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Biomedical subjects

M Nakaya

Publications and source records attributed to M Nakaya.

At least 109 records · Page 6Linked to original sources
PubMed1985

[Effect of cisapride on contractile activity of the gastrointestinal tract].

Cisapride strongly stimulates gastrointestinal motor activity simultaneously from stomach to jejunum in the interdigestive state. The contractile pattern in the stomach was quite similar to that of the natural interdigestive mingrating contractions (IMC) in all respects, frequency, contractile force, and coordination between the gastric body and antrum. However, the cisapride-induced IMC-like contractions in the stomach did not migrate along the small intestine, nor were accompanied by an increase of plasma motilin concentration. Furthermore, both motilin and cisapride, given during the period of phase III, did not affect the phase III activity, but carbachol abruptly stopped phase III activity if it was given during phase III activity. On the contrary, cisapride-induced contractions in the stomach are completely inhibited by atropine, pentagastrin, CCK-octapeptide, but not by secretin. These findings provide additional evidence to indicate that the cisapride-induced contractions in the stomach are identical with the natural IMC in the respect of reactons to hormonal substances. No noticeable side effects were observed. In conclusion, cisapride is a unique compound to initiate IMC-like contractions in the stomach, but the contractions were not accompanied by an increase in plasma motilin concentration and did not migrate the small intestine.

Animals↗
PubMed1985

[Effect of proglumide on gastrointestinal motility and gastric secretion in the conscious state].

Proglumide suppressed neither phase III activity nor propagation of interdigestive migrating contractions (IMC) in the gastrointestinal tract. Furthermore, proglumide did not inhibit the gastric motor activity stimulated by pentagastrin, however, it suppressed the pH in Pavlov pouch stimulated by pentagastrin in the interdigestive state. On the contrary, in the digestive state, proglumide did not suppress the pH. That might be due to not only various gut hormones including gastrin, but also neural stimulation, mechanical stimulation and so on. In conclusion, antigastrin effect of proglumide is rather remarkable on the acid secretion not on the gastrointestinal motor activity. Proglumide may be an antacid without suppression of motor activity.

Animals↗
PubMed1984

Gastrointestinal motor-stimulating activity of macrolide antibiotics and analysis of their side effects on the canine gut.

For clarification of the nature of the side effects of macrolide antibiotics on the gastrointestinal tract, the motor-stimulating activity of these agents was studied in unanesthetized dogs. The results showed that erythromycin and oleandomycin, the 14-membered macrolides with two side chain sugars combined at C3 and C5 in a glycosidic linkage in parallel, strongly stimulate gastrointestinal motor activity, an action accompanied by vomiting at large doses. On the other hand, leucomycin, acetylspiramycin, and tylosin, belonging to a 16-membered macrolide with two side chain sugars in series combined at C5 of the lactone ring, did not induce contractions of the gastrointestinal tract. Motor-stimulating activity by erythromycin and oleandomycin was greatly inhibited by atropine sulfate. These results point to structure-physiological activity relationships.

Aminoglycosides↗
PubMed1984

Erythromycin mimics exogenous motilin in gastrointestinal contractile activity in the dog.

The gastrointestinal motor stimulating activity of erythromycin (EM) was studied in conscious dogs. It was found that a 20-min intravenous infusion of EM lactobionate at a dose of 50-100 micrograms (potency) X kg-1 X h-1 induced a group of strong contractions in the stomach and the duodenum, and the contractions migrated along the small intestine to the terminal ileum. The EM-induced contractions were quite similar to the naturally occurring interdigestive migrating contractions (IMC) in the gastrointestinal tract in frequency, contractile force, and duration of the contractions, migrating velocity, and accompanying peaks of plasma motilin concentration. The EM-induced contractions in the stomach were inhibited by feeding and intravenous infusion of pentagastrin (1.5 micrograms X kg-1 X h-1) but were not affected by secretin; these findings are identical to those found with the naturally occurring and motilin-induced contractions. Like motilin, EM stimulated motor activity only during the interdigestive state. We conclude that EM induces IMC associated with the release of endogenous motilin in the dog.

Animals↗
PubMed1983

Regulation of interdigestive contractions in the denervated stomach.

The effects of thiopental sodium on the regulation of interdigestive migrating contractions (IMC) in the stomach were investigated in dogs with extrinsically denervated fundic pouches. During the interdigestive state, strong phasic contractions in the pouch took place consistently in accordance with the IMC in the main stomach. The cyclic increase in plasma motilin concentration was more closely correlated with the increase in contractile activity in the pouch than the increase in the main stomach. General anesthesia by thiopental sodium promptly inhibited the IMC in the main stomach but the contractile activity in the pouch was not affected but gradually decreased in proportion to the decrease in plasma motilin concentration. In conclusion, contractile activity in the extrinsically denervated pouch, which is quite independent of the CNS, is directly controlled by a humoral factor(s), motilin. However, interdigestive motor activity in the extrinsically intact stomach appears to be regulated by the CNS as well as peripheral circulation humoral factors.

Anesthesia, General↗
PubMed1983

Inhibition of interdigestive contractile activity in the stomach by peptide YY in Heidenhain pouch dogs.

The inhibitory effect of peptide YY on contractile activity in the innervated main stomach and the vagally denervated fundic pouch in conscious Heidenhain pouch dogs was investigated. Peptide YY was given in i.v. bolus injections of doses between 12.5 and 100 pmol/kg body wt. During the digestive state, 2-3 h after feeding, peptide YY was found to have no effect on contractile activity in either the innervated or the vagally denervated stomach. In the interdigestive state, it was found that peptide YY inhibited the interdigestive migrating contractions in the innervated main stomach dose-dependently for 1.2 +/- 0.1 to 5.8 +/- 0.3 min, but did not affect pouch contractions at all. This peptide, however, did not influence the cycle of the interdigestive migrating contractions. Pentagastrin, on the other hand, suppressed the interdigestive migrating contractions in the innervated main stomach when the bolus doses were greater than 300 pmol/kg body wt, but did not inhibit pouch contractions completely with this dose. Atropine (0.05 mg/kg body wt) suppressed contractions in both the main stomach and the vagally denervated pouch. Peptide YY inhibits the interdigestive migrating contractions in the stomach through the extrinsic nerves.

Animals↗
PubMed1981

Neurohormonal control of gastrointestinal motor activity in conscious dogs.

Interdigestive migrating contractions (IMC) were analyzed for their occurrence interval, duration, migrating velocity, and frequently in long term records obtained by means of chronically implanted force transducers in the main stomach and the extrinsically denervated fundic pouches or in the intact jejunum and the extrinsically denervated Thirty loop in 10 conscious dogs. Plasma immunoreactive motilin (IRM) was measured simultaneously. It was found that concomitant occurrence of IMC in the main stomach and pouch was closely associated with increase in plasma IRM concentration. On the other hand, in the extrinsically denervated jejunal loop, IMC-like contractions occurred independently of and more frequently than those in the intact jejunum and did not correlate with an increase in IRM concentration. It is concluded that gastric motor activity is under humoral control but in the jejunum, autoregulation by the intrinsic nerve plexus is more predominant than humoral factor(s).

Animals↗
PubMed1981

Variation in canine exocrine pancreatic secretory activity during the interdigestive state.

Interdigestive changes in pancreatic volume flow, gastric motor activity, and intraduodenal pH were monitored automatically in eight dogs. As a result, two different periods of pancreatic secretion were found to occur alternately during the interdigestive state: one a secretory period (2.2 +/- 0.32 ml/10 min with high protein and low bicarbonate concentration) and the other a nonsecretory period. The secretory period corresponded to the interdigestive phase II and III contraction period in the stomach, and the nonsecretory period coincided with the motor quiescent period in the stomach. However, another secretory period was identified during the interdigestive state; it occurred when the intraduodenal pH went below 7.0, and no typical interdigestive contractions were observed in the stomach. The secretory rate was 3.7 +/- 0.33 ml/10 min and was low in protein and high in bicarbonate concentration. The present study demonstrates that basal pancreatic secretory activity is never uniform but fluctuates with motor events in the stomach. However, its control mechanism remains unknown at present.

Animals↗
PubMed1979

Changes in enzymes and potassium content of the neuromuscular systems of albino rats during prolonged exposure to simulated hypogravics.

With respect to neuromuscular function, aldosterone activity, enzymatic and potassium (K) metabolism of organ tissues were investigated during the stress and adaptation stabilized phases of hypodynamically stressed rats. During adaptation, muscle tissue enzymes, such as aldolase, showed no change until the 35th day. The decrease of succinic dehydrogenase (SDH) was evident at 7 days. Lactic dehydrogenase (LDH) and creatine phosphokinase (CPK) serum levels increased transiently on the 18th day; this implied the development of muscular atrophy. A decrease in the 42K uptake of muscle was found from the 18th day onward. In the brain, a progressive decrease of aldolase was observed. 42K uptake showed no change in the brain, but the K content increased at both 7 and 18 days of exposure. The increase of cholinesterase (ChE) was more remarkable in the brain than in muscle, although transient. We suggest that the brain plays an important part in the adaptation process, through increasing or maintaining the functions of the neuromuscular excitation system during the 7-18 days of hypodynamic exposure.

Adaptation, Physiological↗
PubMed1977

Dynamics of sleep patterns during prolonged simulated weightlessness.

Subjects immersed for 6 days in water, simulating weightlessness, exhibited marked changes in the total time spent in sleep and in the percentage of that time spent in each sleep stage. The length of time spent in Stage 4 deep sleep and in REM sleep decreased in the first half of the 6-day immersion period. During the latter half of the immersion period, a clear adaptive response was observed in the sleep patterns: the sequential appearance of the different stages of sleep and the percentage of time spent in the six stages of sleep showed a clear approach to the pre-immersion data. During the 3-day post-immersion period, the patterns approached the normal pre-immersion levels, although there was some overshoot or a negative phase period characterizing this approach. By the sixth day of immersion, the percentage of time spent in each stage of sleep had returned to near normal pre-immersion values, but the total time spent in sleep was still somewhat less than normal. This fact suggests that, once adapted to a condition of weightlessness, the sleep requirement may be less than during normal ambulatory life. During the post-immersion period, the pattern of Stage 4 sleep at early evening, midnight and dawn showed no special reactive characteristics, but rather a clear recovery towards the original pattern. On the other hand, at the duration of REM sleep, it overshot the pre-immersion values at the beginning of the post-immersion period, and then returned to the original pattern. These experiments suggest that some of the changes in sleep patterns which are observed under conditions simulating weightlessness may be adaptive.

Adaptation, Physiological↗
PubMed1976

Metabolic and hormonal mechanisms of mineral metabolic adaptation to induced hypokinetics in rats.

During simulated hypokinetics, many biological functions have a tendency to stabilize at different levels with the passing of time. In this experiment, hypokinetic exposure was induced in albino rats by the suspension method for 5 weeks. A new plateau in urinary K+ excretion was attained during the third week, after a transient decrease during the first week. Since the formation of this steady plateau is considered a manifestation of the adaptation of this function, the hypokinetic exposure period was divided into a prestabilized phase and a stabilized phase. To ascertain the biochemical mechanisms of this adaptation process, the effects of aldosterone and anti-aldosterone substances (e.g., tetracycline) on K+ and Na+ excretion patterns in each phase were investigated. Decreasing aldosterone activity in the prestabilized phase and increasing activity in the stabilized phase are recognized as one of the main factors in the renal adaptation process to hypokinetics.

Adaptation, Physiological↗