• The Korean Journal of Physiology and Pharmacology
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• 제13권1호
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• pp.27-32
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• 2009

The effects of oxidized low-density lipoprotein(OxLDL) and its major lipid constituent lysophosphatidylcholine(LPC) on $Ca^{2+}$ entry were investigated in cultured human umbilical endothelial cells(HUVECs) using fura-2 fluorescence and patch-clamp methods. OxLDL or LPC increased intracellular $Ca^{2+}$ concentration($[Ca^{2+}]_i$), and the increase of $[Ca^{2+}]_i$ by OxLDL or by LPC was inhibited by $La^{3+}$ or heparin. LPC failed to increase $[Ca^{2+}]_i$ in the presence of an antioxidant tempol. In addition, store-operated $Ca^{2+}$ entry(SOC), which was evoked by intracellular $Ca^{2+}$ store depletion in $Ca^{2+}$-free solution using the sarcoplasmic reticulum $Ca^{2+}$ pump blocker, 2, 5-di-t-butyl-l,4-benzohydroquinone(BHQ), was further enhanced by OxLDL or by LPC. Increased SOC by OxLDL or by LPC was inhibited by U73122. In voltage-clamped cells, OxLDL or LPC increased $[Ca^{2+}]_i$ and simultaneously activated non-selective cation(NSC) currents. LPC-induced NSC currents were inhibited by 2-APB, $La^{3+}$ or U73122, and NSC currents were not activated by LPC in the presence of tempol. Furthermore, in voltage-clamped HUVECs, OxLDL enhanced SOC and evoked outward currents simultaneously. Clamping intracellular $Ca^{2+}$ to 1 ${\mu}M$ activated large-conductance $Ca^{2+}$-activated $K^+(BK_{ca})$ current spontaneously, and this activated $BK_{ca}$ current was further enhanced by OxLDL or by LPC. From these results, we concluded that OxLDL or its main component LPC activates $Ca^{2+}$-permeable $Ca^{2+}$-activated NSC current and $BK_{ca}$ current simultaneously, thereby increasing SOC.

• The Korean Journal of Physiology and Pharmacology
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• 제13권6호
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• pp.437-442
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• 2009

A non-steroidal anti-inflammatory drug (NSAID) has many adverse effects including cardiovascular (CV) risk. Diclofenac among the nonselective NSAIDs has the highest CV risk such as congestive heart failure, which resulted commonly from the impaired cardiac pumping due to a disrupted excitationcontraction (E-C) coupling. We investigated the effects of diclofenac on the L-type calcium channels which are essential to the E-C coupling at the level of single ventricular myocytes isolated from neonatal rat heart, using the whole-cell voltage-clamp technique. Only diclofenac of three NSAIDs, including naproxen and ibuprofen, significantly reduced inward whole cell currents. At concentrations higher than $3\;{\mu}M$, diclofenac inhibited reversibly the $Na^+$ current and did irreversibly the L-type $Ca^{2+}$ channels-mediated inward current $(IC_{50}=12.89\pm0.43\;{\mu}M)$ in a dose-dependent manner. However, nifedipine, a well-known L-type channel blocker, effectively inhibited the L-type $Ca^{2+}$ currents but not the $Na^+$ current. Our finding may explain that diclofenac causes the CV risk by the inhibition of L-type $Ca^{2+}$ channel, leading to the impairment of E-C coupling in cardiac myocytes.

• The Korean Journal of Physiology
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• 제23권1호
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• pp.99-108
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• 1989

The effects of prostaglandin $(PGF_{2{\alpha}})$ on the contractility of vascular smooth muscle were investigated in the helical strip of the rabbit aorta. The aortic strip was immersed in the phosphate-buffered Tyrode's solution which was equilibrated with 100% $O_{2}$ at $35^{\circ}C$ and its isometric tension was measured. The contraction was induced by $(PGF_{2{\alpha}})$, norepinephrine (NE), or potassium (40 mM) in the nomal Tyrode's solution (1 mM, $Ca^{2+}$) or $Ca^{2+}-free$ Tyrode's solution. Effects of verapamil and phentolamine on the contraction were also observed. The aortic strip began to contract at the concentration of $5\;{\mu}g%$ and reached the maximal contraction at the concentration of $150\;{\mu}g%$ $(PGF_{2{\alpha}})$. The maximal contraction was corresponded respectively to $52.2{\pm}3.0%$ and $81.5{\pm}3.5%$ of maximal contraction by NE $(1{\times}10^{-5}M)$ and 40 mM $K^{+}$. And the maximal contractions by $(PGF_{2{\alpha}})$ or NE were induced at the concentration of about 1 mM $Ca^{2+}$. $(PGF_{2{\alpha}})$ induced the contraction of aortic strip even after induction of contraction by 40 mM $K^{+}$ and the contraction by $(PGF_{2{\alpha}})$ was not blocked by the ${\alpha}-receptor$ blocker, phentolamine. And the contraction by the $(PGF_{2{\alpha}})$ was inhibited partially by a verapamil at the concentration of $1{\times}10^{-5}M$ and the contraction began to increase at the concentration of $1{\times}10^{-4}M$ verapamil. Whereas the contraction by NE was completely blocked by verapamil. Though both the $(PGF_{2{\alpha}})$ and NE induced the contraction in the $Ca^{2+}-free$ Tyrode's solution, the peak tension was not maintained. But the rate of tension decline was lower in the contraction by $(PGF_{2{\alpha}})$ than in that by NE. The verapamil did not inhibit the contraction by $(PGF_{2{\alpha}})$ in the $Ca^{2+}-free$ Tyrode's solution and increased the contraction at the concentration of above $1{\times}10^{-4}M$. The NE-induced contraction in the $Ca^{2+}-free$ Tyrode's solution was inhibited completely by a verapamil. From the above results it is suggested that the contraction induced by $(PGF_{2{\alpha}})$ results from the promotion of the both $Ca^{2+}$ influx and the intracellular $Ca^{2+}$ release by different way from NE.

• YAKHAK HOEJI
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• 제38권2호
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• pp.149-157
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• 1994

The role of nitric oxide(NO) as neurotransmitter in non-adrenergic non-cholinergic (NANC) relaxation induced by electrical stimulation has been studied in circular muscle strips of the rabbit gastric fundus. In the presence of atropine and guanethidine, low frequency$(1{\sim}20\;Hz)$ and short trains (5s) of electrical stimulation induced the frequency-dependent relaxations which were not affected by adrenergic and cholinergic blockage, but abolished by tetrodotoxin, a nerve conductance blocker. L-NNA, a stereospecific inhibitor of NO biosynthesis, inhibited the relaxations induced by electrical stimulation but not affected the relaxation to exogenous NO. The effect of L-NNA was prevented by L-arginine, the precursor of the NO biosynthesis, but not by its enantiomer, D-arginine. Exogenous administration of NO$(10{\sim}100\;{\mu}M)$ caused the concentration-dependent relaxation which showed a similarity to those obtained with electrical stimulation. Hemoglobin, a NO scavenger, abolished the NO-induced relaxations and also markedly inhibited those evoked by electrical stimulation. Application of adenosine triphosphate$(1{\sim}10\;{\mu}M)$ induced concentration-independent contractions, but in high dose caused temporary contraction followed by relaxation which was not affected by L-NNA. Exogenous vasoactive intestinal polypeptide$(10{\sim}100\;nM)$ induced the concentration-dependent relaxation, while its effects were slower in onset and more persistent than those induced by short trains and low frequencies of electrical stimulation. Based on above results, it is suggested that NO is the principal neurotransmitter of NANC nerve at relaxation induced by short trains and low frequencies of electrical stimulation in the rabbit gastric fundus.

• Journal of the korean academy of Pediatric Dentistry
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• 제31권1호
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• pp.19-25
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• 2004

Dentally disabled person means one who have difficulty in cooperating voluntarily with a dentist for routine dental care. Seoul National University Dental Hospital (SNUDH) Dental Clinic for Disabled has worked for them under outpatient anesthesia concept. The aim of this study was to determine the anesthetic characteristics of the patients attending for dental treatment at SNUDH Dental Clinic for Disabled in order to establish better future treatment plans. The data were drawn from the patients who visited SNUDH Dental Clinic for Disabled from January 1999 to October 2002. Total 93 dental treatments for 83 patients were enrolled in this study. Most patients had mental retardation and the conservative treatments were carried out under general anesthesia. Thiopental and vecuronium were mostly used for induction agent and neuromuscular blocker, respectively. Enflurane, with oxygen and nitrous oxide, was mostly used to maintain the anesthesia. Mean total anesthetic time was $164.4{\pm}57.2$ minutes and mean duration at the post-anesthetic care unit was $106.2{\pm}50.5$ min. Serious postoperative complications were not observed. These results showed our successful anesthetic outcomes without any severe side effect or complication and the needs of more outpatient centers for dental care for disabled.

• International Journal of Oral Biology
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• 제32권2호
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• pp.51-57
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• 2007

Cyclosporin A (CsA) plays an important role in clinical medicine and basic biology as an immunosuppressant and a mitochondrial permeability blocker, respectively. It was reported that CsA has a protective role by preventing apoptosis and promoting the proliferation in severed neurons. However, the molecular mechanisms for CsA-induced neuronal cell proliferation are unclear. In this study, we examined the mechanisms underlying the CsA-induced proliferation of PC12 cells. CsA increased the viability of PC12 cells in a dose(over $0.1{\sim}10\;{\mu}M$)-and time-dependent manner. The level of ROS generation was decreased in the CsA-treated PC12 cells. Expression of Bcl-2, an antiapoptotic molecule that inhibits the release of cytochrome c from the mitochondria into the cytosol, was upregulated, whereas Bax, a proapototic molecule, was not changed in the CsA-treated PC12 cells. CsA downregulated the mRNA expression of VDAC 1 and VDAC 3, but VDAC 2 was not changed in the CsA-treated PC12 cells. The level of cytosolic cytochrome c released from the mitochondria and the caspase-3 activity were attenuated in the CsA-treated PC12 cells. These results suggest that the mitochondria-mediated apoptotic signal and Bcl-2 family may play an important role in CsA-induced proliferation in PC12 cells.

• Animal cells and systems
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• 제2권4호
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• pp.483-488
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• 1998

We previously found that a potent gonadotropin-releasing hormone (GnRH) agonist, buserelin, decreases GnRH promoter activity together with GnRH mRNA level, providing evidence for an autoregulatory mechanism operating at the level of GnRH gene transcription in immortalized GT1-1 neuronal cells. To examine whether agonist-induced decrease in GnRH mRNA level requires the continuous presence of buserelin, we performed a pulse-chase experiment of buserelin treatment. Short-term exposure (15 min) of GT1-1 neuronal cells to buserelin ($10{\mu}M$) was able to decrease GnRH mRNA levels when determined 24 h later. When GT1-1 cells were treated with buserelin ( $10{\mu}M$) for 30 min and then incubated for 1, 3, 6, 12, 24, and 48 h after buserelin removal, a significant decrease in GnRH mRNA levels was observed after the 12 h incubation period. These data indicate that inhibitory signaling upon buserelin treatment may occur rapidly, but requires a long time (at least 12 h) to significantly decrease the GnRH mRNA level. To examine the possible involvement of de novo synthesis and/or mRNA stability in buserelin-induced decrease in GnRH gene expression, actinomycin D ($5{\mu}m/ml$), a potent RNA synthesis blocker, was co-treated with buserelin. Actinomycin D alone failed to alter basal GnRH mRNA Revel, but blocked the buserelin-induced decrease in GnRH mRNA level at 12 h of post-treatment. These data suggest that buserelin may exert its inhibitory action by altering the stability of GnRH mRNA. Moreover, a polvsomal RNA separation by sucrose gradient centrifugation demonstrated that buserelin decreased the translational efficiency of the transcribed GnRH mRNA. Taken together, these results clearly indicate that GnRH agonist buserelin acts as an inhibitory signal at multiple levels such as transcription mRNA stability, and translation.

• YAKHAK HOEJI
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• 제34권4호
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• pp.224-237
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• 1990

A single uniform population of specific, saturable, high affinity binding site of $[^3H]QNB$ guinuclidinyl benzilate(QNB) was identified in the rat cerebral microsomes. The Kd value(37.2 pM) for $[^3H]QNB$ calculated from the kinetically derived rate constants was in agreement with the Kd value(48.9 pM) determined by analysis of saturation isotherms at various receptor concentrations. Dimenhydrinate(DMH), histamine $H_1-blocker$, increased Kd value for $[^3H]QNB$ QNB without affecting the binding site concentrations and this effect resulted from the ability of DMH to slow $[^3H]QNB-receptor$ association. Pirenzepine inhibition curve of $[^3H]QNB$ binding was shallow(nH = 0.52) indicating the presence of two receptor subtypes with high ($M_1-site$) and low($M_2-site$) affinity for pirenzepine. Analysis of these inhibition curves yielded that 68% of the total receptor populations were of the $M_1-subtype$ and the remaining 32% of the $M_2-subtype$. Ki values for the $M_1-$ and $M_2-subtypes$ were 2.42 nM and 629.3 nM, respectively. Ki values for $H_1-blockers$ that inhibited $[^3H]QNB$ binding varied with a wide range ($0.02-2.5\;{\mu}M$). The Pseudo-Hill coefficients for inhibition of $[^3H]QNB$ binding by most of $H_1-blockers$ examined except for oxomemazine inhibition of $[^3H]QNB$ binding were close to one. The inhibition curve for oxomemazine in competition with $[^3H]QNB$ was shallow(nH = 0.74) indicating the presence of two receptor populations with different affinities for this drug. The proportion of high and low affinity was 33:67. The Ki values for oxomemazine were $0.045{\pm}0.016\;{\mu}M$ for high affinity and $1.145{\pm}0.232\;{\mu}M$ for low affinity sites. These data indicate that muscarinic receptor blocking potency of $H_1-blockers$ varies widely between different drugs and that most of $H_1-blockers$ examined are nonselective antagonist for the muscarinic receptor subtypes, whereas oxomemazine might be capable of distinguishing between subclasses of muscarinic receptor.

• Journal of Veterinary Clinics
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• 제32권1호
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• pp.9-15
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• 2015

Purpose of this study is to determine the reasonable portal approach for thoracoscopic right middle lung lobectomy in small sized dogs under 10 kg. Ten healthy beagle dogs weighing $8.67{\pm}0.49kg$ were included. Under general anesthesia, one-lung ventilation (1LV) was achieved using endobronchial blocker with guidance of fiber-optic bronchoscope. Two portal approaches were used; 8-6-10 intercostal space (ICS) and 8-6-5 ICS approach. Thoracoscopic right middle lung lobectomy was performed using endoscopic linear self-cutting stapler and specimen retrieval bag. Each approach was evaluated by scoring 0; bad, 1; endurable, 2; good, 3; excellent in following five category, 1) visualization, 2) triangulation; instrumental sword fighting in the thoracic cavity, 3) approach to hilar pedicle; application of stapler, 4) any obstacles in applicating Lap Bag, and 5) the operator's convenience. Favorable working space was secured by 1LV and thoracoscopic right middle lung lobectomy was successfully completed in all dogs. There was no need to change the portal location and iatrogenic complication. Most of scores were good to excellent in both approaches. Consequently, both approaches are feasible methods for thoracoscopic right middle lung lobectomy with one lung ventilation using endoscopic linear self-cutting stapler in dogs weighing less than 10 kg.

• Journal of Yeungnam Medical Science
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• 제8권2호
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• pp.95-105
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• 1991

This study was designed to investigate the effect of GABA and related substances on the spontaneous contraction of rat small intestine. The rats(Sprague-Dawley), weighing 200-250g, were sacrificed by cervical dislocation, and the small intestine was isolated. Longitudinal muscle strips from duodenum, jejunum and ileum were suspended in Biancani's isolated muscle chambers and myographied isometrically. GABA and muscimol, a GABA A receptor agonist relaxed the duodenum and jejunum significantly, but baclofen-induced relaxation in those muscle strips was negligible. The effectiveness of GABA and muscimol in various regions were the greatest on duodenum, and greater on jejunum than on ileum The effect of GABA and muscimol was antagonized by bicuculline, a compeptitive GABA A receptor antagonist and picrotoxin, a noncomptitive GABA A receptor antagonist. Duodenal relaxation induced by GABA and muscimol was unaffected by hexamethonium, but was prevented by tetrodotoxin. These results suggest that GABA inhibit the contractility of smooth muscle with distinct regional difference of efficacy, and the site of inhibitory action is the GABA A receptor existing at the presynaptic membrane of postganglionic excitatory nerves.