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Biomedical subjects

H Satoh

Publications and source records attributed to H Satoh.

At least 793 records · Page 44Linked to original sources
PubMed1987

[Stressor controllability and brain noradrenaline turnover in rats].

A series of experiments examined the effects of a purely psychological factor in a stressful situation (i.e., the ability to manage a stressor or inability to do so) on noradrenergic metabolism in regional rat brains. In Experiment 1, uncontrollable rats which could not escape and avoid electric shock developed more gastric ulceration than did controllable rats which had exactly the same shock but could exert control over the shock. In Experiment 2, the uncontrollable rats displayed sustained increases in noradrenaline (NA) turnover in various brain regions regardless of stress durations. After the controllable rats had firmly mastered the coping response, excess NA utilization at the earlier stage of stress was reduced in many brain regions. These findings suggested that noradrenergic neuronal activity in some specific brain regions, such as the hypothalamus and limbic areas, might be involved in the coping processes under a stressful situation. This hypothesis was supported by the results of Experiment 3 showing that the effects of stressor controllability on regional brain NA turnover were covaried with the complexity of coping task required. Taken together, it is concluded that the degree of behavioral control (the ability to alter the termination or duration) that an organism has over a stressor modulates the physiological and neurochemical impact of that stressor, and that brain NA is implicated in the learning process where an organism copes with a stressor.

Animals↗
PubMed1987

[Clinical study of urinary tract infections in transurethral surgery].

Effect of prophylactic administration of antimicrobials on postoperative urinary tract infection was studied in 40 patients who had undergone transurethral surgery. Two gm of cefoperazone (CPZ) per day was administered intravenously starting on the day of surgery for 5 days consecutively. In group I, 1 g of CPZ was administered 1 hour before surgery and another 1 g after surgery, while in group II 2 g of CPZ was administered after surgery only. Thereafter, in either group, 1 g of CPZ was administered intravenously 2 times a day. Urinary tract infection (UTI) was diagnosed when urine specimens yielded 1 X 10(4)/ml or more cells. In group I, 8 patients (40%) had UTI before surgery. Of 8 patients, 3 had bacteria resistant to CPZ. Of the remaining 5 patients with bacteria sensitive to CPZ 4 patients were cleared of bacteria after surgery. All these patients had bacteria sensitive to CPZ and therefore all were cleared of bacteria after surgery. In either group of patients all without bacteriuria at the time of preoperative evaluation were free from bacteriuria after surgery. All bacteria yielded after surgery were weak pathogens. All patients except 1 had no postoperative infectious complication such as septicemia, epididymitis and UTI. One patient showed UTI with fever after surgery. Urine culture yielded S. faecalis. This study showed that the prophylactic administration of antimicrobials for patients undergoing transurethral surgery was valuable, but the both methods of administration were similarly effective.

Adult↗
PubMed1986

Spizofurone, a new anti-ulcer agent, increases alkaline secretion in isolated bullfrog duodenal mucosa.

The effect of spizofurone, a new anti-ulcer agent, on alkaline secretion was studied in an isolated sheet of bullfrog (10(-4)-10(-3) M) as well as prostaglandin E2 (PGE2, 10(-8)-10(-5) M) added to the nutrient solution increased alkaline secretion, transmucosal potential difference (PD) and short-circuit current (Isc), in a concentration-dependent manner. The maximum increases in alkaline secretion stimulated by spizofurone and PGE2 were much the same. Spizofurone also showed this effect when added to the secretory solution while PGE2 did not. Treatment with indomethacin partly but significantly inhibited the effect of spizofurone, but did not affect that of PGE2. These results indicate that the increase in alkaline secretion in bullfrog duodenal mucosa seen in the presence of spizofurone is mediated, at least in part, by stimulation of endogenous PGs synthesis.

1-Methyl-3-isobutylxanthine↗
PubMed1986

Electrophysiological study of alinidine in voltage clamped rabbit sino-atrial node cells.

Electrophysiological effects of alinidine on rabbit sino-atrial node cells were examined. Alinidine was applied in concentrations between 0.3 and 100 micrograms/ml and decreased the spontaneous frequency in a dose-dependent manner. The maximum rate of rise and the amplitude of action potentials of the spontaneously beating rabbit sino-atrial node were decreased in the presence of alinidine concentrations higher than 10 and 100 micrograms/ml, respectively. The maximum diastolic potential was depolarized by alinidine at 100 micrograms/ml. The main effect of alinidine was a dose-dependent decrease in slope of diastolic depolarization (a prolongation of the cycle length) and a delayed repolarization of the action potential. In voltage clamp experiments, alinidine suppressed the slow inward current (Is) and the outward current (Ik) dose dependently, without altering steady-state inactivation of Is (f infinity) and the activation of Ik (p infinity). The hyperpolarization-activated inward current (Ih) was also reduced. These results suggested that alinidine decreased Is, Ik and Ih due to reduction in the conductance of these current systems. The changes in the ionic currents in the presence of alinidine can explain the changes in configuration of the action potential and must contribute to the negative chronotropic action of alinidine.

Action Potentials↗
PubMed1986

Mercury-selenium interaction in workers exposed to elemental mercury vapor.

Mercury (Hg) and selenium (Se) levels were determined for erythrocytes, plasma and urine of 25 male and 29 female workers exposed to elemental mercury (Hgo) vapor. Interrelationship between the Hg levels and the Se levels was examined by the correlational analysis and the stepwise regression analysis. Indicators of Se status (erythrocyte Se levels, plasma Se levels and urinary Se levels) were closely intercorrelated; similarly, indicators of exposure to Hgo vapor (erythrocyte inorganic Hg levels, plasma Hg levels and urinary Hg levels) were significantly intercorrelated. Since plasma Hg level was one of the significant independent variables in determining the erythrocyte Se and plasma Se levels, Hgo vapor exposure was thought likely to influence the Se metabolism in workers. None of the Se status indicators were significant as determinants of the indicators of Hgo vapor exposure.

Adult↗
PubMed1986

Distribution of mercury in guinea pig offspring after in utero exposure to mercury vapor during late gestation.

Organ distribution of mercury after in utero mercury vapor exposure was investigated in neonatal guinea pigs. Mother guinea pigs in late gestation were exposed to 0.2-0.3 mg/m3 mercury vapor 2 h per day until giving birth. Mercury concentrations in neonatal brain, lungs, heart, kidneys, plasma and erythrocytes were much lower than those of maternal organs and tissues. Neonatal liver, however, showed a mercury concentration twice as high as maternal liver. Mercury concentration ratios of erythrocytes to plasma in offspring were quite different from those of mothers, being 0.2-0.4 for offspring, and 1.3-3.0 for mothers. These results suggested that mercury vapor metabolism in fetuses was quite different from that in their mothers. This may be due to the different blood circulation, as mercury vapor transferred through the placental barrier would be rapidly oxidized into ionic mercury in fetal liver and accumulated in the organ. The different mercury vapor metabolism may prevent fetal brain, which is rapidly developing, and thus vulnerable, from being exposed to excessive mercury vapor.

Animals↗
PubMed1986

An electrophysiological study of amiloride on sino-atrial node cells and ventricular muscle of rabbit and dog.

Effects of amiloride were studied on canine and rabbit sino-atrial node cells and the canine ventricular cells. In the canine sino-atrial node selectively perfused with Tyrode solution through the sinus node artery, amiloride (4.4 X 10(-4)-1.3 X 10(-2)mol/l) induced a negative chronotropic and a positive inotropic effect in a concentration-dependent manner. In canine ventricular muscle, the amplitude of the action potential and the resting membrane potential were decreased in the presence of amiloride (4.4 X 10(-6)-8.7 X 10(-4) mol/l). The maximum rate of rise was also depressed in a use-dependent manner as well as a concentration-dependent manner. Simultaneously the action potential duration was markedly prolonged. Low concentrations of amiloride decreased the contractile force, but higher concentrations (over 8.7 X 10(-5) mol/l) enhanced it. In the spontaneously beating rabbit sino-atrial node, amiloride (8.7 X 10(-5)-2.2 X 10(-3) mol/l) lengthened the action potential duration and the cycle length accompanied with the decreases in the amplitude and the maximum rate of rise of the action potential. The maximum diastolic potential was slightly depolarized. In voltage clamp experiments of the rabbit sino-atrial node, amiloride (4.4 X 10(-4)-1.3 X 10(-3) mol/l) suppressed the slow inward current (Isi) and the outward current (Ik) concentration-dependently, without altering steady-state inactivation of Isi (f infinity) and the activation of Ik (p infinity). The hyperpolarization-activated inward current (Ih) was also reduced. These results suggest that amiloride decreased Isi, Ik and Ih by a reduction in the conductance of these current systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1986

5-Hydroxytryptamine and (+)-lysergic acid diethylamide displace [3H]thyrotropin-releasing hormone at its binding sites in the rat limbic forebrain.

Binding of [3H]thyrotropin-releasing hormone (TRH) to its receptors in the rat limbic forebrain was partially displaced by 5-hydroxytryptamine (5-HT, ligand for 5-HT1 receptors) and (+)-lysergic acid diethylamide ((+)-LSD, ligand for 5-HT1 and 5-HT2 receptors) at nanomolar concentrations. Spiperone (ligand for 5-HT2 receptors) displaced [3H]TRH in a dose-dependent manner at micromolar concentrations. These results suggest that some TRH receptors are related to 5-HT1 receptors, probably adjoining them on the membrane. This type of TRH receptor is shown to be among the high-affinity receptors which we reported previously. The significance of the receptor-coexistence is such that TRH facilitates serotonergic transmission by increasing the density of 5-HT1 receptors. This finding seems to support a pharmacological observation of other investigators that TRH potentiates 5-HT-induced hyperactivity in mice, probably by affecting postsynaptic 5-HT receptors.

Animals↗
PubMed1986

Beta-thromboglobulin release within coronary circulation--a potential role of platelets in ergonovine-induced coronary vasospasm.

The role of platelets in the pathogenesis of acute myocardial ischemia is not yet agreed upon. In this study, the gradient of plasma beta-thromboglobulin concentration between coronary sinus and aorta was used as an indicator of platelet activation within the coronary circulation. Blood samples were drawn before and after injection of ergonovine maleate in patients without fixed coronary stenosis in whom significant coronary spasm was induced by ergonovine (n = 8, Group 1), patients with significant stenosis (greater than or equal to 75%) of the left anterior descending artery and positive ergonovine test (n = 7, Group 2) and patients with significant stenosis of left anterior descending coronary artery and negative ergonovine test (n = 11, Group 3). Fifteen patients with normal coronary arteries who were negative in the ergonovine test served as controls (Group 4). After the ergonovine test, all Group 1 patients revealed a significant increase of beta-thromboglobulin gradient (P less than 0.001), while those in other groups did not. Additionally, the gradient after the ergonovine test of Group 1 patients was larger than those of the other groups (P less than 0.01). All blood samples after the ergonovine test were collected before or at the onset of angina attacks. These results suggest that platelet activation within the coronary circulation has some pathogenic role, probably as an aggravating factor, in coronary artery spasm.

Adult↗
PubMed1986

Generation and dose as modifying factors of inorganic mercury accumulation in brain, liver, and kidneys of rats fed methylmercury.

Through three generations, male rats were fed a commercial chow supplemented with four levels of methyl mercury; the average mercury concentrations were 0.038, 0.18, 7.23, and 33.92 nmol Hg/g food for control, low, middle, and high dose groups, respectively. No clinical abnormalities except enlarged kidneys were found in these animals. The effects of dose and generation on tissue distribution and accumulation of inorganic mercury and total mercury were studied in the brain, kidneys, and liver. The dose level of methyl mercury greatly determined the organ accumulation of total mercury and inorganic mercury, as well as the ratio of inorganic mercury concentration to total mercury concentration (I/T) in organs. The I/T ratio was inversely related to the dose level of methyl mercury. With generational procession, the most notable change was found in the liver, i.e., the increasing I/T ratio and the decreasing total mercury accumulation at any dose level. In contrast, the I/T ratio in the kidney showed no constant tendency with generation. The present results suggest that the generational enhancement of inorganic mercury formation from methyl mercury occurs mainly in the liver.

Animals↗