• The Korean Journal of Physiology and Pharmacology
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• v.17 no.2
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• pp.139-147
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• 2013

Lysolipids such as LPA, S1P and SPC have diverse biological activities including cell proliferation, differentiation, and migration. We investigated signaling pathways of LPA-induced contraction in feline esophageal smooth muscle cells. We used freshly isolated smooth muscle cells and permeabilized cells from cat esophagus to measure the length of cells. Maximal contraction occurred at $10^{-6}M$ and the response peaked at 30s. To identify LPA receptor subtypes in cells, western blot analysis was performed with antibodies to LPA receptor subtypes. LPA1 and LPA3 receptor were detected at 50 kDa and 44 kDa. LPA-induced contraction was almost completely blocked by LPA receptor (1/3) antagonist KI16425. Pertussis toxin (PTX) inhibited the contraction induced by LPA, suggesting that the contraction is mediated by a PTX-sensitive G protein. Phospholipase C (PLC) inhibitors U73122 and neomycin, and protein kinase C (PKC) inhibitor GF109203X also reduced the contraction. The PKC-mediated contraction may be isozyme-specific since only $PKC{\varepsilon}$ antibody inhibited the contraction. MEK inhibitor PD98059 and JNK inhibitor SP600125 blocked the contraction. However, there is no synergistic effect of PKC and MAPK on the LPA-induced contraction. In addition, RhoA inhibitor C3 exoenzyme and ROCK inhibitor Y27632 significantly, but not completely, reduced the contraction. The present study demonstrated that LPA-induced contraction seems to be mediated by LPA receptors (1/3), coupled to PTX-sensitive G protein, resulting in activation of PLC, PKC-${\varepsilon}$ pathway, which subsequently mediates activation of ERK and JNK. The data also suggest that RhoA/ROCK are involved in the LPA-induced contraction.

• The Korean Journal of Physiology
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• v.27 no.1
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• pp.27-35
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• 1993

Effects of the endothelium on the contractile responses to norepinephrine (NE) were investigated in isolated helical strips of the proximal and distal coronaries artery of pigs. The helical strips were immersed in Tris-buffered Tyrode's solution equilibrated with 100% $O_2$ at $35^{\circ}C$ and its isometric tension was measured. NE relaxed the strips precontracted with acetylcholine from both the proximal and distal coronary artery. NE-induced relaxation, which might be induced mainly by $\beta$-adrenoceptor function was dominant in the distal coronary arteries. NE-induced relaxation was converted to a contraction after $\beta$-adrenoceptor blockade with propranolol $(3{\times}10^{-6}M)$. ${\alpha}$-adrenoceptor-mediated contraction by NE was greater in the proximal coronary artery than the distal coronary artery. Quantitatively, ${\alpha}_1$-adrenoceptor mediated contraction by NE was greater than ${\alpha}_2$-adrenoceptor mediated contraction by NE in both arteries. NE-induced relaxation was decreased by rubbing of endothelium in both arteries. ${\alpha}_1-and\;{\alpha}_2$-adrenoceptor mediated contraction by NE were potentiated by rubbing of endothelium in both arteries. Pretreatment with methylene blue, an inhibitor of soluble guanylate cyclase, increased ${\alpha}_1-\;and\;{\alpha}_2$-adrenoceptor mediated contraction by NE in both arteries with endothelium. From the above results, we suggest that the effect of activation of $\alpha$-adrenoceptors by NE may be modulated by endothelium in the proximal and distal coronary arteries of pigs. This effect may be mediated via endothelium derived relaxing factor.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.3
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• pp.257-262
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• 2015

It is well known that cigarette smoke can cause erectile dysfunction by affecting the penile vascular system. However, the exact effects of nicotine on the corpus cavernosum remains poorly understood. Nicotine has been reported to cause relaxation of the corpus cavernosum; it has also been reported to cause both contraction and relaxation. Therefore, high concentrations of nicotine were studied in strips from the rabbit corpus cavernosum to better understand its effects. The proximal penile corpus cavernosal strips from male rabbits weighing approximately 4 kg were used in organ bath studies. Nicotine in high concentrations ($10^{-5}{\sim}10^{-4}M$) produced dose-dependent contractions of the corpus cavernosal strips. The incubation with $10^{-5}M$ hexamethonium (nicotinic receptor antagonist) significantly inhibited the magnitude of the nicotine associated contractions. The nicotine-induced contractions were not only significantly inhibited by pretreatment with $10^{-5}M$ indomethacin (nonspecific cyclooxygenase inhibitor) and with $10^{-6}M$ NS-398 (selective cyclooxygenase inhibitor), but also with $10^{-6}M$ Y-27632 (Rho kinase inhibitor). Ozagrel (thromboxane $A_2$ synthase inhibitor) and SQ-29548 (highly selective TP receptor antagonist) pretreatments significantly reduced the nicotine-induced contractile amplitude of the strips. High concentrations of nicotine caused contraction of isolated rabbit corpus cavernosal strips. This contraction appeared to be mediated by activation of nicotinic receptors. Rho-kinase and cyclooxygenase pathways, especially cyclooxygenase-2 and thromboxane $A_2$, might play a pivotal role in the mechanism associated with nicotine-induced contraction of the rabbit corpus cavernosum.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.4
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• pp.1107-1110
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• 2004

The purpose of this research was to investigate the effects of supercritical fluid extract of Kamichungbieum (SFE) on the contraction of isolated rat aorta. The contractile force of rat aorta was measured with force displacement transducer under 1.5g loading tension. The contraction of aorta induced by phenylephrine 0.1 μM was inhibited by SFE. The aorta relaxed by SFE was inhibited by the pretreatment of L-NNA, ODQ or indomethacin, respectively. These results indicate that SFE induce the relaxation of isolated aorta via activation of nitric oxide, cAMP and cyclooxygenase in epithelium cells.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.3 no.1
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• pp.1-15
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• 1990

Aebaegeum has been widely used in the treatment of epistaxis, as based on Oriental Medical 1iteratures. In order to investigate experimentally the clinical effects of Aebaegeum, hemostatic time, plasma recalcification time and prothrombin time of hypoprothrombinemia induced by warfarin injection, action on isolated ileum, action on blood vessel, action on blood pressure and respiration and action on heart were observed. The result of the studies were obtained as follows: 1. Hemostatic time of vein ruptured mice was significantly shortened. 2. Plasma recalification time and prothrombin time of hypoprothrombinemic rats induced by warfarin injection were significantly shortened. 3. Spontaneous mobilities in the isolated ileum of mice were significantly suppressed, and contraction by acetylcholine chloride and barium chloride were inhibited. 4. Dilatation of blood vessel and downing of blood pressure of rabbit were noted. 5. Contraction of heart in the original position and isolated heart of frog were significantly shortened. According to the above result, it is expected that Aebaegeum can be widely applicable to the treatment of epistaxis.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.2
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• pp.193-199
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• 1998

To elucidate the mechanism involved in the cerebral vascular spasm following subarachnoid hemorrhage (SAH), the effects of the cerebrospinal fluid (CSF) obtained from the SAH patients on the resting tension and its influence on the contractile responses to various vasoactive agents and to hypoxia were investigated in isolated porcine cerebral arteries. All the CSFs containing hemoglobin (Hb) produced contraction and some Hb-free CSFs also elicited contraction. When the Hb-free CSF was separated by microfilter, the filtrate of ＜30,000 MW did not produce contraction, while the fraction above 30,000 MW elicited more marked contractile responses than the unfractionated CSF. The CSF contraction was significantly attenuated in the presence of indomethacin or nimodipine, whereas the contractions induced by KCl, prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$), or endothelin-1 (ET-1) were not affected by the CSF pretreatment. However, the contractile responses induced by 5-hydroxytryptamine (5-HT) and phenylephrine (PE) were markedly potentiated by the pretreatment. Hypoxia-induced vasoconstriction was significantly potentiated by the pretreatment with either unfractionated CSF or the CSF fraction of above 30,000 MW. These results suggest that unknown vasocontractile substance(s) exists in the Hb-free CSF and that the substance, with its MW above 30,000, is activated by hypoxia and acts synergistically with 5-HT and PE, and that extracellular calcium influx and cyclooxygenase are also involved in the cerebral vasoconstrictory effect of Hb-free CSF.

• Journal of Life Science
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• v.10 no.6
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• pp.584-590
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• 2000

Natural products are one of the useful source of cardiovascular drugs, in particular, when they have antioxidant activity. Gagaminine, an alkaloid isolated from the roots of Cynanchum wilfordi Hemsley, has been reported to potently inhibit the aldehyde oxidase activity ({TEX}$IC_{50}${/TEX}=0.8$\mu$M) and reduce lipid peroxidation. However, the effect of gagaminine on vascular smooth muscle has not yet been investigated. In the present study, we examined whether gagaminine relaxes vascular smooth muscle by isometric tension study. In order to observe its relaxation effect on the arteries, conductivel vessel (rat thoracic aorta) and resistance vessel (pig coronary artery) were purposely used. Results indicated that gagaminine relaxed in a concentration-dependent manner $\alpha$-adrenoceptor agonist, phenylephrine (PE)-induced contraction of rat aorta. Pretreatment with gagaminine inhibited PE-induced contraction, noncompetitively. {TEX}$Ca^{2+}${/TEX}-induced contraction was significantly diminished by gagaminine. In pig coronary artery, gagaminine relaxed thromboxane receptor (U 46619)-mediated contraction in dose-dependent manner. Pretreatment with gagaminine also reduced the maximum contraction induced by KCl. These observations strongly suggest that agagminnine relaxes vascular smooth muscle, irrespective of both resistance and conductive artery. We demonstrate that gagaminine, a potent natural antioxidant, has a significant vasodilatory effect and its action mechanism van be ascribed at least in part to {TEX}$Ca^{2+}${/TEX} antagonistic action as evidenced by inhibition {TEX}$Ca^{2+}${/TEX}-induced contraction (rat aorta) and KCl-induced contraction (porcine artery). Furthermore, neither $\alpha$ -adrenoceptor nor thromboxane receptor seems responsible for the relaxation of gagaminine.

• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.359-381
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• 1992

This study was designed to investigate the effect of diazepam on the spontaneous contraction and oxytocin induced contraction of the isolated rat uterus. Female rat(Sprague-Dawley) pretreated with oophorectomy and 4 days administration of estrogen, weighing about 200 g, was sacrificed by cervical dislocation, and the uteruses were isolated. A longitudinal muscle strip was placed in temperature controlled($37^{\circ}C$) muscle chamber containing Locke's solution and myographied isometrically. Diazepam inhibited the spontaneous contraction and oxytocin induced contraction of the isolated rat uterus in a concentration-dependent manner. GABA, muscimol, a GABA A receptor agonist, bicuculline, a competitive GAGA A receptor antagonist, picrotoxin, a non competitive GABA A receptor antagonist, baclofen, a GABA B receptor agonist, and delta-aminovaleric acid, a GABA B receptor antagonist, did not affect on the spontaneous and oxytocin induced contraction of the isolated rat uterus. The inhibitory actions of diazepam on the spontaneous and oxytocin induced contraction were not affected by all the GABA receptor agonists and antagonists, but exceptionally potentiated by bicuculline. This potentiation-effect by bicuculline was not antagonized by muscimol. In normal calcium PSS, addition of calcium restored the spontaneous contraction preinhibited by diazepam and recovered the contractile of oxytocin preinhibited by diazepam. A23187, a calcium inophore, enhanced the restoration of both the spontaneous and oxytocin induced contraction by addition of calcium. In calcium-free PSS, diazepam suppressed the restoration of spontaneous motility by addition of calcium but allowed the recovery of spontaneous motility to a considerable extent. Diazepam could not inhibit some development of contractility by oxytocin in calcium-free PSS, but inhibited the increase in contractility by subsequent addition of calcium. These results suggest that the inhibitory action of diazepam on the rat uterine motility does not depend on or related to GABA receptors and that diazepam inhibits the extracellular calcium influx to suppress the spontaneous and oxytocin induced contractilities.

• Journal of Chest Surgery
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• v.24 no.7
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• pp.637-646
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• 1991

Effect of noradrenaline and endothelium on the high K+ or Ach-induced contraction were investigated in the pig myocardial coronary artery. The helical strip of isolated pig myocardial coronary artery was immersed in the Tris-buffered Tyrode`s solution equilibrated with 100% O2 at 37oC and its isometric tension was measured. High K+ and Ach-induced contraction were dose-dependent. By denuding the endothelium, dose-contraction curve of K+ was not shifted significantly to the left and upward, but that of Ach was shifted significantly to same direction 25 mM K+ - and Ach-induced contraction were relaxed by norepinephrine[NE]. NE-induced relaxation was blocked by the pretreatment of propranolol, which was known as b-adrenoceptor blocker. And, phenylephrine known as a-adrenoceptor agonist, and clonidine known as a-adrenoceptor agonist increased the 25mM K+ - induced contraction respectively. Denuding of endothelium did not show any significant effects on NE-induced relaxation and contraction increased by phenylephrine and clonidine. Tyramine increased 25mM K+ - induced contraction further. The contractile response by tyramine on the 25mM K+ - induced contraction was not blocked by the pretreatment of phentolamine, but was partially blocked by the pretreatment of atropine. From the above results, it is suggested that activation of a1-and a2-adrenoceptors induce the contraction, activation of b-adrenoceptors induce the relaxation, and NE-induced relaxation is mainly due to activation of b-adrenoceptors. Also it is suggested that denudation of endothelium did not influence NE-induced relaxation, but influence Ach-induced contraction in the pig myocardial coronary artery.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.19-24
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• 1989

To elucidate the physiological characteristics of histamine receptor of the isolated renal artery in dog, effects of various receptor blockers and $Ca^{{+}{+}}$ channel blockers on the contractile responses of histamine were investigated in the isolated renal artery of dog. The results were summarized as follows: 1. Histamine caused the contraction in the isolated renal artery of dog, and the contractile responses increased between the concentration of $5{\times}10^{-6}M$ and $10^{-2}M$ in dose-dependent manner. 2. The contractile response induced by histamine ($10^{-3}M$) was not blocked by pretreatment with atropine ($10^{-6}M$), phentolamine ($10^{-6}M$), propranolol ($10^{-6}M$) or cimetidine ($10^{-6}M$), but was completely blocked by pretreatment with pyrilamine ($10^{-6}M$). 3. The contractility induced by histamine ($10^{-3}M$) was decreased in the $Ca^{{+}{+}}$ free medium. 4. The contractile response induced by histamine ($10^{-3}M$) was markedly inhibited by pretreatment with papaverine ($5{\times}10^{-5}M$) or verapamil ($5{\times}10^{-5}M$). 5. After the pre-contraction induced by norepinephrine ($10^{-7}M$) or prostaglandin $F2{\alpha}$ ($5{\times}10^{-6}M$), the contractile response induced by the additional treatment of histamine ($10^{-3}M$) was markedly increased compared with that of histamine ($10^{-3}M$) alone.