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Biomedical subjects

M Kanno

Publications and source records attributed to M Kanno.

At least 289 records · Page 16Linked to original sources
PubMed1987

Negative inotropic effects of halothane, enflurane, and isoflurane in papillary muscles from diabetic rats.

Myocardial contractile responses to halothane, enflurane, and isoflurane were studied in papillary muscles isolated from streptozotocin-induced diabetic rats and in those from age-matched control rats. The developed tension in diabetic papillary muscles electrically paced at a constant rate was not different from that in control muscles, but both the time to peak tension and the relaxation time of the isometric contraction were significantly prolonged in diabetic muscles. Halothane, enflurane, and isoflurane all produced negative inotropic effects in both diabetic and control muscles. However, the negative inotropic effects were significantly less in the muscles from diabetic rats than in the muscles from control rats throughout the range of concentrations. In muscles from both the diabetic and control rats, the negative inotropic effects of these anesthetics were accompanied by decreases in the time to peak tension and in relaxation time. The results suggest that the myocardium from the diabetic rat is less sensitive to the negative inotropic action of volatile anesthetics than is the myocardium of normal hearts.

Animals↗
PubMed1986

Attenuation of endothelium-dependent relaxation in aorta from diabetic rats.

Endothelium-dependent relaxation was examined in aortic ring preparations obtained from rats with streptozotocin-induced diabetes. The endothelium-dependent relaxation which was produced by acetylcholine and histamine in aortic rings precontracted with norepinephrine was significantly attenuated in aortic rings from diabetic rats when compared with the relaxation in rings from age-matched control animals. However, the relaxation induced by sodium nitroprusside (an endothelium-independent relaxant agent) in diabetic preparations was comparable to the control. These results show that diabetes leads to an impairment of the endothelium-dependent relaxation of aorta.

Acetylcholine↗
PubMed1986

Electrophysiological effects of amosulalol, a new alpha- and beta-adrenoceptor blocker, in isolated rabbit papillary muscles.

The electrophysiological effects of amosulalol, a newly developed alpha- and beta-adrenoceptor blocking agent, were examined and compared with those of labetalol, prazosin and propranolol in isolated rabbit papillary muscles by means of standard microelectrode techniques. Amosulalol above 3 microM produced a concentration-dependent decrease in the maximum rate of depolarization (Vmax) and an increase in action potential duration (APD). Labetalol and prazosin produced a similar APD prolongation, and Vmax was depressed by all these drugs in a concentration-dependent manner. The depressant action of these drugs on Vmax was enhanced by increasing the stimulation rate from 0.25 to 2.0 Hz. In the presence of these drugs the Vmax declined exponentially to a new plateau level (rate-dependent block) and the onset of the rate dependent block for amosulalol at 1 Hz was similar to that for labetalol and propranolol, and faster than that for prazosin. The time constants of the recovery from rate-dependent block for amosulalol, labetalol and prazosin were considerably slower than that for propranolol. These results suggest that amosulalol possesses class I and III antiarrhythmic properties and the recovery from the rate-dependent block of Vmax is relatively slow with this drug.

Action Potentials↗
PubMed1986

Voltage-dependent effects of YC-170, a dihydropyridine calcium channel modulator, in cardiovascular tissues.

Voltage-dependent effects of YC-170, a putative calcium channel activator, were examined and compared with those of Bay K 8644 in isolated guinea-pig cardiac tissues and rabbit aortae. In guinea-pig left atria superfused with a normal bathing solution (4 mmol/l K+), both YC-170 (10 mumol/l) and Bay K 8644 (1 mumol/l) produced a positive inotropic action accompanied by a prolongation of action potential durations (APDs). In normally-polarized guinea-pig papillary muscles Bay K 8644 increased force of contraction (fc) and APDs. However, YC-170 failed to increase fc in spite of a slight prolongation of APDs. In papillary muscles partially depolarized by 25 mmol/l K+ solution, Bay K 8644 enhanced the electrically-induced slow action potentials and contractile force. In contrast with Bay K 8644, YC-170 significantly depressed the slow action potentials and decreased fc. YC-170 also showed the depressant action on the slow action potentials induced by isoproterenol (0.1 mumol/l), histamine (3 mumol/l) and tetraethylammonium (10 mmol/l) plus high Ca2+ (4 mmol/l). In sinoatrial node cells of guinea-pig right atria Bay K 8644 produced a positive chronotropic action with increases in the maximum rate of rise (Vmax) and action potential amplitude (APA), whereas YC-170 produced a negative chronotropic action with decreases in Vmax and APA. In the rabbit aortic strips preincubated with bathing solution containing various concentrations of K+ (15, 20, 30 and 40 mmol/l), Bay K 8644 produced concentration-dependent contractions in a range of concentrations up to 0.3 mumol/l. However, when the concentration exceeded 1 mumol/l, Bay K 8644 caused a slight relaxation, irrespective of the K+ concentrations of bathing solution. YC-170 in concentrations of 10 and 30 mumol/l contracted the aortic strips placed in 5.9 or 15 mmol/l K+ bathing solution, but caused relaxation in 30 or 40 mmol/l K+ bathing solution. These results suggest that YC-170 is a dihydropyridine calcium channel modulator which behaves as a Ca2+ channel agonist in tissues of high membrane potentials, but as a Ca2+ channel antagonist in tissues of low membrane potentials.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1986

Sequence and expression of transcripts of the T-cell antigen receptor alpha-chain gene in a functional, antigen-specific suppressor-T-cell hybridoma.

We have detected rearrangement and expression of a gene encoding a T-cell antigen receptor alpha chain in the keyhole limpet hemocyanin (KLH)-specific, inducible suppressor-T-cell (Ts) hybridoma 34S-281 (BW5147 lymphoma-C57BL/6Ts) by using alpha-chain cDNA clones isolated from this Ts hybridoma. The cDNA clones have a restriction length polymorphism in the constant region that identifies them as being of C57BL/6 origin. The cDNA sequence has an ATG start codon for an open reading frame including variable, joining, and constant gene segments. Furthermore, the Ts alpha-chain gene transcripts were detected on membrane-bound polysomes by RNA blot analysis using a variable-region fragment from one of the alpha-chain cDNA clones as probe, suggesting that they are actively translated in the Ts hybridoma. As the beta-chain gene is deleted in all Ts hybridomas analyzed, and since a disulfide-linked dimer is detectable by two-dimensional NaDodSO4/PAGE of lysates of surface-radioiodinated Ts, we suggest that Ts antigen receptors are either alpha-chain homodimers or heterodimers composed of the alpha chain in association with an undefined chain.

Animals↗
PubMed1986

Inotropic effects of Ca2+ channel agonist and antagonists in neuraminidase-treated left atria of rats.

The effects of removal of sialic acid from cardiac sarcolemma on contractile functions and on inotropic responses to Ca2+ channel agonist and antagonists were investigated in rat left atria. About 64% of the total sialic acid content of the left atria was removed during a 90 min exposure to neuraminidase (2 u ml-1). The removal of sialic acid neither affected the development of twitch tension induced by stimulation at a frequency of 0.5 Hz, nor altered the interval-dependent changes in contractility such as the force-frequency relationship and post rest contractions. The positive inotropic effects produced by isoprenaline, and by an increase in extracellular Ca2+ concentration were the same in the neuraminidase-treated preparations as those in the untreated preparations. Bay K 8644, a Ca2+ channel agonist, induced an increase in contractility in the neuraminidase-treated preparations comparable to that in the untreated ones. Neuraminidase treatment significantly attenuated the negative inotropic effects of verapamil and diltiazem, whereas it had no effect on that of nifedipine. The results indicate that sialic acid removal modifies neither the basal contractile functions nor the positive inotropism which is associated with an enhancement of the slow inward Ca2+ current. However, sialic acid, which constitutes the glycocalyx of the cardiac sarcolemma, may be involved in the mechanism of the Ca2+ channel antagonistic actions of verapamil and diltiazem, but not that of nifedipine. Thus, our results provide pharmacological evidence that verapamil and diltiazem behave differently from the dihydropyridine compounds.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1986

[Effects of nipradilol, a new beta-blocker, and its metabolite, denitro-nipradilol, on heart rate and AV conduction in anesthetized dogs].

Effects of nipradilol, a new beta-blocker, and its metabolite, denitro-nipradilol, on heart rate and atrioventricular conduction were investigated in anesthetized dogs and were compared with those of propranolol. The beta-blocking activity of nipradilol was nearly three times as potent as that of denitro-nipradilol which was almost the same as the beta-blocking activity of propranolol. Decrease in heart rate (HR) and prolongation of the atrio-His bundle conduction time (AH) were dose-dependently produced by nipradilol (10, 30 and 100 micrograms/kg, i.v.), denitro-nipradilol (30, 100 micrograms/kg, i.v.) and propranolol (30, 100 micrograms/kg, i.v.). The functional refractory period of the atrioventricular node (AVNFRP) was also prolonged by these drugs in a dose-dependent manner. The changes in HR, AH and AVNFRP were well correlated to their beta-blocking activities. However, His bundle-ventricle conduction time (HV) was insignificantly affected by these beta-blockers in the doses mentioned above. In the reserpinized and atropinized dogs in which propranolol (100 and 300 micrograms/kg, i.v.) showed very slight, insignificant influence on HR and AH, nipradilol significantly decreased HR and prolonged AH. AVNFRP was also prolonged significantly by nipradilol. These effects of nipradilol were observed even after the administration of propranolol. Denitronipradilol also produced a decrease in HR and prolongations of AH and AVNFRP in reserpinized, atropinized and propranolol-pretreated dogs. These results indicate that nipradilol and its metabolite, denitro-nipradilol, possess a direct depressant action on the sinoatrial node and the atrioventricular node.

Adrenergic beta-Antagonists↗
PubMed1986

Vascular and cardiac effects of a new dihydropyridine derivative, YC-170: a comparison with Bay K 8644.

The pharmacological effects of YC-170, a new dihydropyridine derivative, were studied in the rabbit aortic strips and guinea pig cardiac preparations and compared with those of Bay K 8644. In the rabbit aortic strips, YC-170 produced contraction in normal physiological saline solution ([K+]0 = 5.9 mM) in a concentration-dependent manner. Increasing the [K+]0 of the medium to 15 mM enhanced the contractile response. The maximum contraction produced by YC-170 at [K+]0 of 15 mM was comparable to that by Bay K 8644. However, YC-170 induced relaxation when the strip was contracted by 60 mM K+. In guinea pig left atrium, YC-170 produced a positive inotropic effect in a concentration-dependent manner, but its extent was far less than that of Bay K 8644. Like Bay K 8644, however, YC-170 increased the time to peak tension and relaxation time of the isometric tension, and prolonged the action potential duration. YC-170 failed to produce a positive inotropic action in the papillary muscle in which Bay K 8644 was a potent positive inotropic agent. In spontaneously beating right atria, YC-170 caused a negative chronotropic effect, whereas Bay K 8644 a positive one. The positive inotropic and vasoconstrictor effects of YC-170 were antagonized competitively by a Ca++ antagonist nicardipine. When the left atria were depolarized with high-K+ medium, the positive inotropic effect of YC-170 was attenuated progressively with increasing [K+]0 and at 13.2 mM K+ a negative inotropic effect was induced by YC-170.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1986

[Clinical study of non-Hodgkin's lymphoma--results of the Kanazawa University-Kurume University Cooperative Study on Malignant Lymphomas].

Ninety-two patients with previously untreated non-Hodgkin's lymphoma (NHL) were studied multidisciplinarily. The high incidence of NHL in elderly men (older than 60 years) was confirmed. With regard to the initial site, 51 patients (55.5%) were affected in the nodal region while other patients were affected in the extranodal or Waldeyer's ring region. Eighty-two patients (89.1%) were diagnosed as having diffuse lymphoma, and 47 of these patients were further classified into large cell type (LSG classification). Surface marker analysis revealed that the incidence of B cell-type NHL was twice as high as that of T cell-type NHL. All patients were entered into a randomized trial of radiotherapy and/or combination chemotherapies (ACOP, ACOP-E and AclBEP regimens) according to clinical stage. More than 90% of the patients with early-stage NHL achieved complete remission (CR), and the CR rate for patients with advanced-stage disease was about 50%. All patients with CS I NHL are still alive at 27 months after diagnosis, and the survival rate of patients with CS II NHL at 35 months after diagnosis is 80%. However, the median survival time of patients with advanced-stage disease was estimated to be 16 months.

Adult↗
PubMed1985

Effect of Ni2+ on the multiphasic positive inotropic responses to histamine mediated by H1-receptors in left atria of guinea pigs.

Effects of calcium antagonists and Ni2+ on the positive inotropic responses to histamine mediated by H1-receptors were investigated in left atria of guinea pigs. The preparations were electrically driven at 0.5 Hz in Krebs-Henseleit solution at a temperature of 30 degrees C unless stated otherwise. Histamine in low concentrations of 10 and 100 nmol/1 produced a monophasic positive inotropic effect, whereas in concentrations higher than 1 mumol/1 it exerted a multiphasic inotropic response composed of an initial increasing phase (initial component) and a second and late developing, greater positive inotropic phase (second component). These two components were sometimes separated by a transient decrease in developed tension. Both positive inotropic components caused by 3 mumol/1 histamine were inhibited by the H1-antagonists mepyramine, D-chlorpheniramine and diphenhydramine in a concentration-dependent manner, but not by the H2-antagonist cimetidine. Pretreatment with Ni2+ in concentrations of 0.2 and 0.5 mmol/1 preferentially suppressed the second component of the inotropic effect produced by 3 mumol/1 histamine without significantly affecting the initial component. On the other hand, the monophasic positive inotropic effect of 30 nmol/1 histamine was almost unaffected by this cation. The concentration-response curves for the positive inotropic effect of histamine were hardly influenced by Ni2+ in the range of lower concentrations of histamine, but significantly suppressed in the range of higher concentrations of the agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Computed panoramic tomography with scanning laser-stimulated luminescence.

A new imaging system for the dental field that combines recent advances in both the electronics and computer technologies was developed. It is a panoramic tomography process based on the newly developed laser-scan system and an imaging system featuring (1) clear images with abundant diagnostic information and wide latitude; (2) the possibility of new diagnostic methods through image-information processing; and (3) reduction of exposure to a minimum.

Adult↗
PubMed1985

Intracellular K+ and Na+ activities under hypoxia, acidosis, and no glucose in dog hearts.

To gain a better understanding of the ionic mechanisms responsible for the electrophysiological disturbances occurring during myocardial ischemia, transmembrane potentials and intracellular potassium (aiK) and sodium (aiNa) ion activities were measured under individual and combined conditions of hypoxia (Po2 less than 50 mmHg), respiratory acidosis (pH 6.6), and no glucose in isolated epicardial ventricular muscle preparations of the canine heart using conventional and ion-selective microelectrode techniques. After 30 min superfusion with hypoxic, acidic, and glucose-free solution under 2-Hz stimulation, resting membrane potential (RMP) was significantly reduced from -85.5 +/- 0.6 to -69.5 +/- 1.0 mV, accompanied by decreases in action potential amplitude, maximum upstroke velocity of phase O, and action potential duration. aiK was significantly decreased from 101.0 +/- 5.6 to 79.5 +/- 5.8 mM, whereas aiNa was not significantly altered by the combined condition. RMP and aiK were moderately decreased by hypoxia alone, slightly decreased by acidosis, and hardly affected by the glucose-free condition. The extent of depolarization was well correlated with the decrease in aiK. These results suggest that Na+-K+ pump inhibition may not be a major cause of K+ efflux from myocardial cells under the hypoxic, acidic, and glucose-free condition and that hypoxia is the most important factor affecting aiK and RMP among these conditions.

Acidosis↗
PubMed1985

[Traumatic arteriovenous fistula of the deep temporal artery--a case report].

A rare case of traumatic AV fistula of the deep temporal artery is reported. The patient, a 33 years old male, struck his forehead and left temporal region in a traffic accident on March 30, 1983. He noticed the swelling at his temporal region 5 days after the accident as it became pulsative and enlarged. He was admitted on May 23 and left external carotid angiography revealed an AV fistula which was fed by the deep temporal artery and drained into the superficial temporal vein. The operation was performed on May 27 and showed that the AV fistula was not in the subcutaneous tissue, but buried in the temporal muscle. Total extirpation was performed. Postoperative course was uneventful and he was discharged on June 10. Microscopic examination of the AV fistula demonstrated some traumatic findings, such as tear of the wall of vein, thrombosed artery and an aneurysm-like protrusion of the wall of the artery.

Adult↗
PubMed1985

Electrophysiologic effects of enflurane and halothane on isolated rabbit hearts in the presence and absence of metabolic acidosis.

Electrophysiologic effects of halothane and enflurane in the presence of a normal pH and during metabolic acidosis were examined in isolated rabbit hearts perfused at a constant rate. During exposure to a normal pH, both halothane and enflurane produced concentration-dependent suppression of sinus node automaticity and atrioventricular conduction. Intraatrial and intraventricular conduction times during constant pacing were slightly but significantly prolonged by these anesthetics at 2 MAC. The magnitudes of these electrophysiologic changes were similar with halothane and enflurane when compared at the same MAC. These electrophysiologic effects became more marked during metabolic acidosis (pH 6.9). These results suggest that enflurane and halothane have direct depressant actions on the cardiac conduction system and that these electrophysiologic effects may be augmented by metabolic acidosis.

Acidosis↗
PubMed1984

Effects of nipradilol (K-351) on the electrophysiological properties of canine cardiac tissues: comparison with propranolol and sotalol.

The electrophysiological effects of K-351 (0.3-300 microM), a new beta-adrenoceptor blocking drug, on canine Purkinje and ventricular muscle fibers were examined and compared with those of propranolol (0.3-30 microM) and sotalol (3-300 microM) using standard microelectrode techniques. K-351 and propranolol dose dependently reduced the maximum upstroke velocity of phase 0 and action potential amplitude in both cardiac tissues. Action potential durations (APD) of Purkinje fibers were shortened by both propranolol and K-351 but prolonged by sotalol. However, in ventricular muscle fibers K-351 and sotalol significantly prolonged APD and effective refractory periods which contrasted with the unchanged APD after propranolol. These results suggest that K-351 is a beta-blocking drug possessing a membrane stabilizing action (class I antiarrhythmic properties) and in ventricular muscles it can also exert an APD-prolonging effect (class III antiarrhythmic properties).

Action Potentials↗
PubMed1984

Functional roles of two polypeptide chains that compose an antigen-specific suppressor T cell factor.

The functional roles of the two polypeptide chains that compose the T cell suppressor factor (TsF) that mediates the antigen-specific and genetically restricted suppressor function were studied by using the heavy or light chains isolated from the conventional TsF or the 11S and 13S mRNA translation products of TsF. Either the heavy or the light chain of mRNA translation products reconstitutes the active TsF that suppresses the antibody response in an antigen-specific and genetically restricted manner when it is combined with the isolated heavy or light chain from the conventional TsF. As a consequence, the antigen-binding heavy chain mediates the antigen specificity of TsF. On the other hand, the I-J-positive light chain works as an element to determine the genetic restriction specificity. Thus, the identity of the histocompatibility between the I-J haplotypes on the light chain and the responding cell is essential for the functional expression of TsF. No genetic preference, however, was observed, in the association of the heavy and light chains of TsF.

Animals↗