preparation for continuously measuring changes in vascular resistance of the vasa vasorum of the canine isolated thoracic aorta perfused at a constant flow rate with Krebs-bicarbonate solution. 2. An increase of more than 150 mmHg in aortic pressure caused a significant increase in the vascular resistance of the vasa vasorum. 3. 5-Hydroxytryptamine (5-HT), noradrenaline (NA), adrenaline and dopamine caused dose-dependent increases in the vascular resistance of the vasa vasorum. The decreasing order of potency in the vasoconstrictor responses was as follows: 5-HT >> NA = adrenaline >> dopamine. The 5-HT- and adrenaline-induced vasoconstrictor responses were inhibited by methysergide and by phentolamine plus propranolol, respectively. 4. Acetylcholine (ACh), isoprenaline (ISP), histamine (His), ATP, ADP and adenosine produced dose-related decreases in the vascular resistance of aortic vasa vasorum perfused with the Krebs solution containing 10(-5) M-NA. The decreasing order of potency in the response was as follows: ACh = ISP > His >> adenosine = ATP = ADP. The ACh-, ISP- and His-induced vasodilator responses were antagonized by atropine, propranolol and famotidine, respectively. 5. The results suggest that the preparation described is useful for studying the regulation of vascular resistance of aortic vasa vasorum and that aortic pressure and vasoactive compounds may directly regulate the vascular resistance of the vasa vasorum in canine isolated thoracic aorta.

Animals↗
PubMed1992

Interstitial nephritis associated with glomerulonephritis in a patient with Hashimoto's disease and idiopathic portal hypertension.

A middle-aged women with hypothyroidism, idiopathic portal hypertension and nephrotic syndrome is presented. This unusual clinical appearance could not be explained as SLE by serological examinations. Pathohistological examinations showed "Banti's liver", Hashimoto's thyroiditis and diffuse proliferative glomerulonephritis with severe tubulo-interstitial nephritis. Immunohistochemical studies revealed IgA deposits in glomeruli. Electron microscopic study disclosed peculiar lucent areas of rarefaction with osmiophilic particles in tubular basement membranes. This tubulointerstitial nephritis was considered to be related to the immunological mechanism involving thyroid gland, liver and kidney disorders. This case thus had a clinically rare combination of these three.

Female↗
PubMed1991

Preparative high-yield electroelution of proteins after separation by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and its application to analysis of amino acid sequences and to raise antibodies.

A method for the preparative high-yield electroelution of proteins from sodium dodecyl sulphate (SDS) polyacrylamide gel strips was established. The method consisted of SDS-polyacrylamide gel electrophoresis, detection of proteins with sodium acetate and electrophoretic elution at 200 V for 3 h by utilizing a horizontal flat-bed gel electrophoresis apparatus. Standard proteins with molecular masses of 14-66 kilodalton (cytochrome c, aldolase, ovalbumin and bovine serum albumin) were recovered with an average yield of 73.6 +/- 2.3%. A membrane-bound protein, rat skeletal muscle Ca(2+)-ATPase (100 kilodalton) was also well recovered (over 60%). This method was applicable to the purification of proteins required for N-terminal amino acid sequencing and to raise antibodies.

Amino Acid Sequence↗
PubMed1991

Time-dependent potentiation of contractile response to norepinephrine in canine isolated cerebral arteries.

The time course of contractile responses to alpha-adrenoceptor agonists was investigated using various arteries isolated from dogs and monkeys. The contractile response to norepinephrine was increased during the time course of the experiment in canine basilar and internal carotid arteries, whereas the response of isolated canine external carotid arteries and monkey internal carotid arteries did not change significantly. Treatment with 10(-7) M propranolol, 5 x 10(-6) M cocaine plus 10(-5) M hydrocortisone, or 5 x 10(-5) M acetylsalicylic acid did not significantly affect the time-dependent potentiation of the norepinephrine-induced contraction in canine internal carotid arteries. The time-dependent enhancement in the response to norepinephrine was also observed in the arterial preparations from which the endothelial cells were removed. The contractile response of canine internal carotid arteries to phenylephrine did not alter significantly throughout the experiments. On the other hand, the responses to clonidine and xylazine were markedly enhanced with time. Significant potentiation of the norepinephrine-induced contraction was observed in canine internal carotid arteries treated with 10(-8) M prazosin, whereas 10(-8) M yohimbine attenuated the time-dependent potentiation. These results suggest that the contractile responses of isolated canine basilar and internal carotid arteries to norepinephrine are potentiated during the course of the experiment, which is likely to be related, in part, to an enhancement in alpha 2-adrenoceptor mediated contraction.

Animals↗
PubMed1991

Acetylcholine-induced release of endothelium-derived relaxing factor from lymphatic endothelial cells.

Ring segments of dog thoracic ducts precontracted with a high concentration of norepinephrine (NE) relaxed in a concentration-dependent manner in response to acetylcholine (ACh) or sodium nitroprusside (SNP). Pretreatment with atropine inhibited the ACh-induced relaxation in a competitive manner. The Schild plot showed a slope of 1.1 +/- 0.2 and a pA2 value of 10.4 +/- 0.4 (n = 6 ring segments). Removal of endothelium caused a complete inhibition of the ACh-induced relaxations in precontracted dog thoracic ducts. ACh, which failed to relax precontraction of the ring segment when mounted separately, induced relaxation in the same preparation when it was mounted as a "sandwich" with the longitudinal strip. The ACh-induced relaxations in the lymphatic preparations with endothelium were suppressed or abolished by pretreatment with oxyhemoglobin (10(-6) and 10(-5) M), methylene blue (10(-6) and 10(-5) M), and NG-monomethyl-L-arginine (3 x 10(-5) M), but the relaxations were unaffected by aspirin (10(-5) M). Pretreatment with methylene blue (10(-5) M) also caused a significant reduction of the SNP-induced relaxations in the precontracted thoracic ducts. It may be concluded that ACh-induced relaxation in dog thoracic ducts precontracted with NE is mediated by high-affinity muscarinic receptors in the lymphatic endothelial cells. Also, stimulation of the endothelial muscarinic receptors liberates a transferable endothelium-derived relaxing factor, which results in the relaxation of the lymphatic smooth muscles via the accumulation of cellular guanosine 3',5'-cyclic monophosphate.

Acetylcholine↗
PubMed1991

Prostaglandin F2 alpha-induced endothelium-dependent relaxation in isolated monkey cerebral arteries.

Effects of prostaglandin F2 alpha (PGF2 alpha) on isolated monkey and dog cerebral arteries were investigated to reevaluate PGF2 alpha's possible action on the endothelium. Low concentrations of PGF2 alpha ranging from 10(-11) to 10(-8) M produced a dose-dependent relaxation in the monkey arteries. PGF2 alpha (10(-7) M) produced a transient contraction followed by a small relaxation, whereas higher concentrations (greater than 10(-6) M) of PGF2 alpha induced only contractions. The PGF2 alpha-induced relaxation was not observed in the canine cerebral arteries. The PGF2 alpha-induced relaxation of the monkey cerebral arteries was not affected by treatment with 10(-7) M propranolol, 10(-7) M atropine, or 10(-6) M cimetidine. In monkey cerebral arteries without endothelium, PGF2 alpha in concentrations ranging from 10(-11) to 10(-6) M caused no relaxation. Treatment with 5 X 10(-5) M aspirin, 3 X 10(-5) M NG-monomethyl-L-arginine, and 10(-5) M oxyhemoglobin significantly suppressed the PGF2 alpha-induced relaxation. These results suggest that low concentrations of PGF2 alpha may produce an endothelium-dependent relaxation in monkey cerebral arteries and that the relaxation may be mediated by release of both endogenous vasodilative prostaglandins and endothelium-derived relaxing factor from endothelial cells.

Animals↗
PubMed1991

Beta-1 and beta-2 adrenoceptors mediate smooth muscle relaxation in bovine isolated mesenteric lymphatics.

The relaxant effects of beta adrenoceptor agonists were investigated in isolated bovine mesenteric lymphatics which had been contracted by 5-hydroxytryptamine. Addition of isoproterenol (a nonselective beta agonist), denopamine (a selective beta-1 agonist) and procaterol (a selective beta-2 agonist) caused concentration-dependent relaxations in the lymphatic preparations. There was no significant difference in the relaxant responses to the beta adrenoceptor agonists between the preparations with and without endothelium. Treatment with 10(-7) to 3 x 10(-6) M metoprolol (a selective beta-1 antagonist) shifted the concentration-response curve for denopamine to the right, whereas 10(-9) to 3 x 10(-8) M ICI 118,551 (a selective beta-2 antagonist) did not affect the relaxant response to denopamine. The relaxations of bovine mesenteric lymphatics induced by isoproterenol were suppressed by both metoprolol and ICI 118,551. The procaterol-induced relaxations were inhibited by 10(-9) to 3 x 10(-8) M ICI 118,551 but not by 10(-7) to 3 x 10(-6) M metoprolol. Schild plot analyses showed that the slope and pA2 values for metoprolol against denopamine were 1.10 and 7.59, respectively, and that those for ICI 118,551 against procaterol were 0.91 and 9.96. These results suggest that both beta-1 and beta-2 adrenoceptors are located on the smooth muscle cells in bovine mesenteric lymphatics and that stimulation of either receptor produces a marked relaxation.

Adrenergic beta-Agonists↗
PubMed1990

Characterization of prolidase I and II from erythrocytes of a control, a patient with prolidase deficiency and her mother.

Prolidase I (EC 3.4.13.9) was purified to homogeneity from the erythrocytes of a normal human (control) and the patient's mother, and prolidase II from erythrocytes of a control and the patient's mother, and prolidase from the patient's erythrocytes was also highly purified. The various properties of the patient's prolidase were compared to those of prolidase from a control and the patient's mother. Prolidase I from a control and the patient's mother had a molecular weight of about 112,000, and was composed of two subunits with an identical molecular weight of 56,000. The Km values for Gly-Pro of the control's and the patient's mother's prolidase I were 2.90 +/- 0.22 and 2.88 +/- 0.27 mM, but the Vmax values for Gly-Pro of the mother's enzyme was reduced about 30% compared to that of control enzymes (mother: 6.02 units/mg protein, control: 22.21 units/mg protein). Isoionic points of these enzymes by chromatofocusing were pH 4.6 approximately 4.7. Prolidase II from the control and the patient's mother, and the patient's prolidase had a molecular weight of about 185,000, and was composed of two subunits with an identical molecular weight of 95,000. The Km and Vmax values for various substrates of prolidase II from a control and the patient's mother, and the patient's prolidase were almost the same.

Chromatography, Gel↗
PubMed1990

Demonstration of both beta 1- and beta 2-adrenoceptors mediating negative chronotropic effects on spontaneous activity in isolated bovine mesenteric lymphatics.

The pharmacological classification of beta-adrenoceptor subtypes in isolated bovine mesenteric lymphatics was studied by using various beta-adrenoceptor agonists and antagonists. Isoproterenol (ISP) (10(-10)-10(-8) M) produced dose-dependent negative chronotropic effects on the rhythm of spontaneous contractions in the lymphatic preparation. The ISP-induced effects were dose-dependently blocked by pretreatment with 10(-8)-10(-7) M metoprolol (a selective beta 1 antagonist) as well as 10(-8)-10(-7) M propranolol (a beta 1 and beta 2 antagonist). Dobutamine (a selective beta 1 agonist) caused a dose-dependent negative chronotropic effect, which was significantly blocked by pretreatment with 10(-8) M metoprolol. Salbutamol and procaterol (selective beta 2 agonists) also produced dose-dependent negative chronotropic effects, which were dose-dependently inhibited by pretreatment with 10(-8)-10(-7) M propranolol, but not by 10(-7) M metoprolol. The decreasing order of the relative potency was as follows: ISP greater than procaterol greater than salbutamol greater than dobutamine. These results suggest that bovine mesenteric lymphatics contain both beta 1- and beta 2-adrenoceptors and that both subtypes can produce a negative chronotropic effect on the rhythm of spontaneous contractions, when stimulated.

Adrenergic beta-Agonists↗
PubMed1990

Characterization of fibroblast-derived prolidase. The presence of two forms of prolidase.

Crude enzyme solutions of prolidase were extracted from cultured human skin fibroblasts derived from control and prolidase-deficient sisters. Two forms of prolidases (prolidase-I and II) were partially purified by high performance liquid chromatography equipped with an ion exchange column. On gel filtration, the relative molecular weights of prolidase-I and II were estimated to be MW = 105,000 and 151,000, respectively. The substrate specificity of partially purified prolidase-I and II in control fibroblasts was estimated against Gly-Pro, Ala-Pro, Met-Pro. Each form of prolidase differed in its substrate specificity. In prolidase-deficient sisters, the elder with typical clinical manifestations and the younger with only slight clinical manifestations, the activity of prolidase-I was absent. However, the activity of prolidase-II was sufficiently present in both sisters. The substrate specificity of prolidase-II in the patients was similar to that of control. No difference in substrate specificity was found between these two patients.

Adolescent↗
PubMed1990

Contractile and relaxant responses of the canine isolated spinal artery to vasoactive substances.

1. Effects of vasoactive substances were investigated in the canine isolated spinal branch of the intercostal artery (SBICA). 2. Addition of angiotensin II (AII), vasopressin, noradrenaline (NA), adrenaline, 5-hydroxytryptamine (5-HT), and dopamine each produced concentration-dependent contraction in the SBICA, whereas prostaglandin F2 alpha, histamine, and tyramine caused only slight contraction. The decreasing order of the potency of contractile agents was AII much greater than vasopressin = NA greater than 5-HT greater than adrenaline much greater than dopamine. 3. Although the pD2 value for phenylephrine (5.31 +/- 0.36) was smaller than that for NA (6.48 +/- 0.13), there was no significant difference in Emax value between these two agonists in the SBICA. On the other hand, xylazine produced only a slight contraction, the pD2 value being 3.59 +/- 0.08. Phentolamine (10(-8)-10(-6) M) and prazosin (10(-8)-10(-6) M) competitively inhibited the NA-induced contraction, while yohimbine (10(-8)-10(-6) M) did not. 4. Acetylcholine (ACh), sodium nitroprusside (SNP), ATP, ADP, and adenosine caused concentration-dependent relaxations in SBICA following contraction with NA. On the other hand, isoprenaline up to 10(-4) M did not produce any relaxation. The decreasing order of potency of the relaxant agents was ACh greater than SNP much greater than ATP = ADP = adenosine. 5. The ACh-induced relaxation was competitively inhibited by atropine and was abolished by mechanical removal of the endothelium. Aspirin (5 x 10(-5) M) did not affect the relaxant response to ACh, while oxyhaemoglobin (10(-5) M) and methylene blue (10(-5) M) produced significant attenuation. 6. These results suggest that NA produces contraction of the isolated canine SBICA which is mainly mediated via alpha 1-adrenoceptors and that ACh causes a relaxation of the SBICA due to release of endothelium-derived relaxing factor (EDRF) from the endothelial cells.

Acetylcholine↗
PubMed1990

Effects of atrial natriuretic peptide on isolated bovine mesenteric lymph vessels.

The mode of action of atrial natriuretic peptide (ANP) on bovine mesenteric lymphatics was investigated by recording isometric tensions in isolated cylindrical segments. ANP in concentrations from 5 to 30 ng/ml caused dose-related decreases in the rhythm and amplitude of spontaneous contractions. No tachyphylaxis was observed in the ANP-induced responses in lymph vessels. Addition of ANP in a low concentration ranging from 3 to 100 ng/ml produced a dose-dependent relaxation in the lymphatic preparations precontracted by 10(-7) M bradykinin. The ANP-induced relaxation was not modified by pretreatment with 5 x 10(-7) M propranolol, 5 x 10(-7) M atropine, 10(-6) M cimetidine, 5 x 10(-5) M aspirin, or 10(-5) M ouabain. The mechanical rubbing of endothelial cells in the lymph vessels caused no significant effect on the ANP-induced relaxation. The relaxation, however, was significantly reduced by pretreatment with 10(-5) M methylene blue. These results suggest that ANP in a low concentration seems to inhibit lymph transport through a reduction of spontaneous contractions and a marked relaxation of lymphatic smooth muscles in bovine mesenteric lymphatics and that ANP may produce the relaxation through synthesis of guanosine 3',5' cyclic monophosphate, independent of the lymphatic endothelium.

Animals↗
PubMed1990

Endothelium and mechanical responses of isolated monkey pulmonary veins to histamine.

Ring strips of monkey pulmonary veins precontracted with a high concentration of prostaglandin F2 alpha (PGF2 alpha) relaxed in a concentration-dependent manner in response to histamine. Treatment with mepyramine and/or famotidine attenuated the relaxation. 2-Pyridylethylamine (2PEA) and dimaprit caused relaxations in the precontracted preparations, which were inhibited by pretreatment with mepyramine and famotidine, respectively. Removal of endothelium reversed the histamine- and 2PEA-induced relaxations to dose-related contractions. On the other hand, the removal had no effect on the dimaprit-induced relaxations, which were significantly reduced by pretreatment with famotidine. Histamine-induced relaxations in the precontracted strips with endothelium in the presence and absence of famotidine were suppressed or abolished by treatment with methylene blue or hemoglobin but were unaffected by aspirin. It may be concluded that histamine-induced relaxation in monkey pulmonary veins precontracted with PGF2 alpha is mediated by H2-receptors in smooth muscle and H1-receptors in endothelium. Also, stimulation of the endothelial H1-receptors liberates an endothelium-derived relaxing factor.

Animals↗
PubMed1990

Age-related changes in relaxant response of vascular smooth muscles to atrial natriuretic peptide.

The effect of aging on responses of vascular smooth muscles to atrial natriuretic peptide (ANP) and other vasodilator substances was investigated in isolated rat aortae, rat renal arteries and monkey renal arteries which were precontracted with norepinephrine. There was no significant difference in the ANP-induced maximum relaxation between young and old rat aortae. However, the concentration of agonists causing a 50% relaxation (ED50) value for the old rats was 7.3 times greater than that for the young ones. In rat and monkey renal arteries, the ED50 ratios were 6.2 and 3.8, respectively. The relaxant responses of the rat aortae to isoproterenol and acetylcholine also decreased with increasing age. The ED50 ratios for isoproterenol and acetylcholine were more than 40 and 17, respectively. The maximum relaxation induced by 10(-5) M isoproterenol also decreased significantly in the aortae from the older rats. On the other hand, the ED50 for nitroprusside, nifedipine- and potassium-induced relaxation was not affected by increasing age. These results suggest that ANP-induced relaxation of vascular smooth muscles is reduced with increasing age in rat aortae, rat renal arteries and monkey renal arteries. The mechanisms by which the ANP-induced relaxation decreased in association with the aging process may be quite different from those in acetylcholine-induced and beta adrenoceptor-induced relaxation.

Acetylcholine↗
PubMed1990

Effects of vasoconstrictive and vasodilative agents on lymphatic smooth muscles in isolated canine thoracic ducts.

A study was made of the isometric responses of isolated canine thoracic ducts to several physiological vasoactive substances. Contractions of the lymphatic smooth muscles were induced by epinephrine, norepinephrine, 5-hydroxytryptamine, histamine (HIS) and prostaglandin F2 alpha in a dose-dependent manner. The decreasing order of potency in the contractile responses was as follows: epinephrine greater than norepinephrine greater than 5-hydroxytryptamine much greater than HIS not equal to prostaglandin F2 alpha. There were no significant regional differences in the responses to vasoconstrictive agents. Phenylephrine, xylazine and clonidine caused a dose-dependent contraction in the lymphatic preparations. Prazosin (10(-8) to 10(-7) M) inhibited the phenylephrine-induced vasoconstriction in a competitive manner. Xylazine-induced responses were inhibited competitively by yohimbine (10(-8) to 10(-7) M). These results suggest that both alpha-1 and alpha-2 adrenoceptors are located on the lymphatic smooth muscles of canine thoracic ducts. On the other hand, acetylcholine, isoproterenol, HIS, adenosine and ATP caused dose-dependent relaxations in canine thoracic ducts precontracted by 10(-5) M norepinephrine. The decreasing order of potency in the relaxant responses was as follows: acetylcholine much greater than isoproterenol much greater than adenosine not equal to HIS not equal to ATP. There were no significant regional differences in the relaxant responses to the agents. Procaterol, salbutamol, dobutamine and denopamine caused a dose-dependent relaxation of isolated canine thoracic ducts. Propranolol (10(-9) to 10(-8) M) inhibited procaterol- and dobutamine-induced vasorelaxations in a competitive manner. Metoprolol (10(-8) to 10(-7) M) inhibited only the dobutamine-induced vasorelaxation, but did not significantly influence the procaterol-induced response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗