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Biomedical subjects

S Nakajyo

Publications and source records attributed to S Nakajyo.

At least 37 records · Page 2Linked to original sources
PubMed1989

Inhibitory effect of lithium on muscle contractions caused by various stimulants in guinea-pig ileum.

The tonic contractions induced in the guinea-pig ileal longitudinal muscle by 60 mM KCl, carbachol, histamine or A23187 were inhibited similarly by Li+-substituted solution. There was a good correlation between the Li+-induced inhibition of contractions induced by these stimulants and the intracellularly accumulated Li+ content. In the experiment with fura-2, Li+-substituted solution inhibited the high-K+-induced contraction without decreasing the cytosolic Ca2+ level elevated by high-K+ solution. The concentration-response curve for Ca2+ in the skinned fiber was shifted to the right by pretreatment with Li+-substituted solution. These results suggest that the inhibitory mechanism of Li+ on the contractions by various stimulants partly involves the direct inhibition of the contractile proteins in the guinea-pig ileal longitudinal muscle.

Animals↗
PubMed1989

The effect of trifluoperazine on muscle tension and cytoplasmic Ca2+ level in guinea pig ileum.

In guinea pig ileal muscle strips, trifluoperazine (TFP) inhibited the high K+-induced contraction with an IC50 of 1.9 microM and the Ca2+-induced contraction in skinned fiber with an IC50 of 44 microM. TFP decreased the high K+-induced increase in cytoplasmic Ca2+ level at the concentration 3 microM, which did not inhibit the contraction in skinned fiber. It is suggested that the inhibitory effect of TFP on the high K+-induced contraction is mainly due to the decrease in cytoplasmic Ca2+.

Animals↗
PubMed1988

Palytoxin-induced K+ efflux from ileal longitudinal smooth muscle of the guinea-pig.

In guinea-pig ileal longitudinal smooth muscle, both palytoxin (PTX) and carbachol (CCh) increased K+ efflux with an EC50 of 1.8 X 10(-10) M and 4.1 X 10(-7) M, respectively. Atropine (10(-6) M) did not inhibit the K+ efflux due to PTX (3 X 10(-9) M), but completely inhibited the efflux due to CCh (10(-5) M). External Ca2+ removal and verapamil (10(-5) M) did not change the PTX-induced K+ efflux, although the CCh-induced K+ efflux was inhibited about 77% and 71%, respectively. PTX-induced K+ efflux was reduced to 31% by a depletion of intracellular Ca2+. Tetraethylammonium (15 mM) inhibited the K+ efflux due to PTX or CCh to 61% or 75%, respectively. The PTX-induced K+ efflux was also inhibited by cymarin (3 X 10(-8) M), ouabain (10(-5) M) and digitoxin (10(-5) M). These results suggest that the PTX-induced K+ efflux is less dependent on Ca2+ influx than that due to CCh. Furthermore, the binding sites for PTX in the ileal muscle of guinea-pig may be Na+, K+-ATPase, as has been suggested in other types of cells.

Acrylamides↗
PubMed1988

A comparative study on the contraction induced by high K+/Na+ deficient solution in rat uterus or urinary bladder.

In the present paper, effects of high K+/Na+ deficient solution on the rat uterus were examined on the mechanical response, wet weight of the tissue or rate of oxygen consumption, and they were compared with those in rat urinary bladder. In the uterus, isosmotic substitution of K+ for Na+ in a physiological salt solution (PSS) induced a contraction followed by a small sustained contraction, while hyperosmotic addition of KCl to PSS induced a sustained contraction. The hyperosmotic KCl addition increased the rate of oxygen consumption in comparison with that in PSS, and the substituted high K+/Na+ deficient solution decreased it as compared with that in the hyperosmotic KCl addition. Similar results were shown in the urinary bladder. At 120 min after application of the substituted high K+/Na+ deficient solution, the relative wet weight increased in the uterus, but did not change in the urinary bladder. Both the decrease in the developed tension and the increase in the wet weight of the uterus were prevented by the hyperosmotic addition of sucrose. In the urinary bladder, the decreased tension was significantly prevented by the hyperosmotic addition of NaCl to the PSS or substitution of pyruvate or oxalacetate for glucose, whereas it was slightly prevented by the hyperosmotic addition of sucrose. From these results, it is suggested that the decrease of the developed tension in isosmotically substituted high K+/Na+ deficient solution in rat uterus is probably due to cell swelling and that the inhibition of contraction in urinary bladder is mainly caused by the inhibition of glucose utilization by Na+ deficiency in the medium.

Animals↗
PubMed1988

Species differences in inhibitory effect of Li+ on high K+-induced contraction in the ileal longitudinal smooth muscle.

The effects of Li+ substitution for external Na+ in the medium on a 60 mN KCl (60K+)-induced contraction were compared in the ileal longitudinal smooth muscles isolated from monkey, rabbit, guinea pig and rat. Li+ substitution inhibited the 60K+-induced contraction in the ileum of all the animal species. Greater inhibitory effect was observed with the increase in external Li+ concentration and the increase in incubation period with Li+. Intracellular Li+ contents of these muscles also increased with the increase in external Li+ concentration and the incubation period. Thus, a good correlation was obtained between Li+-induced inhibition of 60K+-induced contraction and the increase in Li+ content. However, close examination revealed that the contraction in monkey and rat ileum was inhibited by much lower Li+ accumulation than that in guinea pig and rabbit ileum, suggesting the existence of species difference in the sensitivity of the ileal smooth muscle to the inhibitory effect of Li+ substitution, and a mechanism for the species differences in the inhibitory action of Li+-substitution was discussed.

Animals↗
PubMed1988

Effects of the high K+/Na+ deficient solution on mechanical response and wet weight of tissue in vas deferens and seminal vesicle in guinea-pig.

In the present experiments, we investigated contractions of guinea-pig vas deferens or seminal vesicle in various kinds of high K+ solution. The vas deferens showed a phasic contraction followed by a tonic one in hyperosmotic 65 mM KCl (hyper-65K+), isosmotic 60 mM or 120 mM KCl solution. However, isosmotic 154 mM KCl (iso-154K+) solution induced a large phasic contraction followed by a gradual relaxation. Applications of the high K+ solutions to the preparation of seminal vesicle showed almost similar results in tension to those of the vas deferens. In the vas deferens or seminal vesicle, an application of hyper-65K+ solution significantly decreased the relative value for the wet weight of the tissue at 120 min, but that of iso-154K+ solution did not affect the wet weight of both the muscles. In the vas deferens, an hyperosmotic addition of sucrose at a concentration of 25 to 100 mM slightly prevented the tension decreased by the iso-154K+ solution and slightly decreased the relative wet weight. In the seminal vesicle, increasing sucrose concentration significantly increased the tension, but decreased the relative wet weight. In both the muscles of vas deferens and seminal vesicle, an addition of pyrvate or oxalacetate (5.5 mM) to the iso-154K+ solution without glucose maintained the muscle tension at a maximal level in the iso-154K+ solution with glucose for 120 min. Further, the tension decrease in both the muscles induced by iso-154K+ solution was also prevented by hyperosmotic application of NaCl. From these results, it is suggested that the tension decrease by high K+, Na+-deficient solution in the vas deferens is mainly caused by an inhibition of glucose utilization by Na+-deficiency in the medium, however, the seminal vesicle is probably due to the cell swelling and partly the inhibition of glucose utilization by it.

Animals↗
PubMed1987

Inhibitory effect of beauvericin on a high K+-induced tonic contraction in guinea-pig taenia coli.

An inhibitory effect of beauvericin, a cyclodepsipeptide, on a high K+-induced contraction in guinea-pig taenia coli was compared with those of verapamil, an organic Ca2+ antagonist, and monensin, an inhibitor of mitochondrial respiration. Beauvericin (10(-5) M), verapamil (5 x 10(-7) M) or monensin (10(-6) M) markedly inhibited the tonic contraction, while these drugs showed less effect on the phasic contraction. Beauvericin at a lower concentration (10(-6) M) competitively inhibited the Ca2+-induced contraction in depolarized muscle, whereas higher concentrations (3 x 10(-6) or 10(-5) M) non-competitively inhibited this contraction. Verapamil (10(-8)-5 x 10(-7) M) competitively inhibited and monensin at a low concentration (10(-7) M) non-competitively inhibited this contraction. A contraction induced by 0.5 mM Ca2+ was inhibited by beauvericin with an IC50 (concentration needed for 50% inhibition) of 2.8 x 10(-7) M, verapamil with an IC50 of 2.9 x 10(-8) M, and nifedipine with an IC50 of 1.8 x 10(-9) M. 10(-6) M CGP 28392, a Ca2+ channel facilitator, increased the IC50 of beauvericin, verapamil or nifedipine. Although the inhibitory effect of monensin (10(-7)-10(-6) M) on the high K+-induced contraction was reduced under hypoxia, the effects of beauvericin (10(-7)-10(-5) M) and verapamil (10(-8)-10(-7) M) were not modified. Beauvericin (10(-5) M) changed neither the intracellular Na+ and K+ contents of the depolarized muscle nor the Ca2+-induced contraction in the chemically skinned taenia coli.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The properties of a high K+-induced contraction in the ileal longitudinal and circular muscles of cat.

Hypertonic 60 mM KCl (H 60K+) solution induced a phasic contraction followed by tonic one in the longitudinal (long.) and circular (circ.) muscles of cat ileum. Verapamil inhibited the tonic contraction in the long. or circ. muscle with IC50 of 2.0 X 10(-8) M or 1.0 X 10(-7) M, respectively. The sensitivity of the long. muscle to verapamil was higher than that of the circ. muscle. Ouabain (10(-5) M) increased or did not change the tonic contraction, and increased intracellular Na+ contents in the long. and circ. muscles in H 60K+ solution. Li+-substituted (1/5-1/2) solutions decreased the H 60K+-induced contraction in the long. muscle, but potentiated or did not change the contraction in the circ. one. The results with glucose removal, hypoxia, DNP application and a measurement of oxygen consumption showed that the H 60K+-induced contractions in the long. and circ. muscles are probably dependent on aerobic metabolism utilizing external glucose as well as endogenous substrates. In summary, properties of the H 60K+-induced contraction in the ileal long. of cat was not entirely similar to those of circ. muscles, but they were different from those of the ileal of other animal species and had some similarities to those of the guinea-pig portal vein.

Animals↗
PubMed1985

Species differences in the inhibitory effect of ouabain on high K-induced contraction in the ileal longitudinal muscle.

Effects of ouabain on a high K-induced contraction and intracellular Na and K contents of the ileal longitudinal muscle preparations isolated from various animal species was compared. In muscles of various animals (monkey, dog, cat, rabbit, guinea-pig, rat and mouse), the high K-induced contraction was inhibited by verapamil (5 X 10(-8) M) or ouabain (3 X 10(-6) M), and both the inhibitions were antagonized by an increase in external Ca in a competitive manner. Species differences were shown in the ouabain effect but not in the verapamil one. Regarding the sensitivity to ouabain, the muscles were divided into two groups, that is, the muscle from monkey, rabbit, guinea-pig or dog belongs to the high sensitivity group, and that from cat, rat or mouse belongs to the low one. The order of sensitivities of the muscles to ouabain in the relaxation was consistent with that in Na,K-ATPase inhibition, as reported by Repke et al. (1965). Intracellular Na contents of muscles were increased by an addition of ouabain to the high K solution, and the rate and amount of the accumulation of intracellular Na varied in these muscles. Except for the cat muscle, a high correlation was noted between the ouabain-induced relaxation and the amount of intracellular Na accumulation. However, the regression coefficients were variable: 4.1 in the monkey muscle, 2.2 in the rat one, and about 1.0 in the others. That is, the monkey muscle showing the high regression coefficient value probably has a high sensitivity to the inhibition of intracellular Na in the high K-induced contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

A comparative study on the contraction induced by high K/Na deficient solution in the trachea, gall bladder and urinary bladder in guinea-pig.

In the present paper, a comparative study of high K solution was carried out on the mechanical response, wet and dry weights of tissue, and extracellular space of 14C-sorbitol in the trachea, gall bladder, and urinary bladder of guinea-pig. Hyperosmotic addition of KCl to the physiological solution produced a sustained contraction, while isosmotic substitution of K for Na in the physiological solution induced a contraction followed by a small sustained one in the trachea, gall bladder or urinary bladder. At 120 min after application of the substituted KCl, Na deficient solution, it increased cell water content in the smooth muscle cells of the trachea or gall bladder, but did not change that in the urinary bladder. Both the inhibition of contraction and the swelling in the trachea or gall bladder were prevented by the hyperosmotic application of sucrose or NaCl. The substitution for NaCl with the K salts with more permeable anions (I- greater than NO3- greater than Cl-) produced a greater inhibition of contraction in the trachea and gall bladder. Although the impermeable anion C2H5CO2- did not inhibit the contraction in the trachea, this anion partially inhibited it in the gall bladder. On the other hand, the inhibition of contraction in the urinary bladder was prevented by addition of pyruvate, oxalacetate or NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Study on the contraction and oxygen consumption induced by high K, Na-deficient solution in the urinary bladder and gall bladder of guinea-pig.

In urinary bladder and gall bladder of guinea-pig, the application of hyperosmotic 65.4 mM K solution induced a tonic contraction and increased the rate of oxygen consumption two or three times. The increased O2 consumption maintained steady level during 120 min. In isosmotic 154 mM K, Na-deficient solution, the tonic contraction gradually decreased and oxygen consumption also showed a transient increase followed by a small one. In the urinary bladder, the addition of pyruvic acid completely prevented the decline of the tonic contraction by iso-154K solution at 120 min, but this addition partially prevented it in the gall bladder. Hyperosmotic application of sucrose partially prevented it in the urinary bladder, but completely recovered it in the gall bladder. When NaCl was applied to iso-154K solution, the decrease of tonic contraction was prevented by half in both the muscles. The application of pyruvic acid and NaCl prevented the reduction of oxygen consumption by iso-154K solution in the urinary bladder, but in the gall bladder, this had little effect. There was a close correlation (r = 0.950) between the muscle tension and the rate of oxygen consumption in the urinary bladder at 120 min under various conditions. In the gall bladder, a correlation (r = 0.875) was also found between both when the results by hyperosmotic addition of NaCl and sucrose were omitted. In the urinary bladder, tension cost, a ratio of O2 consumption rate (mumol O2/g/min) to developed tension (kg force/cm2), was large (0.206) and similar to that of taenia coli; and that of gall bladder was small (0.130) and almost similar to that of vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

On the inhibitory mechanism of bassianolide, a cyclodepsipeptide, in acetylcholine-induced contraction in guinea-pig taenia coli.

The effect of bassianolide (BASS), a cyclodepsipeptide, was investigated on mechanical response, membrane potential, intracellular Na and K contents and 45Ca uptake in response to acetylcholine (ACh) in guinea-pig taenia coli. BASS (10(-5) M) as well as verapamil (5 X 10(-7) M) and papaverine (3 X 10(-5) M) selectively inhibited the tonic component of the contraction induced by ACh (10(-5) M), but scarcely affected the phasic one. In contrast, atropine (3 X 10(-8) M) inhibited both components of contraction. BASS did not modify the change in membrane potential by ACh. BASS, ACh and the combination of both did not influence the intracellular Na and K contents and the 45Ca uptake. These data show that BASS seems unlikely to have the property of an ionophore. BASS slightly inhibited both the tonic and phasic components of contraction induced by 60 mM K in a non-selective manner, though verapamil and papaverine inhibited the tonic component more potently than the phasic one. Verapamil decreased the increased 45Ca uptake in the muscle soaked in 60 mM K medium, but BASS did not. Since BASS selectively inhibits the tonic component of the ACh-induced contraction, the inhibitory mechanism of BASS seems to be different from that of verapamil, papaverine or atropine; and the mechanism may be beyond the interactions with a binding activity of ACh to the muscarinic receptor, membrane potential and the contractile machinery of the intestinal smooth muscle.

Acetylcholine↗
PubMed1983

[Caerulein-induced contraction of the ileal longitudinal smooth muscle isolated from various animal species].

An effect of caerulein was studied on a contractile response of the ileal longitudinal smooth muscle isolated from seven animal species, monkey, dog, rabbit, guinea-pig, rat, vole and mouse. In isotonic recording, caerulein induced a contraction in the muscle isolated from all animal species. Sensitivities of ileal strips to caerulein in the contractile response was divided into three groups. That is, a high sensitive group; dog and guinea-pig, a middle sensitive group; rabbit and vole, a low sensitive group; monkey, rat and mouse. In another series of experiment, effect of several antagonists was examined on the caerulein-induced contraction in ileal muscle of dog, rabbit or guinea-pig. TTX inhibited the contractions in all the ilea. As the contraction was inhibited by atropine and scopolamine in dog ileum but not in rabbit one, the contraction may be due to an excitation of the cholinergic neuron or an excitation of non-cholinergic excitatory neuron, respectively. On the other hand, it is supposed that the contraction in guinea-pig ileum is involved to both the neurons because the contraction was inhibited partially by scopolamine and not by atropine. In conclusion, the ilea isolated from seven animal species showed species differences in sensitivity to caerulein in contractile response, and caerulein seems induces the contractions involving to different nervous systems in dog, rabbit or guinea-pig ileum, respectively.

Animals↗
PubMed1982

Inhibitory effect of bassianolide, a cyclodepsipeptide, on drug-induced contractions of isolated smooth muscle preparations.

Bassianolide (BASS) is a cyclodepsipeptide isolated from cultured mycelia of Beauveria bassiana and is pathogenic to insects. In a longitudinal muscle preparation from guinea pig ileum, 10(-6) M BASS almost irreversibly inhibited an isotonic contraction induced by acetylcholine (ACH) and made the dose-response curve shift in parallel to the right (pA2: 7.6). It also inhibited the contractions induced by carbachol, pilocarpine, histamine, 5-hydroxytriptamine (5-HT) and prostaglandin E2, but did not inhibit the contraction induced by barium or a high concentration (40-60 mM) of potassium (high K). When applied to the guinea pig vas deferens, 10(-8) - 10(-7) M BASS inhibited an isometric contraction induced by norepinephrine (NE) (3 x 10(-6) - 10(-5) M), phenylephrine (3 x 10(-6) - 10(-5) M) or ACH (10(-6) - 10(-5) M). When the contractions of the three agonists exceeded the concentrations mentioned above, BASS failed to exert an inhibitory effect upon any of these agonists. It also inhibited the contraction caused by carbachol and histamine, but did not inhibit that induced by barium or high K. BASS itself failed to cause the contraction or relaxation of both muscle preparations. From these results, it is suggested that BASS inhibits the contraction induced by an agonist which acts upon selective sites of smooth muscle cells, but which does not inhibit a contraction induced by an agonist that has an effect on non-selective sites of cells.

Acetylcholine↗
PubMed1982

[Drug sensitivity of the isolated stomach and ileal preparation from a vole].

It was compared a drug sensitivity of the stomach and ileum isolated from vole with those of guinea pig, rat or mouse. Histamine produced only a contraction in the vole stomach without a relaxation. Since the histamine-induced contraction was inhibited by tripelennamine, the contraction seems to be mediated by histamine H1-receptor. These results in the vole, being herbivorous, was different from those of bovine stomach that the drug induced a contraction through H1-receptor and a relaxation involved to the H2-receptor. The histamine-induced contraction in the guinea pig stomach or ileum was highly sensitive, but those of rat was less. On the contrary, a serotonin-induced contraction in the rat stomach or ileum was highly sensitive, however, those of guinea pig were less. Drug sensitivities of stomach and ileum from vole to histamine and serotonin were intermediate between those of guinea pig and rat.

Acetylcholine↗