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Biomedical subjects

K Itaya

Publications and source records attributed to K Itaya.

At least 37 records · Page 2Linked to original sources
PubMed1981

[Detection of exercise induced left ventricular asynergy by two-dimensional echocardiography (author's transl)].

In order to detect an exercise induced asynergy, cross-sectional echocardiography was performed during multistage maximal bicycle ergometer stress test in the supine position. 1) Left ventricular (LV) asynergy occurred earlier than or simultaneously with the appreciable ST segment change. 2) In patients with angina, LV asynergy appeared in the area of dominant coronary stenosis, while ST depression was seen in V3-6 as well as II, III and aVF, despite of the localized area of asynergy. 3) In patients with myocardial infarction, LV asynergy increased or extended over or around the infarcted area except one case, ST segment elevated in the leads over the infarction with abnormal Q waves and depressed in the reciprocal leads. These observations revealed that ST depression does not necessarily mean an occurrence of new ischemia over the corresponding area in myocardial infarction. Thus exercise cross-sectional echocardiography was demonstrated to be a good method to detect an exercise induced ischemia and would be particularly valuable in view of the coronary artery bypass.

Adult↗
PubMed1980

Effects of oral befunolol on heart rate and systolic blood pressure during submaximal exercise in man.

For the purpose of determining exercise intensity required for evaluating the effect of beta-blocking agents, the multi-stage treadmill exercise was carried out up to intensity of 85% of maximal oxygen intake (VO2max) after administration of beta-blocking agents in 7 healthy men. To obtain a stable dose response in the inhibitory effect of beta-blocking agents on heart rate (HR) and systolic blood pressure (S-BP), the exercise intensity more than 65% of VO2max (75% of maximal heart rate) was needed. In order to evaluate the effect of befunolol (BFE), a submaximal treadmill exercise of 75% of the age adjusted predicted maximal heart rate was loaded in 6 healthy men at 1.5, 4, and 8 hours following a single oral administration of 10 mg, 20 mg or 40 mg of BFE and 20 mg or 40 mg of propranolol. Simultaneously, the plasma concentration of BFE was determined 1.5, 4, 6 and 8 hours after the administration of BFE at each dose. In human serum, BFE was detected together with its metabolite, revealing a significant correlation between BFE and metabolite (r = 0.94, p < 0.001). Almost a certain rate of metabolite (4--5 times) was detected against BFE. As for the biological half life, it was 1.79 +/- 0.13 hours with BFE and 3.67 +/- 1.33 hours with metabolite. The inhibitory effect of BFE on HR and S-BP during exercise exhibited a dose response with the oral dose and its plasma concentration, and was almost twice as much as that of propranolol at the same dose. Accordingly, the myocardial oxygen consumption which may be represented as rate pressure product was inhibited twice as much as propranolol. BFE is characteristic of its more rapid elimination of its effect compared to the other beta-blocking agents. The decrease in the inhibitory effect of BFE or HR during exercise was about 1.8 times quicker than that of propranolol.

Administration, Oral↗
PubMed1979

Effect of ethanol on adrenaline-stimulated glucose uptake in rat white adipose tissue.

The effect of ethanol on adrenaline-stimulated glucose uptake by rat white adipose tissue has been examined in vitro. Ethanol (3%) inhibited the stimulatory effect of adrenaline on glucose uptake whereas it failed to inhibit the effect of adrenaline on free fatty acid production. Addition of calcium (12.5 mM) to the incubation medium restored adrenaline's effect on glucose uptake. Addition of propranolol also restored the effect of adrenaline inhibited by ethanol. Ethanol did not inhibit insulin-stimulated glucose uptake. These results suggest that ethanol modifies the coupling of the adrenoceptor to the glucose transport system in adipose tissue that is stimulated by adrenaline.

Adipose Tissue↗
PubMed1979

Effect of 5-hydroxytryptamine on blood glucose and cyclic AMP in the rat.

The effects of 5-hydroxytryptamine (5-HT) on plasma cyclic AMP (cAMP) and glucose concentrations were studied in rats in vivo. 5-HT injected i.p. increased plasma cAMP and glucose. Injections of propranolol, hexamethonium, and cyproheptadine inhibited the 5-HT-induced increase in glucose but not in cAMP. Atropine did not inhibit the action of 5-HT. These effects of 5-HT were not seen in adrenomedullectomized rats, and 5-HT did not elevate the concentration of plasma cAMP in anti-glucagon antiserum-injected rats. These results confirm the previously reported finding that 5-HT-induced increase in blood glucose is mediated via adrenaline released from adrenal medulla by 5-HT and suggest that the increase in plasma cAMP, induced by 5-HT, is due to glucagon released by an unknown factor, or factors other than adrenaline released from the adrenal medulla by 5-HT.

Adrenal Medulla↗
PubMed1979

Inhibitory effect of 5-hydroxytryptamine on lipogenesis in rat adipose tissues.

5-Hydroxytryptamine (5-HT) inhibited the incorporation of 14C from 14C-labelled glucose, pyruvate, citrate and acetate into fatty acids but it did not inhibit the conversion of 14C from citrate and acetate into CO2, and the citrate conversion into glyceride-glycerol in epididymal and mesenteric adipose tissue from 24h-fasted rats. 5-HT stimulated the formation of lactate from glucose and pyruvate, and increased the ratio of lactate produced/pyruvate taken up. This ratio was similar to the NADH:NAD ratio. These results indicate that 5-HT inhibits fatty acid synthesis in rat white adipose tissue by mechanisms similar to those of the catecholamines.

Acetates↗
PubMed1979

[Effects of gamma-oryzanol on norepinephrine contents in the brain and stomach of rats (author's transl)].

Norepinephrine (NE) content in the brain slightly but significantly increased when gamma-oryzanol (100 mg/kg, s.c.) was given once daily for 1, 5 or 10 days, while NE in the gastric area was not affected. The turnover rate of brain NE tended to decrease with the administration of gamma-oryzanol. From the results, it is likely that successive doses of gamma-oryzanol increase brain NE by inhibiting degradation or release of NE.

Animals↗
PubMed1978

Differences in responsiveness to adipokinetic agents between white epididymal and brown interscapula adipose tissue from rats.

Lipolytic activity was studied in brown and white adipose tissue of rats in vitro. 5-Hydroxy-tryptamine (5-HT), phenylephrine, noradrenaline, adrenaline and isoprenaline were used as adipokinetic agents. All stimulated lipolysis in brown adipose tissue, but 5-HT and phenyl-ephrine did not in white adipose tissue. A beta-blocking drug, propranolol, inhibited the stimulatory effect of the agents in both adipose tissues. However, an alpha-blocking drug, phentolamine, further increased the lipolysis induced by noradrenaline or adrenaline in brown adipose tissue and inhibited the effect of isoprenaline. In white adipose tissue, its action was to marginally decrease the effect of adrenaline and noradrenaline. Increase in the pH of the incubation medium stimulated FFA and glycerol release in brown adipose tissue, but not in the epididymal adipose tissue. This effect of pH on lipolysis was further enhanced by phentolamine and decreased by propranolol. Increase of lipolysis with pH was not seen with brown fat tissue from the reserpine-treated rats. These results show that brown adipose tissue of the rat has an alpha-receptor with inhibitory effects on lipolysis that is affected by alpha- or mixed-type adrenergic agonists, noradrenaline and adrenaline.

Adipose Tissue↗
PubMed1978

[Effects of gamma-oryzanol on gastric secretions in rats (author's transl)].

gamma-Oryzanol has been reported to inhibit gastric secretion and experimental ulcers in rats. In this paper, the inhibitory effects of gamma-oryzanol on gastric secretions caused by three stimulants have been compared. gamma-Oryzanol was slightly effective for histamine-stimulated acid secretion, non effective for carbachol-stimulated secretion and significantly inhibited the tetragastrin-stimulated secretion. The effect of gamma-oryzanol on acid secretion stimulated by tetragastrin was prevented by vagotomy but not by splanchnicotomy. It is assumed that the gastric antisecretory effect of gamma-oryzanol is mediated by the vagus nerve which plays a role in the action of gastrin.

Animals↗
PubMed1978

[Effects of gamma-oryzanol and atropine on gastric secretion stimulated by insulin or 2-deoxy-D-glucose (author's transl)].

The inhibitory effects of gamma-oryzanol and atropine on the gastric secretion were studied using insulin and 2-deoxy-D-glucose as vagal stimulants. Pretreatment with gamma-oryzanol (100 mg/kg, s.c., once daily x 5) depressed the gastric secretion stimulated by insulin or 2-deoxy-D-glucose, but the potency was less than that with atropine (10 mg/kg, s.c.). gamma-Oryzanol had no effect on decrease in the serum glucose level or on increase in the gastrin level induced by insulin injection, while atropine enhanced these responses. From these results, it is considered that the inhibitory action of gamma-oryzanol on gastric secretion may be due to depression of the vagus system but the mode of action is different from that of atropine.

Animals↗
PubMed1977

Increased absorption of iodochlorhydroxyquin by rat intestine in the presence of solubilizing agents.

The intestinal absorption of iodochlorhydroxyquin (clioquinol) by the rat was studied by determining the radioactivity in the bile, blood and several organs 90 min after direct application of 125I-labeled clioquinol into the duodenum. The addition of solubilizing agents such as carboxymethyl-cellulose and lauryl sulfate to clioquinol preparation markedly enhanced the intestinal absorption of the drug in either the presence of absence of bile secretion which, by itself, increased the drug absorption. Possible significance of the enhanced absorption of clioquinol by solubilizing agents in the etiology of subacute myelo-optic neuropathy (SMON) in Japan is discussed.

Animals↗
PubMed1977

[Studies on gamma-oryzanol. III. Influence of gamma-oryzanol on circadian rhythms of serum gastrin, 11-OHCS and gastric secretion in rats (author's transl)].

In the course of investigations of gamma-oryzanol in rats, circadian rhythms in antiulcerogenic action on gamma-oryzanol were observed. Circadian rhythms in several other parameters were investigated and correlated with the antiulcerogenic action. Pretreatment of rats with gamma-oryzanol 100 mg/kg, s.c., for 5 days tended to decrease serum gastrin levels and gastric secretion, and to increase serum 11-OHCS. Suppresive patterns of serum gastrin and gastric secretion following the pretreatment with gamma-oryzanol corresponded to the circadian rhythms in antiulcerogenic action of gamma-oryzanol. A complication of our results suggests that increment of catecholamines in rat brain after gamma-oryzanol plays a role in the above mentioned actions.

11-Hydroxycorticosteroids↗
PubMed1977

A more sensitive and stable colorimetric determination of free fatty acids in blood.

A sensitive method is proposed for the colorimetric determination of free fatty acids (FFA). Diphenylcarbazide containing diphenylcarbazone is used as the color developing reagent instead of diethyldithiocarbamate which was employed in the previous method (1965). J. Lipid Res. 6: 16-20). The present method was successfully applied to the determination of FFA present in as little as 40 microliter of whole blood.

Animals↗