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K Teraoka

Publications and source records attributed to K Teraoka.

At least 55 records · Page 3Linked to original sources
PubMed1993

Substance P inhibits catecholamine biosynthesis stimulated by carbamylcholine in cultured adrenal chromaffin cells.

The effect of substance P on catecholamine biosynthesis was examined using cultured bovine adrenal chromaffin cells as a model for the sympathoadrenergic system. Substance P markedly inhibited the formation of [14C]catecholamines from L-[14C]tyrosine stimulated by cholinergic agonist, but caused no significant effect on the biosynthesis stimulated by depolarizing agent. In addition, this inhibitory action was completely prevented by the addition of substance P antagonists. Under the conditions in which the inhibition of catecholamine biosynthesis was observed, substance P also inhibited the influx of extracellular 45Ca2+ into these cells, and this inhibitory action on Ca2+ influx was almost identical to that on the biosynthesis. These results provide evidence for a possible role of substance P as a putative neuromodulator in the sympathoadrenergic system.

Adrenal Medulla↗
PubMed1993

Hyperploidization of V79 cells by K-252a in comparison with demecolcine.

The cellular responses of the V79 cell cycle to K-252a, a protein kinase inhibitor, were examined by flow cytometry (FCM) and by time-lapse videomicrography. At a concentration of 0.5 microM of K-252a for 72 h, V79 cells became hyperploid, having above 32c DNA content. The cycle times in the hyperploidizing process were 11.2 (4c-8c), 16.3 (8c-16c) and 19.3 (16c-32c) hours, values which were less than twice that of the control (10.5 h). After the washout of K-252a, the DNA content was widely distributed in the V79 cell population and hyperploid V79 cells reduced DNA content through a variety of cell division modes. These cellular responses to hyperploidization of V79 cells by K-252a were in reasonable agreement with those by demecolcine.

Animals↗
PubMed1993

Sudden cardiac death from hypertrophic cardiomyopathy and acute idiopathic (Fiedler's) myocarditis: autopsy report.

A 45-year-old man with a rapidly deteriorating heart condition died suddenly, two hours after admission, after resistance to attempts of cardiac pacing. At autopsy, the heart weighed 600g with asymmetric septal hypertrophy. Histological examination revealed an extensive and diffuse disarray of myocardial fibers in the ventricular septum and in the free wall of both ventricles. Pronounced mononuclear cell infiltrations and interstitial edema were distributed widely in both ventricles. There were few abnormal findings in the other organs. The diagnosis was hypertrophic cardiomyopathy accompanied by Fiedler's myocarditis. Such a case appears to be rare.

Cardiomyopathy, Hypertrophic↗
PubMed1993

[Alcohol-related high blood pressure, and erythrocyte Na+/K(+)-ATPase activity, sodium and potassium concentrations].

Erythrocyte Na+/K(+)-ATPase activity (Ery-ATPase) and intra-erythrocyte sodium and potassium concentrations (Ery-Na, Ery-K) were determined in 83 men aged between 36 and 60 years. Volumes of alcohol consumed during the preceding one week (Alc) correlated significantly with blood pressure (BP), but not correlated with Ery-ATPase and Ery-K. Ery-Na showed a week inverse correlation with Alc, but the partial correlation after adjusting Ery-ATPase was not significant. Therefore, elevations of BP found in alcohol consumers are not related to changes in the cell-membrane Na+/K(+)-ATPase activity and intracellular Na and K concentrations. Ery-ATPase showed a borderline significant positive correlation with diastolic BP (0.05 < or = p < 0.10), independently of age, body mass index and Alc. The significance of the weak association in the pathogenesis of hypertension remains unclear.

Adult↗
PubMed1992

Further studies on the relationship between tyrosine supply and catecholamine production in cultured adrenal chromaffin cells.

To elucidate a possible role of tyrosine supply as a factor modulating catecholamine biosynthesis in the adrenergic cell, the transport of [14C]tyrosine into cultured bovine adrenal chromaffin cells was first examined, and the relationship between [14C]tyrosine transport and [14C]catecholamine formation was then investigated. Under the conditions which were routinely employed to determine the rate of catecholamine biosynthesis, tyrosine was taken up into the cells in a manner independent of extracellular Na+ and Ca2+, and this uptake was also insensitive to ouabain and various metabolic inhibitors. The stimulation of these cells with high K+ and other secretagogues caused no significant alteration in the uptake. While, tyrosine transport was markedly inhibited by tyrosine analogues and other L-aromatic amino acids, and this inhibition was accompanied by the reduction of [14C]catecholamine formation. In contrast, tyrosine transport was markedly enhanced by flavone, and this enhancement was also accompanied by the augmentation of catecholamine production under the same experimental conditions. These results seem to indicate that the transport of tyrosine into the cells may be closely related to catecholamine formation within the cells, thus providing an evidence for a possible role of tyrosine supply as one of the factors affecting catecholamine production in the adrenal chromaffin cell.

Adrenal Medulla↗
PubMed1992

[Determination of human erythrocyte membrane Na+/K(+)-ATPase activity in small volume of blood sample].

Na+/K(+)-ATPase of the cell membrane is considered to be closely related to the pathology of various diseases including hypertension and heart failure. The activity of this enzyme in the erythrocyte membrane has been determined in earlier reports by the assay of inorganic phosphate generated from the substrate ATP or radioimmunoassay after binding 3H ouabain to the erythrocyte membrane, using a large volume of blood samples. However, as neither method was appropriate for wide routine use, we developed a method to assay this enzyme in a small volume (10 ml) of fresh human blood samples with re-evaluation of conditions for the inorganic phosphate assay. In this method, the coefficient value (CV) of membrane protein amount and the NA+/K(+)-ATPase activity were 2.2% and 2.5% respectively, indicating sufficient precision of the assay. Moreover, in 97 subjects without abnormalities in blood biochemical tests (77 males and 20 females) aged 35-59 years, the enzyme activity showed no differences according to age or sex, ranging from 0.217 to 0.071 mumols Pi/mg/hr with a mean of 0.130.

Adult↗
PubMed1992

Inhibition by amiloride of ouabain-evoked catecholamine secretion from cultured adrenal chromaffin cells: evidence for its blocking action on interaction between ouabain and Na+/K(+)-pump.

The effect of amiloride on ouabain-evoked catecholamine secretion was investigated in primary cultures of bovine adrenal chromaffin cells. Catecholamine secretion evoked by ouabain was inhibited markedly by amiloride, but the secretion evoked by Na+ removal was not affected by the drug. In contrast, adriamycin, a putative inhibitor of the Na(+)-Ca++ exchange, inhibited the secretion evoked by Na+ removal as well as that evoked by ouabain. The inhibitory action of amiloride on the ouabain-evoked secretion was therefore considered to be due to its action on other mechanism(s) than the Na(+)-Ca++ exchange process. Further studies showed that the uptake of 86Rb+ into the cells was slightly but significantly reduced by amiloride, and the inhibitory action of ouabain on 86Rb+ uptake was considerably blocked by this drug under the experimental conditions in which the inhibition of ouabain-evoked secretion was observed. The binding of [3H] ouabain to the intact cells was also inhibited by amiloride under the same conditions. These results suggest that amiloride may inhibit ouabain-evoked catecholamine secretion as a consequence of blocking the inhibitory action of ouabain on the plasma membrane Na+/K(+)-pump in adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1992

[A flow cytometric study of the effects of benzalkonium chloride on the cell cycle].

The effects of benzalkonium chloride (BAK) on the cell cycle of Chang's cultured human conjunctival cells were investigated by a flow cytometer (FCM). The cells were exposed to BAK solutions for 60 sec and after 12-48 hrs were fixed in 20% ethanol, treated by 0.25% RNase and stained by 0.005% propidium iodide. DNA histograms were analyzed by the FCM. As a result, although many cells were damaged by exposure to solutions of 0.0025% or 0.005% BAK, they began to grow again 48 hrs later. BAK decreased red fluorescence intensity in DNA histograms. The histogram shifted to the left 12 hrs after the cells were exposed to 0.0025% or 0.005% BAK solutions and recovered 48 hrs later. The DNA synthetic phase of the cell cycle was inhibited by exposure to solutions of 0.0025% BAK and then recovered 48 hrs later.

Benzalkonium Compounds↗
PubMed1991

Induction of kinetic cell death and its underlying mechanisms.

Using a modified Langendorff system, we established an experimental model of kinetic cell death in the rat heart. After calcium (5.5 mM) was loaded for 20 min and 10(-7) mol isoproterenol was then delivered to the perfusion medium, the hearts developed tonic contracture. Histological examination of the myocardium revealed widespread kinetic cell death. Stimulation of alpha-adrenoceptors with phenylephrine did not induce kinetic cell death, even after calcium loading. In our kinetic cell death model in the rat, the outflow of creatine phosphokinase into the perfusion medium was increased after isoproterenol application, with a peak occurring at 45 min. The peak transient increase in the intracellular calcium ion concentration (the Ca-transient) was measured using Fura2/AM, and was found to be augmented by increasing the calcium concentration of the perfusion medium. These results suggest that in the presence of an increased intracellular calcium concentration, even slight stimulation of beta-adrenoceptors can easily induce myocardial injury.

Animals↗
PubMed1991

Pharmacological study on Ba2(+)-stimulated catecholamine secretion from cultured bovine adrenal chromaffin cells: possible relation of Ba2+ action to Ca(2+)-activated secretory mechanism.

The stimulatory action of Ba2+ on catecholamine secretion from cultured bovine adrenal chromaffin cells was studied to elucidate a possible relationship between Ba2+ action and the Ca2(+)-mediated secretory mechanism. Catecholamine secretion was dramatically stimulated by Ba2+ in the absence of external Ca2+, and this stimulatory action was observed in a concentration-dependent manner. Ba2+ evoked the concomitant release of dopamine beta-hydroxylase in a similar manner to the Ca2(+)-dependent secretion. The stimulation of catecholamine secretion by low concentrations of Ba2+ was markedly inhibited by protein kinase inhibitors, polymyxin B and trifluoperazine (TFP). The inhibitory action of polymyxin B, but not that of TFP, on the Ba2+ action was attenuated by elevating the concentration of Ba2+ in the incubation mixture. The stimulatory action of Ba2+ was enhanced by a protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). In contrast to the acute effect of TPA, chronic exposure of chromaffin cells to high concentration of TPA reduced catecholamine secretion stimulated by Ba2+ as well as high K+ and carbamylcholine. These findings suggest the possibility that Ba2+ may activate Ca2(+)-mediated secretory processes presumably through its action on protein kinase C, thus resulting in the stimulation of catecholamine secretion from bovine adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1991

Tetrodotoxin-insensitive Na+ channel activator palytoxin inhibits tyrosine uptake into cultured bovine adrenal chromaffin cells.

The effects of the tetrodotoxin-insensitive Na+ channel activator palytoxin on both the secretion of endogenous catecholamines and the formation of 14C-catecholamines from [14C]tyrosine were examined using cultured bovine adrenal chromaffin cells. Palytoxin was shown to cause the stimulation of catecholamine secretion in a concentration-dependent manner. However, this toxin caused the reduction rather than the stimulation of 14C-catecholamine formation at the same concentrations. Palytoxin failed to cause any alteration in the activity of tyrosine hydroxylase prepared from bovine adrenal medulla. Furthermore, the uptake of [14C]tyrosine into the cells was shown to be inhibited by this toxin under the conditions in which the suppression of 14C-catecholamine formation was observed, and this inhibitory action on tyrosine uptake was closely correlated with that on catecholamine formation. The inhibitory action of palytoxin on tyrosine uptake into the cells was observed to be noncompetitive, and this effect was not altered by the removal of Na+ from the incubation mixture. These results suggest that palytoxin may be able to inhibit the uptake of [14C]tyrosine into the cells, resulting in the suppression of 14C-catecholamine formation, probably through its direct action on the plasma membranes of bovine adrenal chromaffin cells.

Acrylamides↗
PubMed1991

Clinical and pathologic studies on contraction band lesion: relation to acute myocardial infarction and unexplained sudden death.

The relation between contraction band lesion (CBL) and major cause of death was investigated through the use of hearts from 500 serialized autopsy cases. Acute myocardial infarction (AMI), unexplained sudden death (USD), cardiac surgery death, cancer, infection, cerebrovascular disease, and ruptured aortic aneurysm were examined with respect to age, sex, heart weight, and CBL localization patterns. CBL was observed frequently with AMI, USD, and cardiac surgery death, but virtually unseen with cancer or in the remaining disease categories. In a comparison of average heart weight among the various groups, there appeared to be a correlation between heavy heart weight and increased frequency of CBL. In a second investigational phase, the relation between CBL and application of cardiopulmonary resuscitation techniques was investigated in 100 separate autopsy cases. There was no significant difference between treated and untreated patients regarding frequency and pathology of CBL. We hypothesize that CBL-AMI and CBL-USD belong to the same disease group and that CBL develops before the onset of death with no connection to the mechanical and pharmacologic effects of cardiopulmonary resuscitation.

Adolescent↗
PubMed1990

Stimulatory actions of bioflavonoids on tyrosine uptake into cultured bovine adrenal chromaffin cells.

The effects of flavonoids on L-[14C]tyrosine uptake into cultured adrenal chromaffin cells were examined. Flavone markedly stimulated tyrosine uptake into these cells in a manner dependent on its concentration. Apigenin also caused a moderate stimulatory action, but quercetin had no significant effect on the uptake. Flavone also stimulated the uptake of histidine, but did not affect the uptake of serine, lysine, or glutamic acid. These results are considered to propose the possibility that flavonoids may be able to stimulate the precursor uptake into the cells, resulting in an enhancement of the biogenic amine production.

Adrenal Medulla↗
PubMed1990

Stimulatory action of Ba2+ on catecholamine biosynthesis in cultured bovine adrenal chromaffin cells: possible relation to protein kinase C.

The effect of Ba2+ on the catecholamine biosynthetic activity was studied by measuring the formation of [14C]catecholamines from L-[14C]tyrosine in cultured adrenal chromaffin cells. In the absence of Ca2+, [14C]catecholamine formation was markedly stimulated by Ba2+, and this stimulation was observed in a manner dependent on its concentration. The stimulation of [14C]catecholamine formation by relatively low concentrations of Ba2+ was suppressed by polymyxin B, a typical inhibitor of Ca2+/phospholipid-dependent protein kinase (protein kinase C); and this inhibitory action of polymyxin B was attenuated by increasing the Ba2+ concentration. On the other hand, a tendency toward the enhancement of Ba2+-stimulated [14C]catecholamine formation was observed by a protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). In contrast to the acute effect of TPA, [14C]catecholamine formation stimulated by Ba2+ was reduced by long-term exposure of chromaffin cells to a high concentration of TPA, which has already been reported to cause the reduction of protein kinase C activity as a result of the down-regulation of this enzyme. These findings suggest that Ba2+ stimulates catecholamine biosynthesis, probably through its direct action on protein kinase C in adrenal chromaffin cells.

Adrenal Glands↗
PubMed1990

Variations in intrathyroidal lithium content and their effect on the iodide uptake in mouse thyroid.

Lithium (Li) is accumulated in the thyroid but the mechanism of Li accumulation is not known. In the present study, the causes of variation in Li concentration in the thyroid and the relation between cellular Li and iodide were examined. This was done by using mice treated with Li (0.01% as Li2CO3) for 4 weeks, co-administered with propylthiouracil (PTU, 0.5 mg/ml daily p.o.) or thyroxine (T4, 0.5 micrograms per day i.p.) for last 10 days. The total content of Li in a whole thyroid (ng/thyroid) was not changed through treatment with PTU or T4. But the Li concentration in terms of mg/kg of the gland was reduced with PTU and was unchanged or slightly increased with T4, due to the change in the mass of thyroid. Furthermore, short-term (3 h) Li uptake in the thyroid was not affected by pre-treatment with PTU or T4. These results indicate that the variation in thyroidal Li concentration was not due to a direct effect of PTU or T4 on Li transport, but to a thyroidal condition caused by the secondary influence of drugs. A measurement of the thyroid: serum iodide concentration ratio (T/S) of 125I showed that the iodide uptake was reduced when intracellular Li concentration was high, and that PTU alone elevated the T/S, but Li + PTU brought it back to a normal level; whereas, T4 alone diminished the T/S, Li + T4 made it rise significantly more than did T4 alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗