• 대한수의학회지
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• 제33권2호
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• pp.199-209
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• 1993

The effects of ${\alpha}_1$-adrenergic stimulation on membrane potential, intracellular sodium activity $(a_N{^i{_a}})$, and contractility were investigated in the isolated papillary muscle of euthyroid, hyperthyroid, and hypothyroid guinea pigs. Cardiac alterations in the thyroid state have been shown to induce marked changes in action potential characteristics, the most pronounced shortening of action potential duration by hyperthyroidism and an increase in duration by hypothyroidism. $10^{-5}M$ Phenylephrine produced a decrease in $(a_N{^i{_a}})$ in euthyroid and hypothyroid preparations, but an increase in $(a_N{^i{_a}})$ in hyperthyroid ones. The major findings were that phenylephrine produced a stronger positive inotropic effect(PIE) without initial negative inotropic effect(NIE) in hyperthyroid preparations, while phenylephrine produced markedly NIE in hypothyroid ones. The alterations in membrane potential, $(a_N{^i{_a}})$, and contractility were abolished by $3{\times}10^{-5}M$ prazosin in hypothyroidism. In hypothyroid ventricular muscle, the decrease in $(a_N{^i{_a}})$ caused by phenylephrine were not abolished or reduced by $10^{-5}M$ strophanthidin, $10^{-5}M$ TTX, $3{\times}10^{-4}M$ lidocaine, or $100^{-5}M$ verapamil. These results indicate that the ${\alpha}_1$-adrenoceptor-mediated decrease in $(a_N{^i{_a}})$ is not associated with a stimulation of the $Na^+$-$K^+$ pump, inhibition of the $Na^+$ or $Ca^+$ channel in hypothyroid ventricular muscle. $10^{-5}M$ Phenylephrine decreased $(a_N{^i{_a}})$ but increased $(a_N{^i{_a}})$ in the presence of a PKC activator phorbol dibutyrate$(PDB_u)$. In conclusion, it is suggested that the following sequence of events in response to phenyleplhane occur in guinea pig ventricular muscle. First, changes in thyroid state may contribute to the ventacular electrophysiological propeties or ion transport system. Second, the adrenoceptor-mediated initial transient NIE may be associated with the decrease in $(a_N{^i{_a}})$ by PKC activation.

• Journal of Dental Anesthesia and Pain Medicine
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• 제17권1호
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• pp.29-35
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• 2017

Background: No study has compared lidocaine with articaine, each at a concentration of 4% and combined with epinephrine. The purpose of this study was to compare the effectiveness of 4% lidocaine with that of 4% articaine, with a concentration of 1:100,000 epinephrine added to each, in an inferior alveolar nerve block for surgery on impacted lower third molars. Method: This study was conducted at the Faculty of Dentistry, Mahidol University in Bangkok, Thailand. The randomized, single-blind, comparative split-mouth study was carried out in patients with symmetrically impacted lower third molars, as identified on panoramic radiographs. Each patient underwent surgery for the removal of the lower third molars by the same surgeon under local anesthesia at two separate visits, 3 weeks apart. The onset and duration of local anesthesia, intra-operative pain, surgical duration, and number of additional anesthetics administered were recorded. Results: The subjective and objective onset of action for the local anesthetics showed statistically significant differences (P < 0.05). However, the intra-operative pain, surgical duration, duration of local anesthesia, and number of additional anesthetics administered did not show statistically significant differences. Conclusion: The use of 4% articaine for the inferior alveolar nerve block was clinically more effective in the onset of subjective and objective anesthesia as compared with the use of 4% lidocaine. Based on the pain scores from the visual analogue scale, 4% lidocaine provided more analgesia during the procedure, and patients noted less intra-operative pain than with 4% articaine; however, the difference was not clinically significant.

• Journal of Dental Anesthesia and Pain Medicine
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• 제24권4호
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• pp.285-295
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• 2024

Background: In human dentition, the most commonly impacted teeth are the mandibular third molars (M3M). The removal or extraction of these teeth often causes anxiety in patients due to the perceived pain involved in the process. Therefore, pain must be effectively managed using anesthesia. The use of newer local anesthetic drugs can help minimize side effects and drug interactions. Traditionally, adrenaline is used as a vasoconstrictor along with lignocaine. When combined with lignocaine, the alpha agonists dexmedetomidine and clonidine can extend the duration of anesthesia, thereby reducing the need for additional pain-relieving medications. Methods: This study used a randomized, triple-blind, parallel-arm design. Sixty patients were screened, and 45 systemically healthy patients requiring unilateral surgical removal of impacted mandibular third molars with similar difficulty (moderate-to-difficult according to the Modified Pederson's Index) were included in the study. Patients were allocated into three groups as follows: Group A: 2% Lignocaine Hydrochloride with 1:100,000 Adrenaline, Group C: 2% Lignocaine Hydrochloride with 15 ㎍/mL Clonidine, and Group D: 2% Lignocaine Hydrochloride with 1 ㎍/mL Dexmedetomidine. The evaluated parameters were the time of onset of anesthesia, depth of anesthesia, hemodynamic parameters, and duration of postoperative analgesia. Results: Group D had a faster onset of action and prolonged duration of postoperative analgesia compared with Groups A and C. No statistically significant differences were observed between the three groups in terms of the depth of anesthesia and hemodynamic parameters. Conclusion: Group D exhibited a significantly more rapid onset of anesthesia than Groups A and C, and the postoperative analgesic effect in Group D was significantly prolonged (7.22 hours) compared with that in Groups A (4.54 hours) and C (2.1 hours). Patients receiving the Group D solution experienced an extended period of comfort without the need for analgesics for up to 7.22 hours post-procedure.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.38-38
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• 2003

The electrical properties of neurons are produced by the coordinated activity of ion channels (Hille, 1992). $K^{+}$ channels play a key role in shaping action potentials and in determining neural firing patterns. Small conductance $Ca^{2+}$-activated $K^{+}$ (S $K_{Ca}$ ) channels are involved in modulating the slow component of afterhyperpolarization (AHP) (Kohler et al., 1996). Here we examine whether rat type 2 S $K_{Ca}$ (rSK2) channels can affect the shape of the action potential and the neural firing pattern, by overexpressing rat SK2 channels in Aplysia neuron R15. Our results show that rSK2 overexpression decreased the intraburst frequency and changed the regular bursting activity of neurons to an irregular bursting or beating pattern in R15, Furthermore, the overexpression of rSK2 channels increased AHP and reduced the duration of the action potential. Thus, our results suggest that ectopic S $K_{Ca}$ channels play an important role in regulating the filing pattern and the shape of the action potential.ntial.

• Journal of Ginseng Research
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• 제19권1호
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• pp.31-38
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• 1995

Antioxidant effect of Korean ginseng (Panax ginseng C.A. Meyer) was investigated in rats. Long-term administration of ginseng water extract protected the activity of liver cytosotic SOD, catalase and glutathione peroxidase from being significantly decreased with advancing age (p<0.05). It was more effective toward glutathione peroxidase than other antioxidant enzymes. However, the level of sulfhydryl compounds and its related enzymes such as glutathione reductase and glutathione-5-transferase was not significantly changed by the administration of ginseng. Liver microsomal formation of reactive oxygen species such as superoxide and hydrogen peroxide did not show a significant difference between two groups although it was slightly decreased with age, but lipid peroxidizability of microsomal membrane induced by a prooxidant was slightly lower in ginseng-treated rats. Interestingly, antioxidant capacity of plasma from ginseng treated rats on autooxidation of ok-brain homogenates was much higher than that of normal ones. However, resistance of RBC membrane against oxidative stress showed a similar tendency. The content of serum TBA reactive substances lowered consistently in the rats treated with r ginseng at all corresponding age and a significant difference between two groups was found at 24 months of age (p<0.05). Ginseng extract protected lipid peroxidation in brain and liver. This protection was more effective in the stressed rats imposed by immobilization than normal ones. In conclusion, ginseng water extract protected the age related deterioration of major antioxidant enzymes, and this effect was more striking with increasing duration of treatment. This comprehensive antioxidant action of ginseng seems to be bra certain action of ginseng other than a direct antioxidant action, which might be a long term normalizing effect through the harmony of various components.

• The Korean Journal of Physiology
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• 제22권2호
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• pp.219-230
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• 1988

The effect of glycine, structurally the most simple amino acid was investigated on the electrophysiological characteristics of the isolated superfused atrial muscle and sinus node cells of the rabbit heart. Superfusion of the sinus node cell with glycine solution (3, 5 and 8 mM) produced concentration-dependent increments of OS (overshoot potential) and MDP (maximum diastolic potential). Generally action potential amplitude increased as a result of greater increment of OS than that of MDP. The changes in action potential of the sinus node cell peaked in $7{\sim}10{\;}minutes$ after onset of superfusioin. On the contrary to the response to intravenously administered glycine, the rate of spontaneous firing of sinus node cell was invariably increased following superfusion with glycine. Action potential duration manifested as $APD_{60}$ (time to 60% repolarization) was significantly shortened by glycine. And the electrophysiological effects of glycine on the atrial muscle cell were similar to that on the sinus node cells. The results of present study suggest that glycine can exert direct effects on the atrial muscle and sinus node cells of the rabbit heart.

• The Korean Journal of Physiology
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• 제29권2호
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• pp.203-216
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• 1995

The effects of ${\alpha}_1-adrenergic$ receptor stimulation on membrane potential, intracellular $Na^+$ activity, and twitch force were investigated in ventricular muscles from guinea-pig hearts. Action potentials, intracellular $Na^+$ activity, and twitch force of ventricular papillary muscles were measured simultaneously under various experimental conditions. Stimulation of the ${\alpha}_1-adrenergic$ receptor by phenylephrine produced variable changes in action potential duration, a slight hyperpolarization of the diastolic membrane potential, a decrease in intracellular $Na^+$ activity, and a biphasic inotropic response in which a transient negative inotropic response was followed by a sustained positive inotropic response. These changes were blocked by prazosin, an antagonist of the ${\alpha}_1-adrenergic$ receptor, but not by atenolol, an antagonist of the ${\beta}-adrenergic$ receptor. This indicates that the changes in membrane potential, intracellular $Na^+$ activity, and twitch force are mediated by stimulation of the ${\alpha}_1-adrenergic$ receptor, but not by stimulation of ${\beta}-adrenergic$ receptor. The decrease in intracellular $Na^+$ activity was not observed in quiescent muscles, depending on the rate of the action pontentials in beating muscles. The intracellular $Na^+$ activity decrease was substantially inhibited by tetrodotoxin. However, the decrease in intracellular $Na^+$ activity was not affected by an inhibition of the $Na^+-K^+$ pump. Therefore, the decrease in intracellular $Na^+$ activity mediated by the ${\alpha}_1-adrenergic$ receptor appears to be due to a reduction of $Na^+$ influx during the action potential, perhaps through tetrodotoxin sensitive $Na^+$ channels. Our study also revealed that the decrease in intracellular $Na^+$ activity might be related to the transient negative inotropic response. The intracellular $Na^+$ activity decrease could lower intracellular $Ca^{2+}$ through the $Na^+-Ca^{2+}$ exchanger and thereby produce a decline in twitch force.

• 대한수의학회지
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• 제23권2호
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• pp.193-198
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• 1983

A servey on bovine fascioliasis in 52,876 cattle of Euiseong, Andong, Yecheon, Wolseong areas in Gyeongbug Province was carried out by the intradermal test, and the clinical side action of the positive cattle administered with DS-6 intramuscularly was observed. In addition pathological examination of 2 cattle died with side action of DS-6 was also conducted. The results of the studies are summarized as follows; 1. The average infestation rate of bovine fascioliasis was 31.1% and regional infestation rates were 35.1% in Eiseong, 34.5% in Yecheon, 32.2% in Andong, 26.9% in Wolseong, respectively. 2. The side actions were occurred in 1.5%(115/7,667) cf cattle administered with DS-6 and the clinical observations were salivation, dyspnea, hyperamia of conjunctiva, lacrimation, perspiration, urticaria, tremor, diarrhea, staggering, convulsion, edema and abortion. 3. Within 1 hour after the injection, side actions were occurred in 61.7% of the 115 cattle while they were observed in 37.4% of the 115 catte from 1 hour to 2 hours post injection. 4. The duration of the side action was less than 2 hours in 29.5%, 2 to 10 hours in 47.0% and more than 10 hours in 23.5% of the 115 cattle. 5. Autopsy findings and histopathological observations indicate that the death of cattle is caused by anaphylactic shock.

• Biomolecules & Therapeutics
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• 제26권4호
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• pp.343-349
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• 2018

Although drugs such as barbiturates and benzodiazepines are often used for the treatment of insomnia, they are associated with various side effects such as habituations, tolerance and addiction. Alternatively, natural products with minimal unwanted effects have been preferred for the treatment of acute and/or mild insomnia, with additional benefits of overall health-promotion. Basic and clinical researches on the mechanisms of action of natural products have been carried out so far in insomnia treatments. Recent studies have been focusing on diverse chemical components available in natural products, with an interest of developing drugs that can improve sleep duration and quality. In the last 15 years, our co-workers have been actively looking for candidate substances from natural products that can relieve insomnia. This review is, therefore, intended to bring pharmacological data regarding to the effects of natural products on sleep duration and quality, mainly through the activation of $GABA_A$ receptors. It is imperative that phytochemicals will provide useful information during electroencephalography (EEG) analysis and serve as an alternative medications for insomnia patients who are reluctant to use conventional drugs.

• Journal of Preventive Medicine and Public Health
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• 제28권3호
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• pp.551-562
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• 1995

To assess the status of safety accidents, authors reviewed and analysed the records of safety accidents of a welding material manufacturing factory at Pohang city from January 1989 to December 1993. The results are; 1. The total incidence of safety accidents was 295 spells for five years. 2. Average age of workers with accident was 35.7 years. Average duration of employment was 6.2 years and the duration of employment increased as the year increased. 3. There was no statistical significance on season, month, weekday and time by year in the incidence of safety accidents. The most frequent part of body injured was upper extremities and the most frequent type of injury was abrasion. 4. Mean admission rate of safety accidents was 12.6% and the ratio of treated spells as occupational injury was 7.8%. 5. The most frequent cause of injury was worker's mistake and the most frequent action for the prevention of further accidents was safety education. 6. The incidence rate of safety accidents on 1993 was 116.2 spells per 1,000 persons. Above results suggest that to prevent safety accidents, safety education should be done continuously, the environmental and human factors were controlled and more exact reporting system of safety accidents was needed.