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Biomedical subjects

K Saegusa

Publications and source records attributed to K Saegusa.

At least 19 recordsLinked to original sources
PubMed1995

[Continuous monitoring of arterial blood oxygen saturation with a pulse oximeter during spinal anesthesia].

The arterial oxygen saturation was continuously monitored in 50 patients under spinal anesthesia. Of the 50 patients, low oxygen saturation below 95% and/or its decrease of more than 5% was observed in 19 patients (38%). The remaining 31 patients (62%) showed a normal oxygen saturation. Pentazocine 0.5 mg.kg-1 i.v. correlated significantly with arterial oxygen desaturation (P = 0.0001). It is possible that laparotomy is associated with the desaturation (P = 0.0582). No correlation between desaturation and the other factors (level of analgesia, position during operation, and hydroxyzine premedication) was found.

Adolescent↗
PubMed1992

Comparison of Indium-111-labeled leukocyte scintigraphy and Technetium-99m joint scintigraphy in rheumatoid arthritis and osteoarthritis.

This study was undertaken to evaluate the use of Indium-111-labeled leukocyte (111In-WBC) imaging compared with Technetium-99m pertechnetate (99mTcO4-) imaging in 19 patients with rheumatoid arthritis (RA) and 8 with osteoarthritis. Knee and wrist joints were evaluated for both radionuclides. The results indicated a good correlation of the clinical assessment of pain and swelling with joint uptake ratio (JUR) between 111In-WBC and 99mTcO4- in RA and osteoarthritis patients. We observed a discrepancy in both imagings in "burned out" cases. It was concluded that a JUR of 111In-WBC could distinguish active RA from inactive RA or osteoarthritis at a value of 1.15 and that the use of 111In-WBC was a more reliable procedure than 99mTcO4-.

Adult↗
PubMed1992

Tyraminelike action of succinylcholine in the isolated, blood-perfused canine atrium.

The mechanisms of succinylcholine-induced cardiac effects have not been fully elucidated. Accordingly, we studied the effects of succinylcholine on atrial rate and contractile force in the isolated canine atrium perfused with donor blood. The sinus node artery was perfused with heparinized blood from the common carotid artery of the donor dog at a constant pressure of 100 mm Hg. When succinylcholine in a dose range of 30-1000 micrograms was injected directly into the sinus node artery of the isolated atrium, increases in atrial rate and contractile force were observed in a dose-related manner. The atrial rate and contractile force were increased to 10.5% +/- 1.8% (mean +/- SEM) and 56.8% +/- 8.5% above the control values after the administration of 1000 micrograms of succinylcholine, respectively. After treatment with propranolol, the positive chronotropic and inotropic effects of succinylcholine and norepinephrine were significantly suppressed. Hexamethonium or tetrodotoxin pretreatment inhibited the cardiac effects of nicotine but did not modify the succinylcholine-induced cardiac effects. The succinylcholine-induced effects were significantly inhibited by treatment with imipramine, which also suppressed the tyramine-induced effects. We conclude that succinylcholine has cardioexcitatory properties mediated by release of catecholamine due to a tyraminelike action.

Animals↗
PubMed1991

Anti-nicotinic and anti-muscarinic actions of eperisone in the isolated canine atrium.

The effects of eperisone, an antispastic agent, on the chronotropic and inotropic responses to acetylcholine, nicotine or stimulation of intracardiac autonomic nerves were evaluated in isolated, blood-perfused canine atrium. Eperisone (10-300 micrograms) injected into the sinus node artery of the isolated atrium produced dose-related negative chronotropic and inotropic effects, which were not affected by atropine. In the same doses, eperisone inhibited the negative chronotropic and inotropic responses to an injection of acetylcholine and intracardiac parasympathetic stimulation. Eperisone also suppressed the negative followed by positive cardiac responses to nicotine, but did not modify the positive responses to intracardiac sympathetic stimulation or norepinephrine. The inhibitory effect persisted much longer for the responses to nicotine or parasympathetic stimulation than for those to acetylcholine. These results suggest that eperisone at doses that induce direct cardiac depressant effects exerts its blocking action on nicotinic receptors at parasympathetic ganglia and sympathetic nerve terminals and on muscarinic receptors at the effector cells in the dog heart.

Acetylcholine↗
PubMed1990

[Gamma-ray spectra of 201Tl-radiopharmaceuticals with a scintillation camera--crosstalk of contaminating nuclides of 200Tl and/or 202Tl onto 201Tl-photopeaks].

In cardiac imaging with 201Tl, the collimator for low energy high resolution is generally used, and also the energy window, which is set on the spectral display of a pulse height analyzer of a scintillation camera, is chosen 70 +/- 12.5 keV. The purpose of this study is to discuss those conditions in 201Tl imaging with the scintillation camera. Two types of collimators for HR (high resolution) and ME (medium energy) were used in this experiment, and we measured the pulse height spectra of 201TlCl radiopharmaceuticals in air and in a cuboid phantom, connecting a multi-channel pulse height analyzer to the scintillation camera. As a result of measuring of the pulse height spectra, two different energies of gamma rays which are not supposed to emit from 201Tl nuclide were observed, and we also identified the presence of a small amount of 202Tl (with 439 keV) and/or 200Tl (with 368 keV) from their half-life measurements. Thus, the use of the HR-collimator with 201Tl imaging is not suitable, because the shielding effects of its septa is poor to 439 keV gamma-rays, and the scattered radiation produced by the Compton interaction contributes to the principal photopeak on the pulse height spectrum. Here, we recommend the use ME-collimator instead of the HR-one, and of the window width of 76 +/- 25 keV for increasing the count rate.

Humans↗
PubMed1989

Differential vagal inhibition of the positive chronotropic and inotropic responses to cardiotonics in the isolated dog atrium.

The effects of vagal nerve stimulation on the chronotropic and inotropic responses to norepinephrine (NE), dobutamine, forskolin, 3-isobutyl-1-methylxanthine (IBMX) and Bay k 8644 were investigated in the isolated, blood-perfused right atrium of the dog. Electrical stimulation of intramural vagal nerves evoked decreases in the sinus rate and atrial contractile force, which were maintained at almost constant levels during stimulation. Vagal stimulation consistently attenuated both the positive chronotropic and inotropic responses to NE, dobutamine, forskolin and IBMX. The vagal inhibition of the chronotropic response to each substance was greater than that of the inotropic one except that to Bay k 8644. Vagal stimulation did not depress the positive chronotropic and inotropic responses to Bay k 8644. These results, therefore, suggest that, under parasympathetic tonic conditions, NE, dobutamine, forskolin and IBMX induce a positive chronotropic effect much less than a positive inotropic effect in the isolated dog atrium. Our results also suggest that the vagal inhibition of the chronotropic response to a beta-adrenoceptor agonist is induced at intracellular sites in the cyclic AMP cascade proximal to the Ca channel activation and also at a site proximal to the catalytic unit of adenylate cyclase.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Operation for the stiff elbow.

Forty two cases of stiff elbow were treated by operation. Thirty three were subsequent to trauma, seven were due to ectopic ossification after quadriplegia, and two were associated with massive ectopic ossification after long term coma following head injury. Two separate skin incisions, postero-medial or medial and anterior, were used in most cases. In the post-traumatic cases, scarred, thickened posterior oblique fibres of the medial collateral ligament were usually found. Ectopic ossification was frequently situated on the postero-medial aspect of the stiff elbows. Resection of the thickened fibres or the ectopic ossification was the most effective procedure to improve elbow flexion. The average improvement in range of motion was 59 degrees in post-traumatic cases, 72 degrees in ectopic ossification after quadriplegia and 127 degrees in ectopic ossification following coma.

Adolescent↗
PubMed1989

[Comparison of SPECT images with four kinds of 99mTc collimators].

Performance of SPECT imaging systems which use a rotating gamma camera, are affected by characteristics of the detector-collimator assembly, the data acquisition method, and the filter used in image reconstruction. The purpose of this study is to examine image qualities of SPECT with different types of low energy collimators. The SPECT imaging system in this study is a rotating gamma camera ZLC-7500 (Siemens) and a data processing unit Scintipac-700 (Shimadzu). The four types of collimators compared are UHR (ultra high resolution), HR (high resolution), AP (general all purpose), and HS (high sensitivity), with 0.27, 0.66, 1.00, and 2.06 relative sensitivity, respectively. In the case of the same collimator, the spatial resolutions measured in the slice plane showed a slight difference in the FWHM values (mean values of UHR, HR, AP, and HS were 11.3 mm, 13.6 mm, 15.8 mm, and 20.4 mm, respectively.) between the center and the circumference of the field of view, in the radial direction, but a large difference in the tangential direction, with lower FWHM values (values of UHR, HR, AP, and HS were 8.4 mm, 8.7 mm, 9.3 mm, and 10.8 mm at 12 cm from the center, respectively.). In comparison of SPECT images with the four types of collimators, except for the HS collimator, image qualities of UHR, HR, and AP collimators showed only a slight difference. From the pont of view of sensitivity and spatial resolution of the collimator, it is expected that the AP collimator would be suitable for SPeCT imaging with 99mTc.

Models, Structural↗
PubMed1988

Cardiovascular effects of dibutyryl cyclic AMP in the intact dog heart and the isolated cross-perfused right atrium.

This study used an isolated right atrial preparation, cross-perfused with arterial blood from a support dog. We investigated the effects of dibutyryl cyclic AMP (DBcAMP) on heart rate and arterial blood pressure of the support dog and on the sinus rate and atrial contractile force of the isolated perfused atrium. DBcAMP was injected into the external jugular vein of the support dog or into the sinus node artery of the isolated atrium. DBcAMP to the support dog induced a small increase and/or decrease in arterial blood pressure at a dose of 3 or 10 mg/Kg i.v. It produced a decrease, with or without an increase in blood pressure, at a dose of 30 mg/Kg i.v., and a dose-dependent increase in heart rate in the support dog. In the isolated atrium, positive chronotropic and inotropic effects were observed. Direct injection of DBcAMP (3-30 mg) into the sinus node artery of the isolated atrium induced positive chronotropic and inotropic effects, after initial brief negative effects, in a dose-dependent manner. DBcAMP did not change norepinephrine-induced positive chronotropic and inotropic effects in the isolated atrium. These results demonstrate that DBcAMP induces a decrease in systemic arterial blood pressure with increases in sinus rate and atrial contractile force, and acts additively with the norepinephrine-induced positive cardiac effects in the dog heart.

Animals↗
PubMed1988

Chronotropic and inotropic effects of a new angiotensin converting enzyme inhibitor, MC-838 (altiopril calcium), on the dog heart.

The effects of calcium (-)-N-[(S)-3(N-cyclohexylcarbonyl-D-alanyl)-thio]-2-methylpropion] -L- prolinate (MC-838, altiopril calcium), an inhibitor of angiotensin converting enzyme, were investigated in 9 isolated atrial preparations and 7 intact anesthetized donor dogs. In 7 intact dogs, 1-10 mg/Kg of MC-838 caused a decrease in systemic blood pressure, but no significant influence on heart rate was observed. At the same time, in isolated atria perfused with donor's blood, significant increases in developed tension and slight increases in sinus rate were observed with 3 and 10 mg/Kg of MC-838. Intraarterial MC-838 at 10-300 micrograms did not induce significant cardiac effects and MC-838 at 1-3 mg caused an increase in developed tension and a slight increase in sinus rate. The positive inotropic and chronotropic effects were not blocked by adequate doses of propranolol, which significantly blocked norepinephrine-induced positive chronotropic and inotropic effects. It is concluded that a large amount of MC-838 has slight cardiotonic properties which are not mediated via a beta-adrenergic mechanism.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Fade responses at neuroeffector junction to vagal stimulation in the isolated, blood-perfused dog atrium.

Effects of physostigmine and of beating rate on the negative chronotropic and inotropic responses to tonic intramural parasympathetic nerve stimulation at a frequency of 5 Hz for 2 min were investigated, using the isolated, blood-perfused dog atrium which was pretreated with propranolol. The responses to stimulation reached a maximum, and then "faded" back toward the control levels during stimulation. Before physostigmine, the fade of the inotropic response was consistently observed but the fade of the chronotropic response was minimal. Both the maximum effect and the fade of the chronotropic response were augmented dose-dependently by physostigmine in spontaneously beating atria. Physostigmine increased the maximum chronotropic response to infusion of acetylcholine (ACh) but did not potentiate the fade response. These results suggest that the potentiation of the fade of the chronotropic response to stimulation after physostigmine is due to decreases in the amount of ACh at the neuroeffector junction. The maximum negative inotropic responses were dose-dependently potentiated similarly by physostigmine in isolated spontaneously beating or paced atria. The fade of the inotropic response in spontaneously beating atria was decreased along with reduction of the rate by physostigmine, whereas the fades in paced atria at 2 and 3 Hz were not changed, showing that decreases in rate during stimulation influenced the reduction of the fade. Increases in contractile force induced by infusion of CaCl2 did not alter the maximum and fade responses to stimulation in 2 Hz paced atria. The blood flow into an isolated atrium was not changed detectably during stimulation. These results suggest that the fade of the inotropic response to parasympathetic nerve stimulation is related subsidiarily to acetylcholinesterase or washout of ACh at the neuroeffector junction in isolated perfused atria.

Acetylcholine↗
PubMed1987

Time dependent impairment of vagally mediated inhibition of noradrenaline release in the dog heart.

The effects of right vagal nerve stimulation on changes in heart rate, mean coronary sinus blood flow, and noradrenaline overflow rate induced by right cardiac sympathetic nerve stimulation were investigated in anaesthetised decentralised, open chest dogs, when autonomic nerve fibres were stimulated tonically at a frequency of 4 or 5 Hz for 2.5 min. Sympathetic nerve stimulation produced a mean(SEM) increase in each of the variables (50(7.0)% in heart rate, 48(6.3)% in coronary sinus blood flow, and 87.0(12.3) ng.min-1 in noradrenaline overflow rate into coronary sinus blood at 30 s), and the increments remained almost constant during continued stimulation. Vagal nerve stimulation induced a decrease of 34(3.4)% in heart rate and of 22(4.5)% in coronary sinus blood flow and a slight reduction (-9(3.2) ng.min-1) in noradrenaline overflow rate at 30 s. Only the decrease in heart rate faded slightly with time. Combined stimulation of the sympathetic and parasympathetic nerves induced a decrease of 19(5.0)% in heart rate and 4(7.5)% in coronary sinus blood flow and an increase of 34.3(12.0) ng.min-1 in noradrenaline overflow rate at 30 s. The decrease in heart rate and coronary sinus blood flow faded, and noradrenaline overflow rate increased significantly to 86.4(17.3) ng.min-1 at 120 s. The temporal changes in heart rate, coronary sinus blood flow, and noradrenaline overflow rate caused by combined nerve stimulation were readily inhibited by treatment with atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Cardiovascular responses to a newly developed cardiotonic agent, ZSY-39 [4-methyl-5-(4-pyridinyl)-thiazole-2-carboxyamide] in dog cross-circulated atrial and ventricular preparations.

The cardiovascular effects of ZSY-39 [4-methyl-5-(4-pyridinyl)-thiazole-2-carboxyamide] were investigated in isolated and blood-perfused atrial and ventricular muscles perfused with donor's arterial blood. When ZSY-39 was given i.v. to the intact donor dog, hypotension with a slight tachycardia was induced at a dose range of 30-1,000 micrograms/kg. At the same time, slight positive chronotropic and inotropic responses appeared in isolated, perfused atria at i.v. doses of 300 and 1,000 micrograms/kg ZSY-39, indicating a relatively dominant inotropic action. Direct injection of ZSY-39 into the cannulated sinus node artery of the isolated atrium produced positive chronotropic and inotropic responses in a dose-related manner (1 to 300 micrograms). ZSY-39 also induced a dose-dependent increase in developed tension in the isolated ventricle. The positive chronotropic and inotropic effects of ZSY-39 were not modified by an adequate dose of propranolol which completely blocked norepinephrine-induced positive chronotropic and inotropic responses. From these results, it is concluded that ZSY-39 has mild cardiotonic properties, showing relatively selective positive inotropic activity.

Animals↗
PubMed1987

Cardiovascular effects of a new phenoxyalkylamine derivative, 2-isopropyl-5-[3-(2-methoxyphenoxy)propylamino]-2-(3,4,5-trimethoxy phenyl) valeronitrile fumarate (HV-525), in cross-circulated dog atrial preparations.

A newly developed phenoxyalkylamine derivative, 2-isopropyl-5-[3-(2-methoxyphenoxy)propylamino]-2-(3,4, 5-trimethoxyphenyl)-valeronitrile fumarate (HV-525), was investigated in intact dogs and in isolated dog atria perfused with anesthetized donor dog's arterial blood. When 0.3 mg/kg of HV-525 was intravenously administered to the donor dog, a depressor effect without significant changes in heart rate was observed in donor dogs and a decrease in developed tension was observed in the isolated atrium. At 1 mg/kg, HV-525 caused a depressor response in donor dogs and decreases in developed tension and atrial rate in isolated atria. The decrease in systemic blood pressure seen following 1 mg/kg of HV-525 was between 15-40 mmHg. These effects continued for about 60 min. When HV-525 was administered into the cannulated sinus node artery of the isolated atrium, dose related negative inotropic and chronotropic actions were observed. Occasionally, HV-525 induced slight, brief positive chronotropic and inotropic effects followed by long-lasting negative effects. The threshold dose for inducing the negative chronotropic effect was approximately 3 micrograms while the negative inotropic one was approximately 1 microgram. A large dose of 100 micrograms of HV-525 caused a profound deceleration but not atrial arrest. The order of potencies for inducing a negative chronotropic effect in dog atria was verapamil greater than propranolol much greater than HV-525 greater than or equal to lidocaine greater than or equal to quinidine greater than phenytoin greater than disopyramide greater than procainamide, and that for inducing a negative inotropic effect was verapamil greater than or equal to propranolol greater than HV-525 greater than lidocaine greater than phenytoin greater than disopyramide greater than procainamide greater than or equal to quinidine. HV-525 did not induce a significant effect on sinoatrial conduction time. HV-525 at the doses studied, uniformly suppressed the frequency-force relationship, while verapamil, one of the phenoxyalkylamine derivatives, caused a marked depression of high frequency-induced contraction. Thus, it is concluded that HV-525 has mild depressant properties on the cardiovascular system and may have characteristics different from those of verapamil.

Animals↗
PubMed1987

Cardiac effects of piretanide and furosemide on intact anesthetized dogs and on isolated atria.

The effects of piretanide and furosemide on systemic arterial blood pressure and heart rate were examined in the anesthetized dog and the effects on atrial rate and contractile force were assessed in isolated atrial muscle perfused with heparinized arterial blood from a donor dog. When piretanide was administered intravenously to intact dogs, the depressor and bradycardic responses were produced dose-dependently. There were no significant simultaneous chronotropic or inotropic changes in the isolated atrium. On the other hand, furosemide (1-3 mg/kg) did not induce significant changes in either systemic blood pressure or heart rate in the intact dog. The atrial rate and developed tension were also not affected in the isolated atrium. A potent beta-adrenoceptor blocking agent, propranolol (1 mg/kg i.v.), consistently produced a significant depressor response and a profound negative chronotropic effect in the intact dogs; significant negative chronotropic and inotropic effects were also observed in the isolated atrium. When large doses of piretanide and furosemide were injected intraarterially into the sinus node artery of the isolated atrium, atropine-insensitive negative chronotropic and inotropic effects were induced dose-dependently. The potency of the negative chronotropic effect of piretanide was slightly greater than that of furosemide, but the negative inotropic effect of piretanide was slightly smaller than that of furosemide. These data indicate that piretanide has a depressor effect without significant cardiac influences. However, a high dose of piretanide has negative chronotropic and inotropic effects. These effects were not observed with the doses of furosemide (1-3 mg/kg) employed in this study.

Animals↗
PubMed1987

Effects of DJ-7141, a new alpha-2 agonist, 2-(2-chloro-6-fluorophenyl)-2,3,5,6-tetra-hydro-1H-imidazo[1,2-a] imidazole hydrochloride, on the isolated atrium, cross-perfused with blood from a support dog.

The effects of DJ-7141, a new alpha-2 agonist, on an isolated atrial preparation cross-perfused with arterial blood from a support dog were investigated. In the isolated atrium, a selective injection of DJ-7141 (1-100 micrograms) into the sinus node artery induced dose-dependent positive chronotropic and inotropic effects. The positive cardiac effects of DJ-7141 were not only inhibited by propranolol and by imipramine, but reversed to negative effects, whereas the positive cardiac effects of norepinephrine were blocked by propranolol and potentiated by imipramine. Tetrodotoxin (TTX) did not modify the cardiac responses to DJ-7141. After propranolol treatment, the negative chronotropic and inotropic responses to DJ-7141 were not influenced by atropine, which completely blocked acetylcholine-induced cardiac responses. When DJ-7141 was injected into the support dog at a dose of 10-300 micrograms/Kg i.v., it induced a brief increase in femoral arterial blood pressure and a long-lasting decrease in heart rate in the support dog and increases in atrial rate and contractile force in the isolated atrium. These results suggest that the new alpha-2 agonist, DJ-7141, induces indirect positive chronotropic and inotropic effects due to a tyramine-like action and direct negative cardiac effects in the isolated dog heart, and that the tyramine-like effect may be partially responsible for the increase in blood pressure seen with DJ-7141 in in situ dogs.

Adrenergic alpha-Agonists↗
PubMed1987

Pharmacologic basis of responses to midazolam in the isolated, cross-perfused, canine right atrium.

The effects of midazolam on atrial rate and contractile force in the isolated canine atrium perfused with donor blood were investigated. When midazolam in a dose range of 100-1000 micrograms was injected directly into the sinus node artery of the isolated atrium, biphasic (negative followed by positive) chronotropic and triphasic (positive, negative followed by positive) inotropic effects were induced. After propranolol or imipramine, the positive chronotropic and the secondary positive inotropic effects were significantly suppressed, but the initial positive inotropic effect was not affected. Tetrodotoxin, atropine, or R05-4864, a selective ligand for peripheral benzodiazepine binding sites, did not modify midazolam-induced effects. When midazolam in a dose of 0.1-1 mg/kg was administered intravenously to the donor dog, monophasic negative chronotropic and inotropic effects in the isolated atrium were observed but were not as prominent. We conclude that midazolam has direct cardiac inhibitory properties including catecholamine release due to a tyramine-like action.

Animals↗