• Korean Journal of Veterinary Research
• /
• v.15 no.2
• /
• pp.199-201
• /
• 1975

In order to investigate the effect of aconitine upon the parasympathetic innervation, the isolated rabbit duodenal preparation pretreated with atropine and tetrodotoxin were observed. The results obtained in this work were summerized as follows: 1. The excitatory response was evoked by the administration of aconitine ($100{\mu}g/ml$). 2. The contraction was blocked by the pretreatment with atropine ($10{\mu}g/ml$). 3. The contraction was completely blocked by the pretreatment with tetrodotoxin($10{\mu}g/ml$). These experimental evidences indicate that the excitatory response by aconitine is due to the parasympathetic nerves.

• Korean Journal of Veterinary Research
• /
• v.14 no.2
• /
• pp.207-210
• /
• 1974

Pharmacological investigation was performed in chickens which were pretreated with reserpine. Transmural stimulations were given to the isolated jejunum of chickens and studied the responses and the effects of dibenamine, propranolol, atropine and tetrodotoxin on them. The results obtained were summerized as follows: 1. Three different patterns of response were obtained from the isolated jejunum of non-treated chickens after giving them transmural stimulation. The first pattern was contraction followed by relaxation, the second pattern was contraction only and the third pattern was relaxation only. 2. The transmural stimulation of the jejunum preparations evoked relaxation while the periarterial stimulation evoked contraction in the reserpinized chick. 3. The relaxation response to the transmural stimulation was not affected by the pretreatment with dibenamine, propranolol and atropine. 4. The relaxation response to the transmural stimulation was abolished by tetrodotoxin. The results obtained in these studies indicate that the relaxation response to the transmural stimulation is due to non-adrenergic inhibitory fibers.

• The Korean Journal of Physiology
• /
• v.29 no.1
• /
• pp.103-111
• /
• 1995

Intracellular recordings were obtained from Purkinje cells in rat cerebellar slices maintained in vitro. Adding tetrodotoxin to the superfusion solution produced a typical pattern of repetitive burst firing consisting of a cluster of action potentials followed by a long hyperpolarization. TTX-induced oscillatory activity was not due to modulation of membrane potential although underlying mechanisms for maintenance of oscillatory activity were influenced by membrane voltage. The mechanism of TTX-induced oscillation was not related to the presence or amplitude of $I_h$ and could still induce the oscillatory activity after blockade of $I_h$ by cesium. The result from an experiment in which QX-314 was injected intracellularly strongly suggested that TTX-induced oscillatory firing activity was due to blockade of post-synaptic $Na^{+}$ currents intrinsic to PCs.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.3
• /
• pp.263-265
• /
• 1990

• The Korean Journal of Physiology and Pharmacology
• /
• v.22 no.6
• /
• pp.649-660
• /
• 2018

Migraine is a neurological disorder characterized by recurrent and disabling severe headaches. Although several anticonvulsant drugs that block voltagedependent $Na^+$ channels are widely used for migraine, far less is known about the therapeutic actions of carbamazepine on migraine. In the present study, therefore, we characterized the effects of carbamazepine on tetrodotoxin-resistant (TTX-R) $Na^+$ channels in acutely isolated rat dural afferent neurons, which were identified by the fluorescent dye DiI. The TTX-R $Na^+$ currents were measured in medium-sized DiIpositive neurons using the whole-cell patch clamp technique in the voltage-clamp mode. While carbamazepine had little effect on the peak amplitude of transient $Na^+$ currents, it strongly inhibited steady-state currents of transient as well as persistent $Na^+$ currents in a concentration-dependent manner. Carbamazepine had only minor effects on the voltage-activation relationship, the voltage-inactivation relationship, and the use-dependent inhibition of TTX-R $Na^+$ channels. However, carbamazepine changed the inactivation kinetics of TTX-R $Na^+$ channels, significantly accelerating the development of inactivation and delaying the recovery from inactivation. In the current-clamp mode, carbamazepine decreased the number of action potentials without changing the action potential threshold. Given that the sensitization of dural afferent neurons by inflammatory mediators triggers acute migraine headaches and that inflammatory mediators potentiate TTX-R $Na^+$ currents, the present results suggest that carbamazepine may be useful for the treatment of migraine headaches.

• The Korean Journal of Physiology
• /
• v.10 no.1
• /
• pp.41-48
• /
• 1976

Tetrodotoxin (TTX) is the purified active principle responsible for tetrodon (Puffer-fish) poisoning which has long been known in the Orient. The pharmacological actions of TTX have been rather extensively investigated. Two of the most prominent effects of intravenousely administered TTX are severe hypotension and respiratory paralysis resulting from its depressant actions on tissues. This depressant actions of TTX in turn result from the selective inhibition of sodium-carrying mechanism which is essential to generation of the action potential. TTX differs from local anesthetics in that it does not affect potassium conductance. Although the mechanism of the hypotensive action of TTX remains a subject of controversy, most investigator agree that TTX-induced hypotension is caused by alteration in the blood vessels rather than the heart. Not only the study on the effects of TTX on cardiac function is meager but the results of reported works are often contradictory. The present study was undertaken to investigate the effect of TTX on the electrocardiogram of the rabbit and to compare them with well known electrocardiographical characteristics found in digitalis and quinidine intoxicated animals. The results obtained from the present study are summarized as follows. 1. No changes were found in P-R interval and QRS duration after i.v. administration of $1.0\;{\mu}g/kg\;to\;1.5\;{\mu}g/kg$ TTX to the animals. It is obvious that there were no conduction disturbance between atria and ventricles as well as in the ventricular tissue. 2. In $1.0\;{\mu}g/kg$ TTX group, S-T interval and T-P segment were not changed whereas marked changes were observed in $1.5\;{\mu}g/kg$ TTX group. 3. The first and second degree A-V blocks appeared in the $2.0\;{\mu}g/kg$ TTX group. 4. TTX differs from digitalis and quinidine in that it does not cause S-T interval depression and T-wave inversion. In contrast with digitalis, TTX caused Q-T interval prolongation.

• Biomedical Science Letters
• /
• v.28 no.1
• /
• pp.42-49
• /
• 2022

Tetrodotoxin (TTX) is a natural neurotoxin found in several species of puffer fish belonging to Tetraodon fugu genus and has been reported to affect processes such as proliferation, metastasis and invasion of various cancer cells. However, it was not revealed which genes were influenced by these reactions. In this experiment, it was examined in human SW620 colorectal cancer cells. The proliferation of SW620 cells was significantly reduced when treated with 0, 1, 10 and 100 μM TTX for 48 h. It was confirmed using Annexin V-propidium iodide staining that some apoptosis was induced. Differentially expressed genes (DEGs) affecting cell proliferation through RNA sequencing (RNA-seq) were selected. The expression change of DEGs was confirmed by conducting quantitative real-time polymerase chain reaction (qRT-PCR). As a result, the mRNA expression of FOS and WDR48 genes was found to be increased in the 100 μM TTX treatment group compared to the control group. On the other hand, the mRNA expression of ALKBH7, NDUFA13, RIPPLY3 and SELENOM genes was found to be reduced, and in the case of the ALKBH7 gene was identified to show significant differences. This experiment suggests that TTX can be used as an important fundamental data to elucidate the mechanism that inhibits the proliferation of SW620 cells.

• The Korean Journal of Pharmacology
• /
• v.26 no.1
• /
• pp.55-66
• /
• 1990

In both resting and opsonized zymosan activated neutrophils, ATP stimulated superoxide generation, whereas adenosine inhibited it slightly. The superoxide generation in activated neutrophils to ATP was greater than that of resting neutrophils. In $Ca^{++}$ free medium, inhibitory effect of adenosine on superoxide generation was detectable, whereas ATP did not have any effect. The stimulatory effect of ATP on superoxide generation was inhibited by adenosine in a dose dependent manner. Neither ATP nor adenosine had any effect on NADPH oxidase acitivity. Effects of ATP or adenosine on superoxide generation were more prominent than that by other triphosphate nucleotides or nucleosides. ATP and ADP further stimulated $Ca^{++}$ uptake and increased cytosolic free $Ca^{++}$ level in neutrophils activated by opsonized zymosan, but adenosine inhibited a $Ca^{++}$ mobilization. Verapamil effectively and tetrodotoxin slightly inhibited an increase of cytosolic free $Ca^{++}$ level induced by ATP. Inhibitory effect of either verapamil or tetrodotoxin on superoxide generation in the ATP plus opsonized zymosan-activated neutrophils was greater than in the cells activated by opsonized zymosan alone. Tetraethylammonium chloride had no apparent effect on superoxide generation. CCCP, 2,4-dinitrophenol, diphenylhydantoin and procaine all inhibited superoxide generation in neutrophils activated by opsonized zymosan. Among these, CCCP only inhibited a stimulatory effect of ATP. ATP further stimulated a loss of sulfhydryl groups in activated neutrophils, whereas adenosine had no effect on it. These results suggest that functional responses of neutrophils may be regulated at least partly by purines. ATP and adenosine may further after functional responses of activated neutrophils through their effect on $Ca^{++}$ uptake, membrane phosphorylation and oxidation of soluble sulfhydryl groups.

• Journal of Yeungnam Medical Science
• /
• v.8 no.2
• /
• pp.138-149
• /
• 1991

This study was aimed at investigation of the stimulatory innervations on the rat urinary bladder. Detrusor muscle strips of 15 mm long were suspended in isolated muscle chambers containing 1 ml of PSS maintained at $37^{\circ}C$ and aerated with 95% $O_2/5%CO_2$. Isometric myography was perfomed, and the results were as followings : Muscle strips showed "on-contraction" by electric field stimulation (EFS) frequency-dependently. The EFS-induced contraction was not affected by hexamethonium, a ganglion blocker, but abolished, by tetrodotoxin, a nerve conduction blocker. Physostigmine, a cholinesterase inhibitor enhanced the EFS-induced contraction which was inhibited by hemicholinium, an inhibitor of choline uptake at the cholinergic nerve ending. Such an EFS-induced contraction was antagonized by atropine only partially, and the atropine-resistant portion was completely abolished by the desensitization of purinergic receptors by prolonged incubatin of the strips in the presence of high concentratin of ATP. Bethanechol, a cholinergic agonist, elicited concentration-dependent contraction. Adenosine triphosphate (ATP), a purinergic agonist, induced a weak but concentration-dependent contraction of short duration. Bethanechol-induced contraction was not affected by ATP-desensitization, and ATP-induced contraction was not affected by tetrodotoxin. These results suggest that there are at least two main stimulatory components of innervations in the detrusor muscle, cholinergic muscarinic and purinergic ; and those receptors are independent each other.

• Journal of Food Hygiene and Safety
• /
• v.27 no.1
• /
• pp.37-41
• /
• 2012

The current standard for testing tetrodotoxin (TTX) in foodstuffs is the mouse bioassay (MBA) in Korea as in many other countries. However, this test suffers from potential ethical concerns over the use of live animals. In addition, the mouse bioassay does not test for a specific toxin thus a sample resulting in mouse incapacitation would need further confirmatory testing to determine the exact source toxin (e.g., TTX, STX, brevotoxin, etc.). Furthermore, though the time of death is proportional to toxicity in this assay, the dynamic range for this proportional relationship is small thus many samples must be diluted and new mice be injected to yield a result that falls within the quantitative dynamic range. Therefore, in recent years, there have been many efforts in this field to develop alternative assays. High performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) has been emerged as one of the most promising options. A LC-MS-MS method involves solid-phase extraction (SPE) and followed by analysis using an electrospray in the positive ionization mode and multiple reactions monitoring (MRM). To adopt LC-MS-MS method as alternative standard for testing TTX, we performed a validation study for the quantification of TTX in puffer fish. This LC-MS-MS method showed good sensitivity as limits of detection (LOD) of $0.03{\sim}0.08{\mu}g/g$ and limits of quantification (LOQ) of $0.10{\sim}0.25{\mu}g/g$. The linearity ($r^2$) of tetrodotoxin were 0.9986~0.9997, the recovery were 80.9~103.0% and the relative standard deviations (RSD) were 4.3~13.0%. The correlation coefficient between the mouse bioassay and LC/MS/MS method was higher than 0.95.