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Biomedical subjects

T Kumazawa

Publications and source records attributed to T Kumazawa.

At least 343 records · Page 19Linked to original sources
PubMed1987

Fifty percent nitrous oxide depresses recovery from anoxic heart failure induced by 100% nitrous oxide.

In experiments on an isolated rate heart lung preparation, the effects of 100% oxygen, 50% nitrous oxide or air on myocardial metabolism during recovery from anoxic heart failure were evaluated with intramyocardial high energy phosphates, lactate and glycogen. A hundred percent nitrous oxide was administered until the cardiac output decreased from 30 to 20 ml/min, and then 50% nitrous oxide, air or 100% oxygen was administered. Fifty percent nitrous oxide reduced the cardiac output and caused heart failure again. The ATP level and energy charge in hearts with 50% nitrous oxide were significantly lower than those in the others. These data indicate that 50% nitrous oxide during recovery from anoxic heart failure had deleterious effects on myocardial function and metabolism.

Journal Article↗
PubMed1987

Tracheal tube cuff pressure--study on tube size and inflating gases.

The effect of nitrous oxide on the cuff pressure was studied from the following points of view. One was the size of tubes and the type of cuff. The other was the effects of different gas mixture in the cuff. The changes of the cuff pressure were investigated using four types of tubes such as the largest standard cuffed tube which could be passed through the glottis, the 1.0 mm less in I.D. standard cuffed tube, the largest profile cuffed tube, and the 1.0 mm less in I.D. profile cuffed tube. There was no difference between the profile cuffed tube groups but in the standard cuffed tube groups, the cuff pressure increased from the beginning in 1.0 mm less I.D. tube group. Air, inhalation anesthetic gas (nitrous oxide:oxygen = 3:2) and mixtured gas (inhalation anesthetic gas and air = 4:3) were used to inflate the cuff. The cuff pressure was measured at the same patients. In the group of anesthetic gas, the cuff pressure decreased and in some cases, there occurred a leakage of gas. In the group of air, the cuff pressure increased as well as experiment I. However in the group of mixtured gas, there were almost no changes in the cuff pressure. This means that if the cuff is inflated with a mixtured gas in which nitrous oxide is under the equivalent condition, the cuff pressure would not change.

Journal Article↗
PubMed1987

Effects of thiopental on cardiac energy metabolisms in postischemic reperfusion in rat.

In experiments on isolated rat heart lung preparation, the effects of thiopental on myocardial metabolisms in postischemic reperfusion were evaluated with intramyocardial high energy phosphates, lactate, pyruvate and glycogen. The release of CPK in the perfusate blood was also measured at the end of reperfusion. After 10 min perfusion, hearts were made globally ischemic for 8 min and reperfused for 12 min. Large dose of thiopental (100 microg/ml) reduced the energy charge and glycogen content. Reperfusion with an anesthetic dose of thiopental (10 microg/ml) resulted in an exacerbation of the CPK release. Protection by thiopental during ischemia was not observed and its high dose may be harmful.

Journal Article↗
PubMed1987

Simultaneous determination of catechols in thalamic slices with liquid chromatography/electrochemistry.

A method was developed for the simultaneous determination of dopamine (DA), epinephrine (E), norepinephrine (NE), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxyphenylglycol (MHPG), as well as L-3,4-dihydroxyphenylalanine (L-DOPA) with liquid chromatography (LC) using electrochemical (EC) detection. With a ODS column and a mobile phase consisting of a sodium acetate-citrate with heptasulfonic acid, this method was applied on simultaneous determination of catechols released from thalamic slices of ddY mouse. The pretreatment of the bathing medium required only centrifugation, and the supernatant was injected directly into the LCEC system. The high potassium stimulation of catecholaminergically innervated thalamic slices led to increase in the levels of DA, NE, DOPAC and MHPG, especially of NE, but not that of L-DOPA itself. In the present study, we designed to make simultaneous determination of catechols released from thalamic slices for estimation of the physiological status of catecholaminergic neuronal activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Effects of prostaglandins and other putative chemical intermediaries on the activity of canine testicular polymodal receptors studied in vitro.

An in vitro testis-superior spermatic nerve preparation was used to evaluate the effects of chemical agents applied in the bathing solution. Both directly evoked discharges and responses to algesic solutions [bradykinin (BK) 9 X 10(-8) M, hypertonic saline 616 mM and high K+ solution 60 mM] of polymodal receptors were studied. Prostaglandin (PG)-E2 (1.4 X 10(-6)-1.4 X 10(-5) M) and serotonin (5-HT) (1.1 X 10(-6) to 1.4 X 10(-4) M) had only a weak excitatory effect. However, test responses to algesic substances were regularly greatly increased by PG-E2, -I2 and 5-HT. Concentrations of PG-E2 of 1.4 X 10(-8) M or greater augmented BK responses; higher concentrations and/or longer applications were needed to enhance responses to algesic salt solutions. Effective concentrations for the PGs and 5-HT were near those reported for inflamed tissues and exudate. Aspirin (ASA) (5.5 X 10(-4) M or greater, for more than 4 min) suppressed the responses to BK but not those evoked by hypertonic saline. The ASA effect on the BK response was largely restored by an addition of PG-E2. Substance P also had a weak excitatory effect on some polymodal receptors, but no significant enhancement of the response to BK was noted. These results further support a role of polymodal receptors in transmitting nociceptive information, of inflammatory origin.

Animals↗
PubMed1987

Respiratory depression caused by either morphine microinjection or repetitive electrical stimulation in the region of the nucleus parabrachialis of cats.

In chloralose-urethane anesthetized, vagotomized, paralyzed and artificially ventilated cats, respiratory response to either repetitive electrical stimulation or microinjection of morphine in the rostral pons was studied by recording the phrenic nerve discharges. In the region of the nucleus parabrachialis (PBN) and its ventral reticular formation, electrical stimulation delivered in 20 successive expiratory periods caused the respiratory depression to last long after the termination of stimulation. This respiratory-depressant effect could be reversed by naloxone. By a single electrical stimulation delivered in most of these effective sites, a phasic phrenic excitation was consistently elicited in the period of both expiration and inspiration, and the reduction in expiratory duration could be observed when the stimulation was delivered in expiratory period. In the microinjection study of 2.66 nmol morphine in 0.1 microliter in the localized area of the dorsolateral portion of the PBN, a significant reduction in both respiratory outputs and the rate of increase in inspiratory activity could be induced within 1 min after the application. The respiratory depression thus caused by both methods was quite similar in several respiratory variables. Thus an involvement of the PBN region in long-lasting respiratory modulation mediated by endogenous opioid system is suggested.

Animals↗
PubMed1987

Thermally potentiated responses to algesic substances of visceral nociceptors.

Using spermatic nerve preparations from testis superior, the effects of temperature rise on chemical responses were studied in vitro, within both subthreshold and suprathreshold ranges for testicular polymodal receptors, one type of visceral nociceptor. In the range of temperature subthreshold for polymodal receptors, the responses to algesic substances tested were greater at higher temperatures. The mean discharge rates induced by various concentrations of bradykinin (BK, 9 X 10(-9)-9 X 10(-6) M), were significantly greater at 36 degrees C than at 30 degrees C. Responses to hypertonic saline, tested in the temperature range, 34-43 degrees C, showed similar temperature-dependent increases, and Q10 values between 2.3 and 4.2. In the units exhibiting 'heat sensitization' with repeated testing of suprathreshold temperature rises, the response to hypertonic saline (616 mM) at 34 degrees C also increased. Although calor in the inflamed tissues is in itself not high enough to cause excitation of 'pain receptors,' temperature-dependent augmentation of chemical responses of the polymodal receptor might partly explain peripheral hyperalgesic behaviour observable in inflamed tissue on the basis of sensory receptor activity.

Animals↗
PubMed1987

Occurrence of polyamine oxidase in tissues of the catfish.

1. Polyamine oxidase (PAO) activity was found in the brain, intestine, kidney and liver of the siluroid catfish using N1-acetylspermine as substrate. It was highest in the intestine and lowest in the brain. 2. Substrate specificity of the enzyme was tested in the intestine and liver and the highest activity was found with N1-acetylspermine, followed by N1-acetylspermidine and N1,N12-diacetylspermine. 3. The apparent Km values for N1-acetylspermine were 19.6 and 46.9 microM for the intestine and liver, respectively. 4. These results suggest the presence of a system of polyamine reutilization after their acetylation in fishes.

Animals↗
PubMed1987

Effects of halothane and enflurane on myocardial metabolism during postischaemic reperfusion in the rat.

In experiments on isolated rat heart-lung preparation, the effects of halothane and enflurane on myocardial metabolism during postischaemic reperfusion were evaluated with intramyocardial high energy phosphates, lactate and glycogen. Hearts were perfused for 10 min initially and made globally ischaemic for 8 min. Afterwards, they were reperfused for 12 min. Halothane or enflurane was administered from 5 min after the start of perfusion to the end of reperfusion. There were no significant differences in contents of high energy phosphates between control (C), halothane (H) and enflurane (E) groups (ATP: 15.50 +/- 0.87, 16.05 +/- 1.99 and 15.16 +/- 2.03 mumol/g dry wt, respectively). However, lactate levels in the hearts in Groups H and E were significantly higher than those in Group C (44.04 +/- 10.54, 40.63 +/- 10.34 vs 28.63 +/- 5.98). Slight deterioration in the myocardial oxidation-reduction state may be caused by inhalational anaesthetics when they are administered during the postischaemic reperfusion period.

Anesthesia, General↗
PubMed1987

Response properties of polymodal receptors studied using in vitro testis superior spermatic nerve preparations of dogs.

Characteristics of the polymodal receptor were studied using in vitro testis superior spermatic nerve preparations excised from anesthetized dogs. They were in most aspects similar to those reported previously using in vivo preparations. The majority (90%) of the tested polymodal units had small myelinated nerve fibers; the rest had nonmyelinated fibers. The mean mechanical threshold as determined by von Frey hairs was 17.5 g/mm2 (n = 476). There was a tendency for a unit with a higher conduction velocity to have a lower mechanical threshold. Bradykinin and hypertonic saline consistently caused a dose-dependent increase in discharge rate of these units; high K+ solution was also found to be a consistent stimulant. The responses of C-fiber receptors were not significantly different from those of A-delta-fibers. Heat stimulation up to 50 degrees C evoked discharges in 99 out of the total 103 units tested. The mean threshold temperature was 44.4 degrees C for the first trial. In 19 units in which the same heat stimulation was tested after an interval of 10 min, 10 units showed sensitization; 3 units were deactivated; and no clear difference was observed in the rest. No unit responded with a substantial increase in discharge rate to cold stimuli of 20 degrees C or less. A small temperature rise of 2 degrees C from the normal surface temperature of the testis (34 degrees C) significantly increased the response to hypertonic saline (616 mM) (2.41 +/- 0.22 impulses/s at 34 degrees C to 3.23 +/- 0.44 impulses/s at 36 degrees C) and to bradykinin (9 X 10(-8) M) (1.95 +/- 0.35 impulses/s at 34 degrees C to 2.85 +/- 0.19 impulses/s at 36 degrees C). The majority of the units recorded from the superior spermatic nerve in this experiment were most probably of polymodal receptor type, although the heat response was tested in a limited number of units. A very small number of a different type of receptor was discovered: rapidly adapting mechano-receptors, which responded almost exclusively to mechanical stimulation and were especially sensitive to a light mechanical stimulus moving across the receptive fields. The response properties of receptors studied in vitro remained practically unchanged during the experiments of several hours. The present experiments have shown that this preparation is suitable for systematic investigations, especially of the effects of chemical agents, on the polymodal receptor, which plays important roles in nociceptive functions.

Adaptation, Physiological↗
PubMed1987

Quantitative immunoelectron microscopic localization of (Na+,K+)ATPase in rat parotid gland.

Distribution of (Na+,K+)ATPase on the cell membranes of acinar and duct cells of rat parotid gland was investigated quantitatively by immunoelectron microscopy using the post-embedding protein A-gold technique. In acinar cells, ATPase was localized predominantly on the basolateral plasma membranes. A small but significant amount of (Na+,K+)ATPase was, however, detected on the luminal plasma membranes, especially on the microvillar region of the acinar cells; the surface density on the luminal membrane was approximately one third of that on the basolateral membranes. In duct cells, many gold particles were found on the basolateral membrane, especially along the basal infoldings of the plasma membranes, whereas no significant gold particles were found on the luminal plasma membranes, suggesting unilateral distribution of ATPase in duct cells. We suggest that in acinar cells sodium ion is not only transported paracellularly but is also actively transported intracellularly into the luminal space by the (Na+,K+)ATPase located on the luminal plasma membranes, and that water is passively transported to the luminal space to form a plasma-like isotonic primary saliva, while in the duct cells the same ion is selectively re-absorbed intracellularly by (Na+,K+)ATPase found in abundance along the many infoldings of the basal plasma membranes, thus producing the hypotonic saliva.

Animals↗
PubMed1987

Protective effects of superoxide dismutase against oxygen toxicity in rat's heart lung preparation.

Oxygen toxicity in the non-ischemic and non-hypoxic heart has not been reported. In an experiment on isolated rat heart lung preparation, the effects of superoxide dismutase (SOD) on oxygen toxicity during hyperoxic perfusion were evaluated with intramyocardial high energy phosphates and the release of creatine phosphokinase (CPK) in the perfusate blood. Although there were no significant differences in high energy phosphates between SOD-treated and untreated hearts, the CPK release from the SOD-treated hearts was significantly less than from the untreated hearts. SOD increased the oxygen pressure of perfusate blood, too. These results indicate that hyperoxia induced cardiac and lung cell damage which was protected by SOD.

Adenosine Diphosphate↗
PubMed1987

Successful pancreatic allografts in combination with bone marrow transplantation in mice.

We have established a new method for pancreatic allografts in mice by combining pancreatic transplantation with allogeneic bone marrow transplantation. In this approach, we first transplanted bone marrow to induce tolerance to both donor-type and host-type major histocompatibility complex (MHC) determinants. Pancreatic tissue from the same mouse strain as bone marrow donor was then grafted under the renal capsule. Acceptance of the grafts was confirmed by histopathological and immunohistochemical techniques. BALB/c mice reconstituted with C57BL/6J bone marrow cells accepted pancreatic tissue from both bone marrow donor (C57BL/6J)-type and host (BALB/c)-type mice. An immunohistochemical study revealed the presence of functional islets under the renal capsules. Assays for both mixed lymphocyte reaction (MLR) and induction of cytotoxic T lymphocytes indicated that the newly developed T cells are tolerant of both donor (stem cell)-type and host-type MHC determinants. By contrast, the T cells of these chimeras showed a significant responsiveness to third party MHC determinants. These findings suggest that pancreatic allografts combined with bone marrow transplantation may become a viable strategy for the treatment of patients with diabetes or patients who have undergone pancreatectomy.

Animals↗