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Biomedical subjects

F Takenaka

Publications and source records attributed to F Takenaka.

At least 19 recordsLinked to original sources
PubMed2001

Effects of alpha-D-glucosylglycerol on the in vitro digestion of disaccharides by rat intestinal enzymes.

Alpha-D-glucosylglycerol (GG) is a mixture of 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG has been found to be slightly hydrolyzed in vitro only by rat intestinal enzymes, but hardly at all by other digestive juices. GG suppressed the hydrolysis of maltose, sucrose and isomaltose by rat intestinal enzymes because the amount of glucose in the digestion of a mixture of GG and disaccharide was less than the sum of that in each individual digestion. The consumption of GG was suppressed by isomaltose, but promoted by maltose, with the hydrolysis of GG being suppressed. Sucrose appeared to suppress only the consumption of S-GG-I, suggesting that S-GG-I was hydrolyzed by the active site of sucrase in a sucrase-isomaltase complex. Transglucosylation seems to have occurred more frequently in the individual digestion of maltose and isomaltose than in that of GG and sucrose. GG seemed to promote transglucosylation in the presence of maltose, to suppress it with sucrose, and to delay it with isomaltose.

Animals↗
PubMed2000

Synthesis of alpha-D-glucosylglycerol by alpha-glucosidase and some of its characteristics.

It has been found that alpha-D-glucosylglycerol (GG) is contained in such traditional Japanese foods brewed by using koji as sake, miso and mirin, and that GG is formed by transglucosylation to glycerol that is produced by yeast with alpha-glucosidase (EC 3.2.1.20) from koji in the sake mash. GG has also been found to consist of three components, 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG was synthesized from a mixture of maltose and glycerol by the batch method, using alpha-glucosidase (transglucosidase L-AMANO). alpha-Glucosidase seemed to be so stable that the amount of GG increased about 5-fold compared with that in the first reaction by the daily addition of maltose for 10 d. Syrupy GG obtained was found to have the following characteristics: about 0.55-fold sweetness compared with sucrose, high thermo-stability, low heat-colorability, low Maillard reactivity, low hygroscopicity, high water-holding capacity, non-cariogenicity and low digestibility.

Animals↗
PubMed2000

Identification of alpha-D-glucosylglycerol in sake.

alpha-D-Glucosylglycerol (GG) was found for the first time in sake (Japanese rice wine) in an amount of about 0.5%. GG was also found in miso and mirin which had been brewed by using koji. GG was hydrolyzed into glucose and glycerol in an equimolar ratio with maltase (EC 3.2.1.20, alpha-glucosidase from yeast), but not with emulsin (EC 3.2.1.21, beta-glucosidase from almond). The retention times and mass spectra of trimethylsilyl derivatives by a GC-MS analysis of GG in sake were comparable to those of various GG samples synthesized by glycol cleavage. It was proven that GG in sake consisted of three components, viz., 2-O-alpha-D-glucosyl-glycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). The ratio of the three components in GG was 6:66:28 for sake. It is considered that GG was formed by transglucosylation of the glucosyl groups to glycerol by alpha-glucosidase from koji in the sake mash.

Chromatography, High Pressure Liquid↗
PubMed1992

Determination of eperisone in human plasma by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed to determine eperisone hydrochloride, 4'-ethyl-2-methyl-3-piperidinopropiophenone hydrochloride, in human plasma over the concentration range 0.2-40 ng/ml. Excellent sensitivity was achieved by selection of a favorable fragment ion, m/z 98, of eperisone and reduction of heat decomposition of eperisone by using a splitless injector and a shortened capillary column. The method described here allows the determination of plasma concentrations as low as 0.2 ng/ml, the concentration attained 6 h after a single oral administration of 50 mg. At eperisone hydrochloride concentrations higher than 0.5 ng/ml, the mean inter-day variation of accuracy of the assay was less than 12%.

Calibration↗
PubMed1981

A further study on constrictor responses of dog coronary arterial strips to acetylcholine under potassium-contracture.

Experiments were designed to clarify what mechanisms are involved in the contraction of dog coronary artery induced by acetylcholine. Helical strips cut from the left circumflex coronary artery were suspended in a bath filled with oxygenated Krebs-Ringer solution at 37 degrees C, and tension developments were recorded isometrically. During potassium-contracture acetylcholine produced further contractions of the strips, which were significantly depressed by atropine together with phentolamine or atropine together with d-tubocurarine. In the strips prepared from dogs in which 6-hydroxydopamine was administered 2 hrs before isolation of hearts, acetylcholine-induced contraction was suppressed by atropine alone. Norepinephrine produced contractions in these strips, which were blocked by phentolamine. Results indicate that acetylcholine may directly constrict the artery through a muscarinic action and simultaneously produce norepinephrine release from sympathetic nerve endings by acting on presynaptic nicotinic receptors resulting in the contraction of the artery.

Acetylcholine↗
PubMed1981

Participation of coronary perfusion pressure in transmural energy metabolism in the hypoperfused canine heart.

The participation of coronary perfusion pressure in hemodynamic and transmural metabolic changes was examined in the open chest canine heart. At lower pressure than 50% of the control, reactive hyperemia disappeared and the coronary arterial inflow precipitously decreased. In 8 dogs, when the coronary arterial inflow was decreased to 47-49% of the control by coronary constriction for 15 min, the coronary perfusion pressure fell in various degrees ranging from 39 to 73% of the control. At a lower pressure than 60% of the control, creatine phosphate (CP) content and its ratio of subendocardium (ENDO) to subepicardium (EPI) decreased, while lactate (LA) content and its ratio of ENDO to EPI increased depending on the degree of the fall in coronary perfusion pressure. A little decrease in ATP content was produced only in the subendocardium under the lower pressure than 50% of the control. When the CP content decreased to below one-third of the control, the significant accumulation of lactate and the precipitous decrease in ATP occurred. Our results suggest that the coronary perfusion pressure has an important role for a severity of the transmural energy metabolism in the hypoperfused ventricle.

Animals↗
PubMed1979

Responsiveness and high-energy phosphate metabolism of isolated dog coronary arteries.

The relationship between responsiveness and high-energy phosphate metabolism was observed in isolated dog coronary arterial strips before and after equilibration, under aerobic conditions. The strips responded slowly to potassium, norepinephrine, isoproterenol and 5-hydroxytryptamine before being equilibrated but did respond quickly to these drugs after being equilibrated for 1 hour under aerobic conditions. The contents of ATP, creatine phosphate (CP) and lactate were not significantly altered before and after equilibration for 1 hr. It is proposed that, before being equilibrated under aerobic conditions, coronary arteries may be unable to utilize ATP and CP due to injury of contractile or relaxant mechanisms resulting in a weak vascular responsiveness.

Adenosine Triphosphate↗
PubMed1979

Effects of 2-nicotinamidoethyl nitrate (SG-75) on dog coronary artery and cat papillary muscle.

Effects of 2-nicotinamidoethyl nitrate (SG-75) on isolated dog coronary artery and cat papillary muscle were investigated. SG-75 dose-dependently relaxed the isolated coronary arterial strips contracted with potassium. Large doses of SG-75 depressed contraction of papillary muscle driven with electrical stimulation and inhibited enhancement of contraction of papillary muscle induced by calcium and isoproterenol. From these results it is suggested that SG-75 may have a weak Ca++-antagonistic action.

Animals↗
PubMed1979

A comparison of enzyme activity for energy production in the myocardium and conduction system.

Specific activities of enzymes in bovine hearts were measured. The enzyme activity ratios between the conduction system and the myocardium were 1.9 for G-6-PDH, 1.2 for PFK, 0.5 for total phosphorylase and LDH, 0.4 for GOT and MDH, 0.3 for SDH, 0.2 for Aldolase and CPK, and 0.1 for alpha GPDH. Approximate values for relative volume of Purkinje cells, nerve fibers and connective tissues in the conduction system were 30%, 8%, and 62%, respectively. It is concluded that activities of enzymes serving for anaerobic glycolysis in Purkinje cells are almost the same or slightly higher than those in the myocardium, and activity of enzyme for pentose shunt in the conductive tissue is higher than that in the myocardium.

Animals↗
PubMed1979

Analysis of vasodilatory action of a new nitroester agent, 2-nicotinamidoethyl nitrate (SG-75).

Effects of 2-nicotinamidoethyl nitrate (SG-75) on cardiovascular system were investigated using whole animals and isolated vascular smooth muscles of dogs and rabbits. In dogs in vivo SG-75 i.v. produced dose-dependent falls in systemic blood pressure (SBP) concomitant with increases in heart rate (HR). Hypotension by SG-75 was not affected by propranolol and atropine but slightly inhibited by diphenhydramine. Norepinephrine (NE) dose-dependently increased SBP, and SG-75 could not affect these effects of NE. In dog coronary arterial strips contracted with potassium, SG-75 produced a dose-dependent relaxation of these strips. These effects of SG-75 were not affected by propranolol and atropine, but slightly inhibited by diphenhydramine. NE dose-dependently increased the tension of helical strips prepared from rabbit femoral artery, rabbit aorta and dog coronary artery. But SG-75 could not alter these effects of NE. The results suggest that SG-75 may have not an adrenergic beta-receptor stimulating action, a muscarinic action and an adrenergic alpha-receptor blocking action, but an inconsiderable histamine-like action. Probably, a main action of SG-75 may be a nitroglycerin-like action.

Animals↗
PubMed1979

Effects of theo-esberiven on the development of collateral circulation in dog hearts.

Effects of Theo-Esberiven, a coronary vasodilator, on the development of collateral circulation were investigated in dogs with their left anterior descending artery chronically occluded. The drug was administered i.v. at 0.1 ml/kg once a day for 1 to 4 weeks after the occlusion. Left circumflex coronary flow in dogs treated with the drug was increased over the value in control ones when measured one week after the occlusion. At the same time, the ratio of retrograde pressure to perfusion pressure, which correlates negatively with the collateral vascular resistance, significantly exceeded the value in control (P less than 0.05). On the basis of observations with blood vessel casts of hearts, distinct anastomoses between the circumflex and anterior descending arteries had already been observed in all preparations from dogs treated for 2 weeks in contrast to the findings seen in control ones. There were less histological changes in myocardial tissue obtained from dogs treated for one week than those in control ones. From these results, Theo-Esberiven appears possibly to accerelate the collateral development at the earlier stages after the coronary occlusion.

Aminophylline↗
PubMed1978

High-energy phosphate metabolism of isolated coronary arteries in the dog.

The correlation between phosphate metabolism and isometric contraction was investigated in helical strips from dog coronary artery. Adenosine triphosphate (ATP) and creatine phosphate (CP) contents of resting strips did not significantly change during anoxia. ATP content remained unchanged during potassium-contracture under aerobic conditions but was significantly reduced by anoxia. Pretreatment with iodoacetate resulted in a striking reduction in ATP content with a less marked decrease in CP content. ATP-depleting effect of iodoacetate was reduced slightly by the addition of pyruvate, but contractile response was not restored. It is considered that high-energy phosphates provided by anaerobic glycolysis can meet the energy requirements of resting coronary vessels but are insufficient for maintaining active tension. In resting strips equilibrated for 2 h in oxygenated bath solution, the reactivity to KCl and anoxia appears to be dependent on the availability of ATP.

Adenosine Triphosphate↗
PubMed1978

[Effects of Theo-Esberiven on the coronary circulation and myocardial metabolisms in dogs (author's transl)].

In isolated dog heart, Theo-Esberiven 0.1 mg, which contains 12 mg proxyphylline, 2.5 mg rutin and 5 mg Melilotus extract, and proxyphylline (12 mg) increased coronary blood flow (CBF) and was associated with increased heart rate (HR) and myocardial contractile force (MCF). The effect of Theo-Esberiven on CBF was about 1.7 times higher than that of proxyphylline. Theo-Esberiven did not significantly affect myocardial oxygen consumption (QO2) and redox potential (deltaEh), while proxyphylline aggravated myocardial metabolisms, as determined from these parameters. Esberiven 0.1 ml, which contains 2.5 mg rutin and 5 mg Melilotus extract, slightly but signficantly increased CBF and decreased QO2 and deltaEh without changing HR and MCF. In situ, intra-coronary injection of either Theo-Esberiven or proxyphylline resulted in a dose-dependent increase in left circumflex coronary flow (LCCF). The effect of Esberiven on LCCF was much less and was slight at the higher doses. Intravenous injection of Theo-Esberiven (0.1 ml/kg) increased LCCF. Besides this change, marked fall in blood pressure and tachycardia were induced by both Theo-Esberiven and proxyphylline without the change in dP/dtmax. Esberiven by the same route led to the decrease in blood pressure associated with HR and dP/dtmax. These results indicate that Theo-Esberiven may be appropriately prescribed for ischemic heart diseases.

Action Potentials↗