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T Hukuhara

Publications and source records attributed to T Hukuhara.

At least 37 records · Page 2Linked to original sources
PubMed1986

Involvement of central serotonergic mechanisms in the cough reflex.

To determine the role of central serotonergic systems in modulating the cough reflex, the effects of serotonergic agonists on the respiration and the cough reflex were comparatively studied. Male and female cats were anesthetized with sodium pentobarbital. Respiration and cough reflex were measured using a pneumotachograph via a cannula inserted into the trachea. The cough reflex was elicited by electrical stimuli to the superior laryngeal nerve. Tranylcypromine, a MAO inhibitor, in a dose of 5 mg/kg, i.v., increased the respiration, but depressed the cough reflex. The serotonin precursor 5-hydroxytryptophan (5 mg/kg, i.v.) depressed the respiration and the cough reflex. Haloperidol (2 mg/kg, i.v.) abolished the tranylcypromine-stimulated respiratory responses, and it intensified the tranylcypromine induced cough depression. It is concluded that the increase in serotonin levels in the brain has a depressant influence on the central generating mechanisms of the cough reflex. Furthermore, central dopaminergic mechanisms seem to play a modulating role on the cough reflex.

5-Hydroxytryptophan↗
PubMed1983

Effects of psychotropics on the periodic fluctuation in EEG synchronized with respiratory rhythms during cough reflex.

It is known that the psychotropics reduce the cough reflex. To clarify the relation between the higher centers and cough reflex, we investigated the psychotropics property of the respiratory periodic fluctuation in EEG during cough reflex and after administration of psychotropics. Male mongrel dogs immobilized were maintained with artificial respiration. The efferent activities of phrenic nerve and scalp EEG were recorded, and on the basis of the resulting observations, crosscorrelation coefficients were computed using a digital computer. The cough reflex was accompanied by an increase in crosscorrelation coefficient (C. C.) between EEG and phrenic nerve activities. the C. C. between EEG and phrenic nerve activities decreased after iv administration of chlorpromazine ( mg/kg), while administration of imipramine (1-3 mg/kg) and diazepam (1-3 mg/kg) increased the C. C., respectively. The increase in the C. C. observed during cough reflex was inhibited by iv administration of these three drugs. The fact that the C. C. increased during cough reflex suggested that the ascending output from respiratory center to the higher center reinforced during this period. Furthermore, it is suggested that the psychotropics inhibited the neuronal mechanisms of the brain stem that plays an important role in cough reflex by acting upon the feedback loop located between the respiratory center and the higher centers.

Animals↗
PubMed1982

Analysis of efferent discharges of the phrenic nerve during the cough reflex.

The response of the phrenic nerve activities during the cough reflex was investigated in anesthetized dogs. The phrenic nerve activities were recorded from the central cut end of the nerve. Changes in phrenic nerve activities were evaluated by means of computer analysis using the programs for power spectrum, amplitude histogram, pulse density variation, and autocorrelation. The cough reflex was induced by mechanical stimulation of the tracheal mucosa. The cough reflex evoked was accompanied by an increase in the number of spike potentials and shortening of the respiratory burst period of the phrenic nerve activities. There was a significant correlation between the intensity of expiration and the multiplication product of the mean amplitude of spike potentials and spike numbers of the phrenic nerve activities during the cough reflex. Total activity of the discharge, amplitude of spike potentials, and pulse density of the phrenic nerve activities also increased during the cough reflex, while the autocorrelation coefficient decreased. These changes were inhibited by codeine. The responses of the phrenic nerve activity during the cough reflex were also observed under artificial respiration as well as under spontaneous respiration. These findings indicate that the phrenic nerve activity can be an indicator of the cough reflex, and it is useful for the indicator to investigate the central mechanisms of the cough reflex.

Animals↗
PubMed1982

[Effects of antitussive drugs on the central respiratory mechanisms during the cough reflex].

Effects of antitussive drugs on the phrenic nerve activities during the cough reflex were investigated by means of a power spectrum analysis as a quantitative evaluation of each of the frequency band components of the phrenic nerve activities in anesthetized dogs. The efferent activities of the phrenic nerve were recorded from the central cut end of the phrenic nerve. Each fraction of the phrenic nerve activity was fractionated into bands spanning a range of 100 Hz each by a variable filter and analyzed using a program for the power spectrum analysis. The increase in power of each of the frequency band components was observed during the cough reflex induced by mechanical stimulation of the tracheal mucosa. Particularly, the power of the 2 approximately 100 Hz band components increased significantly as compared with the other frequency band components. An i.v. administration of codeine (3 mg/kg) significantly inhibited the increase in power of all frequency band components during the cough reflex. After administration of dextromethorphan (10 mg/kg, i.v.) or fominoben (8 mg/kg, i.v.), the increase in power of the 2 approximately 100 Hz band components of the phrenic nerve activity during the cough reflex was decreased significantly for 5 approximately 10 min; however, the other frequency band components were not affected. These results provide some evidence for a difference between these three antitussive drugs with respect to the mechanisms of action in the process of the central integration for the cough reflex.

Animals↗
PubMed1982

[A quantitative analysis of the phrenic nerve activities during the cough reflex].

The phrenic nerve activity is an appropriate indicator for the output of the respiratory center as a whole, although a quantitative analysis of each of the frequency band components that constitute the neural activities during the respiratory reflex has not yet been made by other investigators. In the present study, we have made a quantitative analysis of each of the frequency band components of phrenic nerve activity during the cough reflex in anesthetized dogs. The efferent activities of the phrenic nerve were recorded from the central cut end of the phrenic nerve. Each fraction of phrenic nerve activity was separated into bands spanning a range of 100 Hz each by a variable filter and analyzed using a program for the power spectrum. The cough reflex was induced by mechanical stimulation of the tracheal mucosa. In the power spectrum analysis of each frequency band, increase in the power of each of the frequency band components was observed during the cough reflex. Particularly, the power of the 2 approximately 100 Hz band components increased significant as compared with the other frequency band components. Such as increase in the power of the 2 approximately 100 Hz band components toward the other frequency band components during the cough reflex was not observed after an i.v. administration of DMPP and lobeline, but the power increased extended over every frequency band. These findings suggest that the process for integrating the cough reflex was different from that of the other respiratory reflexes and that the present method is useful for investigating the central mechanisms of the cough reflex.

Action Potentials↗
PubMed1980

The effect of intraluminal pressure upon the frequency of intestinal contraction waves.

In guinea pigs the lumen of an excised jejunal segment was perfused to study the effect of intraluminal pressure on the frequency of rhythmic contraction waves. Within the range of 0 to 40 mmH2O, increases in intraluminal pressure caused increases in the frequency of contraction waves. At pressures of 10, 15, 20, 30 and 40 mmH2O the frequency was 7.9, 9.0, 10.9, 12.5 and 13.3 per min (mean of ten preparations), respectively. An exponential relationship was proved to exist between the pressure and the frequency.

Animals↗
PubMed1976

[Role of the intramural ganglion cells played in the motility of the large intestine of the tortoise, Geoclemys reevesii].

The development of the intramural plexuses in the tortoise, Geoclemys reevesii was inferior to that observed in the fowl: the meshes of both Auerbach's and Meissner's plexuses were coarser, and consisted of less number of nerve fibers. Occasionally, a small ganglion was seen at the crossing points of the meshes. The average number of nerve cells contained in the ganglion was estimated to be 1500/cm2, being about half as much as that estimated in the fowl. When the mucosa of a colon in vitro was stimulated mechanically by stroking or chemically with 1/10 N HCl, the excitability of the colonic muscle was raised at the region oral to the stimulated spot, but lowered at the region anal to it. These effects were abolished by applying a ganglion-blocking agent, hexamethonium (10(-6) g/ml), to the mucosa. When the intraluminal pressure of a colon in vitro was raised from 0 to 3-12 cm H2O, the colon was distended at first but soon contracted powerfully. The contraction became extremely reduced or was abolished when hexamethonium (3.5X10(-7) approximately 1X10(-5) g/ml) was added to the saline solution in which the colon was immersed. The results indicate that the intramural ganglion cells serve as the center of the intrinsic mucosal reflex.

Animals↗
PubMed1975

[The role of the intramural ganglion cells taken in the ileo-colic motilities of the catfish (Parasilurus asotus) (author's transl)].

In catfishes the role of the intramural ganglion cells taken in the ileo-colic motilities were studied. The results obtained were summarized as follows: (1) When the stomach was half full of contents, the gastric peristalses recurrently occurred at the cardia, traveling caudad to come to an end at the pylorus. (2) In the duodenum contractions were produced here and there, traveling both caudad and orad, to mingle the contents with each other, respectively. (3) Along its whole length the ileum often fell in a more or less tonically contracted state, resulting in the retardation of the transfer of the duodenal contents. Furthermore, the effect described above was increased by powerful contractions which were occasionally produced here and there to travel in both directions only a short distance. (4) When the large intestine was moderately full of contents, powerful contractions produced in the caudal half of the ileum frequently traveled caudally to expel the contents out of the anus. (5) The supravital staining with methylene blue solution revealed that the myenteric plexus existed, whereas the submucous plexus did not contain the nerve cells. In the former, thick nerve bundles without forming meshworks took their course along the long axis of the intestine, accepting many finer axons coming from the nerve cells, which were not in groups, but lay sporadically, although they showed a tendency to increase their number in the area close to the nerve bundles. Any sign of the intrinsic mucosal reflex was not observed with the stimulation either of a spot (by rubbing with cotton) or of the whole surface (by raising the intraluminal pressure) of the mucosa of the intestine. These facts suggest that in catfishes the intramural ganglion cells have no function to regulate the strength as well as the direction of propagation of the contraction waves.

Animals↗
PubMed1975

[Observations on the gastrointestinal movements of the tortoise (Geoclemys reevesii) by means of the abdominal-window-technique].

In the tortoise the gastrointestinal movements were observed utilizing the abdominal-window-technique. The results obtained were summarized as follows: (1) So far as the intestine was exposed to the atmosphere both in vivo and in vitro, the intestine was motionless in most cases. On the other hand, the abdominal-window-technique proved to be very useful to observe the gastrointestinal movements. (2) The operation was carried out under the aseptic precaution as follows: First the back of the animal was removed at its left side to make a retangular window of 8 X 1.5-4 cm, then ovaries and fallopian tubes on the left side were removed and lastly the window thus formed was covered with a 0.2 mm thick, transparent vinyl-plate, being sutured at its border to the back. In addition, the border of the window plate was firmly sticked to the back by means of adhesives, Aron Alpha A and Araldite. (3) a. In the region of the stomach situated just anal to the cardia contractions (stomach peristalses) recurrently started with a time interval of 21 to 32 sec, sweeping down the wall of the stomach with a velocity of 0.5 to 0.9 mm/sec, until they came to an end at the pylorus. b. In the small intestine, there recurrently occurred contraction waves with a time interval of about 45 seconds, traveling analwards with a velocity of about 0.3 mm/sec. c. In the large intestine, there were observed two kinds of movements, i.e., antiperistalses as well as mass peristalses. In the former contraction waves recurrently started at the anal end (coprodaeum) of the large intestine with a time interval of 18 to 25 sec, propagating oralwards with a velocity of about 1 min/sec, until they waned rapidly to disappear after propagating only a short distance (about 2 to 3 cm). In the latter powerful contractions occasionally started at the uppermost part of the large intestine to propagate analwards at first slowly with a velocity of about 0.15 mm/sec, and then rapidly with a velocity of about 0.5 mm/sec, until they arrived at the proctodaeum to expel a fecal mass 7 to 8 mm thick and 15 mm long.

Abdomen↗
PubMed1973

Neuronal organization of the central respiratory mechanisms in the brain stem of the cat.

In order to obtain basic evidence on the neuronal organization and localization of the central respiratory mechanism in the brain stem of the cat, the following experiments were undertaken: reexamination of the physiological meaning of apneusis and the gasp; differences in stability of spontaneous burst activity of respiratory neurons in the brain stem reticular formation; changes of spontaneous firing pattern of bulbar respiratory neurons in the isolated brain stem of the cat; changes of firing pattern of a pontine and a bulbar respiratory neuron during continuous recording of both unitary activities after brain stem transection at the pontomedullary junction; responses of respiratory neurons to electrical stimulation of the spinal cord; responses of respiratory neurons to electrical stimulation of the central cut end of the vagus nerve; effects of pentobarbitone on unitary activity of pontine and bulbar respiratory neurons. Based on the experimental result a preliminary scheme of a neuronal network of the central respiratory mechanism consisting of four subsystems of respiratory neurons: a primary neuron system; a satellite neuron system; an input neuron system; an output neuron system.

Animals↗