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Biomedical subjects

I Takayanagi

Publications and source records attributed to I Takayanagi.

At least 235 records · Page 13Linked to original sources
PubMed1982

Effects of some ergot alkaloids on dopamine receptors of molluscan smooth muscle.

Some ergot alkaloids relaxed catch contraction of an isolated molluscan smooth muscle (anterior byssus retractor muscle of Mytilus edulis). Haloperidol, a competitive dopamine antagonist, shifted the dose response curves of ergot alkaloids, but methysergide did not. Bromocriptine, a potent dopaminergic ergot alkaloid, did not relax catch contraction. These results suggest that relaxation of catch contraction by some ergot alkaloids is mediated through dopamine receptors of this muscle, but dopamine receptors of this muscle seem to be somewhat different from those of mammalian brain.

Animals↗
PubMed1982

Effects of morphine, codeine and codeine-epoxide on calcium uptake into the synaptosomes isolated from naive and tolerant rats.

We studied the effects of morphine, codeine and codeine-7,8-oxide (codeine-epoxide) on the stimuli-induced 45Ca2+ uptake into the synaptosomes isolated from naive and tolerant rats and clarified the relationship between pharmacological responses of opiates and synaptosomal 45Ca2+ uptake. In vitro additions of morphine and codeine-epoxide inhibited the synaptosomal 45Ca2+ uptakes induced by two stimuli, that is, high KCl and veratrine in a concentration-dependent manner; and the inhibitions could be reversed by naloxone. However, the inhibitory action of codeine was less than that of morphine and codeine-epoxide. Since the potency ratios of the anti-nociceptive action of opiates are higher in the order of morphine greater than codeine-epoxide greater than codeine, the inhibitory effect of opiates on synaptosomal 45Ca2+ uptake may partly relate to their antinociceptive action. On the other hand, opiates significantly increased synaptosomal 45Ca2+ uptake when animals were rendered tolerant to their antinociceptive action, and data showed that the elevation of stimuli-induced 45Ca2+ uptake into the synaptosomes isolated from tolerant animals may reflect the degree of antinociceptive tolerance. Our results support the hypothesis that some of the pharmacological effects of opiates may be attributable to its ability to affect calcium accumulation in synaptosomes.

Analgesics↗
PubMed1982

Specific 3H-haloperidol binding to dopamine receptors in the anterior byssus retractor muscle of Mytilus edulis.

The anterior byssus retractor muscle (ABRM) of Mytilus edulis has specific dopamine receptors. We carried out a radioligand binding assay for dopamine receptors in ABRM using (3H)-haloperidol as the radioligand. High affinity binding of (3H)-haloperidol has been shown. Scatchard analysis showed a single component of binding with an apparent equilibrium constant (KD) of 1.6 nM and a maximal number of binding sites (Bmax) of 219 fmoles/mg protein. Some dopamine antagonists displaced 3 nM (3H)-haloperidol binding, and the IC50 and Ki-value of these drugs were calculated. Considering these results, this muscle is thought to be suitable for a study of the dopamine receptors.

Animals↗
PubMed1982

Effects of anti-asthmatic drugs on airway resistance and plasma level of cyclic AMP in guinea pig.

Effects of anti-asthmatic drugs on airway resistance and plasma level of cyclic AMP were investigated in guinea pigs sensitized and non-sensitized with egg-albumin. Histamine increased airway resistance in the both groups of guinea pigs, and guinea pigs sensitized with egg-albumin were more sensitive to histamine. Anti-asthmatic drugs inhibited dose-dependently the increase of airway resistance caused by histamine. Sensitization with egg-albumin decreased the potencies of the beta-adrenoceptor stimulants, salbutamol and isoprenaline, but not that of aminophylline. The plasma level of cyclic AMP was increased by salbutamol and isoprenaline, but not by aminophylline. The increased plasma level of cyclic AMP by beta-adrenoceptor stimulants was not attenuated by sensitization with egg-albumin.

Airway Resistance↗
PubMed1982

Effect of morphine on the stimuli-induced calcium uptake into synaptosomes isolated from morphine-tolerant rats.

Effects of morphine on calcium uptake into synaptosomes isolated from acutely or chronically morphine-tolerant rat brain was studied. Addition of morphine inhibited the depolarization-stimulated uptake of calcium without affecting uptake under nondepolarizing conditions. This inhibition was prevented by simultaneous addition of naloxone with morphine before calcium uptake was initiated. Acute tolerance to morphine increased depolarization-stimulated synaptosomal calcium uptake. On the other hand, chronic exposure of rats to morphine to elicit tolerance to and physical dependence on morphine did not influence synaptosomal calcium uptake. However, these preparations apparently lost the ability of in vitro morphine-inhibition of calcium uptake into the synaptosomes. Our results suggested that adaptive changes of synaptosomal calcium uptake produced by exposure to morphine may be involved in tolerance and physical dependence development, but influence of morphine on calcium uptake by the synaptosomes isolated from the rats acutely tolerance to morphine was differed from that of chronic tolerant rats.

Absorption↗
PubMed1982

A possible mechanism of a new antispasmodic drug, 2-(1,2-benzisoxazol-3-yl)-3-[2-(2-piperidinoethoxy) phenyl]acrylonitrile (SX-284).

A newly synthesized drug, SX-284, depressed the twitch response of the ileum from guinea pig to electrical stimulation at 0.1 Hz. SX-284 proved to be almost as active as atropine on electrically stimulated ileum. The responses of guinea pig ileum to nicotine and serotonin were also inhibited by SX-284. However, SX-284 did not influence the release of transmitters from the motor, sympathetic, nonadrenergic inhibitory, noncholinergic excitatory nerves, and responses of various smooth muscles mediated through drug receptors, and at these doses, SX-284 inhibited the release of acetylcholine from the vagus nerve. These facts indicate that SX-284 specifically inhibits the acetylcholine release from the vagus nerve. Furthermore, spontaneous movement of the guinea pig ileum was dose-dependently depressed by SX-284. The potency ratio for SX-284 relative to atropine was 1.7.

Animals↗
PubMed1981

A dual action of papaverine on calcium uptake by microsomal fraction isolated from rat uterus.

The effects of papaverine, cyclic AMP and MIX(3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor) on calcium uptake by a microsomal fraction from rat uterus were tested in the presence of 3 mM ATP. Papaverine potentiated calcium uptake in the presence of oxalate but inhibited it in the absence of oxalate. However, cyclic AMP and MIX did not influence calcium uptake, neither in the presence nor the absence of oxalate. These results suggest that calcium uptake by plasma membrane-derived vesicles in the absence of oxalate is inhibited by papaverine and that papaverine potentiated calcium uptake by the internal membranes in the presence of oxalate. They suggest also that the stimulatory action of papaverine involves a cyclic AMP-independent mechanism in addition to the mechanism via cyclic AMP.

Animals↗
PubMed1981

Effects of smooth muscle relaxant (aspaminol) on Ca-uptake by mitochondrial and microsomal fractions from rat uterus.

A smooth muscle relaxant, Aspaminol (1,1-diphenyl-3-piperidinobutanol hydrochloride) relaxed a KCl-depolarized rat uterus and shifted a dose response curve of CaCl2 towards higher doses. Asparminol, a teritary amine, may penetrate into the KCl-depolarized muscle cells. In order to study mechanisms for relaxation of the KCl-depolarized rat uterus by Aspaminol, effects of Aspaminol on Ca-uptake by mitochondrial and microsomal fractions from the rat uterus were studied. Aspaminol inhibited Ca-uptake by both fractions. Inhibition of Ca-uptake by the mitochondrial fraction seems to increase intracellular Ca2+. Therefore, inhibition of Ca-uptake by the mitochondrial fraction is considered to be not associated with relaxation of uterus induced by Aspaminol. Since the microsomal fraction is known to form microsacs, the microsomal fraction was used as smooth muscle models. Inhibitory effect of Aspaminol on Ca-uptake by the microsomal fraction suggest a decrease in the intracellular concentration of Ca2+ of the uterine smooth muscle relaxed under the influence of Aspaminol.

Animals↗
PubMed1981

Effects of phenobarbital on plasma concentration of phenytoin and mortality of mice treated with phenytoin after electroshock.

THe effects of phenobarbital on the plasma concentration of phenytoin and mortality of the phenytoin-treated mice were mainly studied. The plasma concentration of phenytoin estimated in the live mice after electroshock was significantly higher than that in the dead mice, suggesting that biological activity of phenytoin is dependent on its plasma concentration where individual difference seems to be large. Though the pretreatment of mice with phenobarbital lowered the plasma concentration of phenytoin, all the mice were alive after electroshock with further treatment with phenobarbital and phenytoin. These results suggest that combination of phenobarbital with phenytoin for the treatment of epileptic patients may be feasible.

Animals↗
PubMed1981

Physiological calcium ion concentration and a cholinergic drug on activity of particulate guanylate cyclase in guinea pig taenia caecum.

The microsomal fraction derived from the taenia caecum of guinea pigs was used as particulate guanylate cyclase preparation. The guanylate cyclase activity was not influenced by butyltrimethylammonium bromide and Ca2+ (4.0 to 24 X 10-7 M). The results suggest that the particulate guanylate cyclase is not activated by the drug-receptor interaction and also by the increase of intracellular Ca2+ concentration. Therefore, the increase of tissue level of cyclic GMP brought about in the guinea pig taenia caecum might be due to activation of soluble guanylate cyclase following the increase in the intracellular Ca2+ concentration.

Animals↗
PubMed1981

Inhibition of Ca-movement and mechanical movement in rabbit taenia coli by a smooth muscle relaxant (suloctidil).

A smooth muscle relaxant (suloctidil) relaxed a contractile response of taenia coli to acetylcholine and noncompetitively depressed a dose response curve of Cacl2 Ca-uptake by the microsomal fraction was inhibited by suloctidil. Its noncompetitive antiacetylcholine activity and inhibitory action on Ca-uptake were not influenced by an increase of external Ca-concentration. Ca-release from the Ca-incorporated microsomal fraction was not significantly influenced by suloctidil. These results suggest that suloctidil inhibit Ca-influx noncompetitively, thus inducing smooth muscle relaxation.

Animals↗
PubMed1981

Effects of cocaine on Ca-mobility in microsomal fraction from rat vas deferens.

Cocaine (3 x 10(-5) M) has been reported to potentiate maximal contraction induced by several stimulants, and this phenomenon might be ascribed to the postsynaptic action. The present study was undertaken to observe the influences of cocaine on Ca-movements, that is, Ca-uptake and Ca-release, in the microsomal fraction of the prostatic half of the rat vas deferens. In this study, it was shown that cocaine potentiated Ca-uptake at the lower concentration (10(-6) M) of Ca2+, but had no influence upon Ca-release and also that cocaine significantly increased the rate of Ca-uptake. These results suggest that cocaine promotes binding of Ca ions with the surface sites of smooth muscle membrane concerned with Ca-influx process and thereby potentiates maximal contractions elicited by different stimulants.

Animals↗
PubMed1981

Dopamine receptor in anterior byssus retractor muscle of Mytilus edulis.

Effects of dopamine, N-methyl-, ethyl- and propyl-derivatives of dopamine, and alpha- and beta-adrenoceptor stimulants on catch contraction of anterior byssus retractor muscle of Mytilus edulis were tested. The test drugs except the beta-adrenoceptor stimulants relaxed catch contraction. Dopamine was most active and substitution of amino group in dopamine with ethyl and propyl decreased activity considerably. The concentration-curves of dopamine, its derivatives and norepinephrine shifted in parallel with application of haloperidol but were not influenced by the alpha- and beta-adrenoceptor antagonists. These results suggest that relaxation of catch contraction by catecholamines is mediated through a dopamine receptor. This muscle is considered to be suitable for a study of the dopamine receptor.

Animals↗
PubMed1981

Possible mechanisms of stimulatory action of papaverine on calcium-uptake by rat uterine microsomal fraction.

Effects of papaverine and cyclic AMP on Ca-uptake by the microsomal fraction from rat uterus were studied. Papaverine (3 x 10(-5) M) potentiated Ca-uptake by the microsomal fraction in the presence of potassium oxalate. However, cyclic AMP and MIX (3-isobutyl-1-methylxanthine; 1 mM), a potent phosphodiesterase inhibitor, did not influence Ca-uptake by the microsomal fraction in the presence of potassium oxalate. Cyclic AMP in concentrations of 10(-8) to 10(-4) M did not influence Ca-uptake by the microsomal fraction in the presence of potassium oxalate. In the absence of potassium oxalate, papaverine and Aspaminol (1,1,-diphenyl-3-piperidinobutanol hydrochloride), a nonspecific smooth muscle relaxant, inhibited Ca-uptake by the microsomal fraction and cyclic AMP had no influence on this uptake. These results suggest that papaverine potentiated Ca-uptake by membranes such as sarcoplasmic reticulum, in the presence of potassium oxalate and inhibited Ca-uptake by the plasma membrane-derived vesicles in the absence of potassium oxalate. These results suggest that relaxation of smooth muscle by papaverine is related to a cyclic AMP-independent mechanism as well as to a mechanism mediated via cyclic AMP.

Animals↗
PubMed1981

Effect of 1,1-diphenyl-3-piperidinobutanol hydrochloride (Aspaminol) on the stimuli-induced calcium uptake in rat brain synaptosomes.

Effects of 1,1-diphenyl-3-piperidinobutanol hydrochloride (Aspaminol), a nonspecific smooth muscle relaxant, on the uptake of calcium in the synaptosomes of rat brain were studied, using two stimuli i.e. high KCl and ATP. We also studied the effect of Aspaminol on the analgesic response of rat hindpaw using the Randall-Sellito test. The addition of Aspaminol inhibited the stimuli-induced calcium uptake in a concentration dependent manner. Aspaminol inhibited the high KCl induced calcium uptake competitively against the external calcium concentration. These findings suggest that Aspaminol may act on the surface of the synaptosomal membranes. In case of ATP stimulated calcium uptake, Aspaminol reduced the rate of uptake and maximal level of the synaptosomal calcium, and did not appear to have any effect on the rate of calcium release. These findings suggest that the inhibitory effect of Aspaminol can be mainly attributed to inhibition of the calcium influx, but not to acceleration of calcium efflux. In the five weeks old rats, Aspaminol did not influence the responses in the paw pinch test, but, in the weanling rats (about three weeks old). Aspaminol had a slight effect on the responses in the paw pinch test. This discrepancy may be due to difficulties in passing through the blood-brain barrier. Our findings suggest that a certain relationship may exist between the analgesic effect and the calcium uptake in the synaptosomes.

Adenosine Triphosphate↗