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Biomedical subjects

F Takenaka

Publications and source records attributed to F Takenaka.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1978

Comparison of myocardial and adipose tissue lipase activity in the rat.

Effects of catecholamines and iodoacetamide on lipase activity (pH 6.8) and triglyceride mobilization were investigated in adipose tissue, myocardial slice and isolated perfused heart preparation of the rat. Epinephrine and isoproterenol did not enhance myocardial lipase activity in vitro and in perfused hearts. No detectable amount of fatty acid was released from myocardial slice by epinephrine in vitro. Epinephrine, however, induced an increase in lipase activity and in the amount of fatty acid released from the adipose tissue. The results suggest a difference in properties of lipase present in the myocardium and in the adipose tissue. Iodoacetamide decreased lipase activity in vitro both in the myocardium and in the adipose tissue. Triglyceride content in the perfused heart receiving iodoacetamide at 30 min of perfusion was higher than that of the control. However, there was no correlation between triglyceride mobilization and lipase activity in these 2 tissues.

Adipose Tissue↗
PubMed1978

Effect of verapamil on the transmural energy metabolism in the isoproterenol-induced myocardial lesion.

The effect of verapamil on the isoproterenol (ISO)-induced transmural metabolic lesion in the left ventricular wall was investigated in the rat heart. The treatment with ISO 2.5 mg/Kg s.c. on 2 consecutive days resulted in significant decreases of creatine phosphate in the subendocardium (ENDO) and of adenosine triphosphate in the ENDO and the subepicardium. On the other hand, inorganic phosphate (Pi) and lactate (LA) were increased in both layers. These changes were more prominent in the ENDO. Pretreatment with verapamil 25 mg/Kg s.c. prevented the reduction of high energy phosphate compounds and the increases of Pi and LA in both layers by ISO.

Adenosine Triphosphate↗
PubMed1978

Effects of dobutamine on coronary circulation and cardiac metabolism of the dog.

Effects of (+/-)-4-[2-(3-p-hydroxyphenyl-1-methyl-amino)ethyl]pyrocatechol (dobutamine) on coronary circulation and cardiac metabolism were investigated using the heart in vivo and the isolated perfused heart of dogs. In the heart in vivo dobutamine 1--30 microgram/kg i.v. and 1--100 microgram i.c. produced dose-dependent increases in coronary perfusion pressure, coronary blood flow, heart rate and left intraventricular pressure. In the perfused heart dobutamine 10 microgram i.c. increased coronary flow, heart rate, cardiac contractility and myocardial oxygen consumption. Delta redox potentials decreased but did not show negative values. Propranolol 0.1 mg/kg i.v. and 0.1 mg i.c. inhibited these effects of dobutamine. Dobutamine shows basically the same actions as isoproterenol, but does not reduce the coronary perfusion pressure by the relatively high dose applied. The results suggest that dobutamine may have a selective adrenergic beta 1 receptor stimulating action on the heart and have a merit in maintaining the coronary perfusion pressure.

Animals↗
PubMed1978

Comparison of lactate pyruvate and potassium concentration in the cardiac lymph and, arterial and coronary sinus plasma in dogs.

Lactate (LA), pyruvate (PYR) and potassium (K) concentration in the cardiac lymph were compared with those in the arterial and coronary sinus plasma in dogs. In each substance, there was a good correlation between the plasma and cardiac lymph level in the control period. In respect to LA and PYR, the concentration in the cardiac lymph correlated more with that in the arterial plasma than in the coronary sinus one. During the infusion of isoproterenol, LA and PYR in the plasma increased, while K decreased. Each substance in the cardiac lymph changed to the same degree as in the plasma in mean values. Good correlation was also observed between the arterial plasma and cardiac lymph level during the administration of the agent. However, there was no correlation of PYR between the coronary sinus plasma and the cardiac lymph. During the administration of dipyridamole LA in the coronary sinus plasma increased and that in the arterial plasma decreased. LA in the cardiac lymph did decrease as in the arterial plasma. It is concluded that the concentrations of LA, PYR and K in the cardiac lymph can be changed depending upon changes in those in the plasma and the former two parameters seem to change depending upon those in the arterial plasma rather than the coronary sinus one.

Animals↗
PubMed1977

Activation of afferent cardiac sympathetic nerve fibers of the cat by pain producing substances and by noxious heat.

Afferent discharges of 64 single units were recorded from the left cardiac sympathetic nerve of anesthetized cats. Mechano-sensitive terminals of the afferent fibers were localized in the extrapulmonary part of the pulmonary artery, left atrium, left ventricle and left pericardium, as determined by direct mechanical probing of the heart after death of the animals. Conduction velocity of the fibers ranged from 2.5 to 14.6 m/s. Excitation of these Adelta-fibers with mechanically excitable endings was produced by intravenous injections of acetylcholine, 5-hydroxytryptamine, bradykinin, histamine and veratridine, and/or by topical application of these agents to the receptor region. Noxious heat to the mechanically excitable field in the wall of the pulmonary artery and the left ventricle also activated their afferent fibers. These observations provide evidence for a certain number of afferent units in the cardiac sympathetic nerve with polymodal sensitivity. These afferent fibers can provide the spinal cord with information not only on mechanical changes in cardiac events, but also changes in the chemical environment of the cardiac nerve ending, possibly produced by myocardial ischemia.

Acetylcholine↗
PubMed1977

Effects of increased cardiac mechanical performances on flow rates of cardiac lymph in dogs.

Relationship between flow rates of cardiac lymph (LF), and coronary blood flow (CF), coronary perfusion pressure (PP), left ventricular peak systolic pressure (LVSP) and heart rate (HR) was studied in open-chest dogs. Intra-coronary administration of catecholamines (CA) and electrical stimulation of the cardiac sympathetic nerve (ES) increased LF transiently with a concomitant rise in the cardiac mechanical performance, while dipyridamole induced no change in LF in spite of a marked increase in CF. Isoproterenol at does of 0.3 and 3x10(8) g/kg induced an increasein LF to 119 +/- 4 and 167 +/- 20% (mean +/- SE); norepinephrine, 0.3 and 3 X 10(7) g/kg, to 118 +/- r and 141 +/- 13%; ES AT 5 and 20 Hz, to 135 +/- 11 and 167 +/- 10%, respectively. Peak responses of LF correlated with changes in LVSP (R = 0.59, N l1,P less than 0.001), CF Tr = 0.53, n = 51, P less than 0.001), PP (r = 0.49, n = 51, P less than 0.001) but not with changes in HR (r = 0.27, n = 51, 0.05 less than P less than 0.10). Cardiac pacing also showed a poor correlation between the changes in LF and HR under the same LVSP within the changes in HR up to 134% of control value (r = -0.12, n = 17, P GREATER THAN 0.50). It is concluded that LF is independent of changes in HR, and increased LF after CA or ES may be caused mainly by an augmented propulsive force.

Animals↗
PubMed1977

Effects of dihydroergotamine methanesulfonate on the microcirculation of the rat cremaster muscle.

Effects of dihydroergotamine on the microcirculation of the rat cremaster muscle were investigated microscopically using colour photographic technique. 1. Dihydroergotamine 10(-4) g/ml constricted arterioles of the rat cremaster. 2. Dihydroergotamine 10(-4) g/ml produced a significant contraction of venules. 3. Dihydroergotamine 10(-4) g/ml markedly inhibited the contractile response of noradrenaline 10(-6) g/ml on arterioles of the rat cremaster. The results suggest that dihydroergotamine has an appreciable vasoconstrictive action, especially upon venules, and that dihydroergotamine also has an adrenergic alpha-receptor blocking action. By means of highly sensitive negative colour film we obtained a satisfactory photograph of the rat cremaster's circulation.

Animals↗
PubMed1977

Electrical activity of sinoatrial node cells of the rabbit surviving a long exposure to cold Tyrode's solution.

The right atrium including the sinoatrial node was excised from the rabbit heart, immersed in Tyrode's solution, and kept at 0-3 degrees C for several days. The tissue then was warmed to 36-37 degrees C in well oxygenated Tyrode's solution. Transmembrane potentials from cells in the sinoatrial node region and the right atrium were recorded with microelectrodes. After 3 days of storage, the maximum diastolic potential of cells in the sinoatrial node region decreased, but the configuration of the action potential was identical to that of the pacemaker pacemaker potential in the fresh preparation. After 5-7 days of storage, the sinoatrial node tissues in some preparations showed well preserved membrane potentials and pacemaker activity, while in others, the cells were electrically quiescent, or showed subthreshold oscillatory potentials of low amplitude. Transmembrane potentials could not be recorded from the right atrial tissue after storage for this period. Sinoatrial node action potentials with normal configuration were recorded from preparations stored for longer than 10 days. The sinoatrial cells in these preparations responded well to norepinephrine and acetylcholine, indicating that the reactivity of receptors was well preserved. The results provide electrophysiological evidence that cells in the sinoatrial node region can withstand long exposure to cold and retain their sensitivity to neuromediator action, but atrial myocardial cells cannot.

Acetylcholine↗