Characteristics of Spontaneous Contraction in the Circular Smooth Muscles of Cat Ileum

Sun Young Park,제현동,Jae Ho Shim,손의동 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.1

We investigated the characteristics of spontaneous contraction in feline ileal circular smooth. Smooth muscle contractions were recorded by an isometric force transducer. The neurotoxin tetrodotoxin did not alter the spontaneous contraction of the circular muscles. Atropine or guanethidine also did not affect on the contraction. In Ca2+-free Krebs, the spontaneous contraction completely disappeared in the muscles. An L-type Ca2+ channel blockade with nimodipine decreased the amplitude of spontaneous contraction. A selective inhibitor of the sarcoplasmic reticulum Ca2+-ATPase, thapsigargin, had not no effect on spontaneous contraction within incubation time for 10min. However, phosphoinositide-specific phopholipase C inhibitor, U-73122, decreased the frequency of the contraction in circular smooth muscle These results suggest that the neuronal component, adrenergic or cholinergic innervation was not involved in spontaneous activity and that extracellular Ca2+ influx via an L-type Ca2+ channel may mediate the contractile amplitude in circular smooth muscles of cat ileum.

The Inhibitory Effect of Rosiglitazone on Agonist-Induced or Spontaneous Regulation of Contractility

제현동,Sun Young Park,Amy L. Barber,손의동 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.4

The present study was undertaken to determine whether rosiglitazone treatment influences on the agonist-induced or spontaneous regulation of vascular smooth muscle contraction and, if so, to investigate the related mechanism. Stimulants were directly added without any preanesthetic stress or spontaneous vasoconstriction was induced by preanesthetic physical stress where rat aortic ring preparations isolated from rat exposed to preanesthetic stress such as pinch or prick for 30 min were mounted in organ baths and then exposed to contractile agents. Previously and subchronically ingested rosiglitazone decreased Rho-kinase activating agonistinduced contraction but not depolarization- or α adrenergic agonist-induced contraction. Moreover, preanesthetic stress induced the stress-induced spontaneous contraction and previously and subchronically ingested rosiglitazone abolished the stress-induced spontaneous contraction. In conclusion, this study provides the evidence and possible related mechanism concerning the vasorelaxing effect of an antidiabetic rosiglitazone as an antihypertensive on the agonist-induced contraction or stress-induced spontaneous vasoconstriction in rat aortic rings regardless of endothelial function.

The Inhibitory Effect of Rosiglitazone on Agonist-Induced or Spontaneous Regulation of Contractility

Park, Sun-Young,Barber, Amy L.,Sohn, Uy-Dong,Je, Hyun-Dong 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.4

The present study was undertaker to determine whether rosiglitazone treatment influences on the agonist-induced or spontaneous regulation of vascular smooth muscle contraction and, if so, to investigate the related mechanism. Stimulants were directly added without any preanesthetic stress or spontaneous vasoconstriction was induced by preanesthetic Physical stress where rat aortic ring preparations isolated from rat exposed to preanesthetic stress such as pinch or prick for 30 min were mounted in organ baths and then exposed to contractile agents. Previously and subchronically ingested rosiglitazone decreased Rho-kinase activating agonist-induced contraction but not depolarization- or ${\alpha}$ adrenergic agonist-induced contraction. Moreover, preanesthetic stress induced the stress-induced spontaneous contraction and previously and subchronically ingested rosiglitazone abolished the stress-induced spontaneous contraction. In conclusion, this study provides the evidence and possible related mechanism concerning the vasorelaxing effect go an antidiabetic rosiglitazone as an antihypertensive on the agonist-induced contraction or stress-induced spontaneous vasoconstriction in rat aortic rings regardless of endothelial function.

Spontaneous Contractions Augmented by Cholinergic and Adrenergic Systems in the Human Ureter

Lee, Hyun-Woo,Baak, Cheol-Hee,Lee, Moo-Yeol,Kim, Young-Chul The Korean Society of Pharmacology 2011 The Korean Journal of Physiology & Pharmacology Vol.15 No.1

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3~4 times within 5 minutes in the longitudinal group. ACh ($10^{-4}\;M$) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of $10^{-5}\;M$ glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.

Spontaneous Contractions Augmented by Cholinergic and Adrenergic Systems in the Human Ureter

이현우,Cheol Hee Baak,이무열,김영철 대한약리학회 2011 The Korean Journal of Physiology & Pharmacology Vol.15 No.1

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3∼4 times within 5 minutes in the longitudinal group. ACh (10−4 M) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of 10−5 M glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.

Spontaneous Contractions Augmented by Cholinergic and Adrenergic Systems in the Human Ureter

Hyun Woo Lee,Cheol Hee Baak,Moo Yeol Lee,Young Chul Kim 대한생리학회-대한약리학회 2011 The Korean Journal of Physiology & Pharmacology Vol.15 No.1

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3∼4 times within 5 minutes in the longitudinal group. ACh (10⁻⁴ M) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of 10⁻⁵ M glibenclamide. Receptor tyrosine kinase (<i>c-kit</i>) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.

The Contractile and Electrical Responses of Guinea-pig's Gastric Smooth Muscle to Serotonin

Lee, Sang-Jin,Hwang, Sang-Ik,Kim, Ki-Whan The Korean Physiological Society 1991 대한생리학회지 Vol.25 No.2

In order to elucidate systematically the effects of serotonin on gastric motility of guinea-pig, the contractile and electrical responses to serotonin were recorded using four kinds of muscle strips prepared from antral circular, antral longitudinal, fundic circular, and fundic longitudinal muscles. Experiments were performed using various methods including isometric contraction recording, transmural electrical field stimulation, junction potential recording, intracellular microelectrode technique, and partition stimulation method. The results were as follows: 1) The effect of serotonin on spontaneous contractions was inhibitory in the circular muscle strips of the antrum and fundus, while it was excitatory in the longitudinal muscle strips of the antrum and fundus. Serotonin changed mainly phasic contractions of both the circular and longitudinal muscle strips in the antrum, while it changed mainly tonic contractions of both the circular and longitudinal muscle strips in the fundus. 2) On the contractions induced by transmural nerve stimulation, serotonin decreased the amplitude in the circular muscle strips of the antrum, but it increased them in the other three groups of muscle strips(antral longitudinal, fundic circular, and fundic longitudinal). 3) On the contractions induced by direct muscle stimulation, serotonin decreased the amplitude in the circular muscle strips of the antrum and fundus. 4) In the fundic circular muscle strips serotonin potentiated excitatory junction potentials (EJPs), and in the antral circular muscle strips it evoked EJPs after inhibitory junction potentials(IJPS). 5) In the antral circular muscle strips serotonin did not affect the slow wave even at the disappearance of spontaneous contractions. On the contrary it increased the amplitude of the slow wave, when the spike component was potentiated and the second component was inhibited. 6) In the antral circular muscle strips the membrane potential was slightly hyperpolarized, but the membrane resistance was not changed. From the above results following conclusions could be made. 1) Serotonin inhibits spontaneous contractions of the circular muscle layer and it increases those of the longitudinal one, irrespective of the gastric region. 2) In the guinea-pig stomach there exists a serotoninergic facilitatory neuromodulation system which exerts its effect on cholinergically mediated contraction. 3) The excitation-contraction decoupling was observed in the effect of serotonin.

Neurotensin Enhances Gastric Motility in Antral Circular Muscle Strip of Guinea-pig

Tae Yong Koh,Sung Joon Kim,Sang Jin Lee,Tong Mook Kang,Jae Yeoul Jun,Jae Hoon Sim,Insuk So,Ki Whan Kim 대한생리학회-대한약리학회 2000 The Korean Journal of Physiology & Pharmacology Vol.4 No.3

<P> Many reports suggest that neurotensin (NT) in the gastrointestinal tract may play a possible role as a neurotransmitter, a circulating hormone, or a modulator of motor activity. NT exerts various actions in the intestine; it produces contractile and relaxant responses in intestinal smooth muscle. This study was designed to investigate the effect of NT on motility of antral circular muscle strips in guinea-pig stomach. To assess the role of Ca<SUP>2⁢</SUP> influx in underlying mechanism, slow waves were simultaneously recorded with spontaneous contractions using conventional intracellular microelectrode technique. At the concentration of 10<SUP>⁣7</SUP> M, where NT showed maximum response, NT enhanced the magnitude (863⁑198%, mean⁑SEM, n=13) and the frequency (154⁑10.3%, n=11) of spontaneous contractions. NT evoked a slight hyperpolarization of membrane potential, tall and steep slow waves with abortive spikes (278⁑50%, n=4). These effects were not affected by atropine (2μM), guanethidine (2μM) and tetrodotoxin (0.2μM). NT-induced contractile responses were abolished in Ca<SUP>2⁢</SUP>-free solution and reduced greatly to near abolition by 10μM of verapamil or 0.2 mM of CdCl<SUB>2</SUB>. Verapamil attenuated the effects of NT on frequency and amplitude of the slow waves. Taken together, these results indicate that NT enhances contractility in guinea-pig gastric antral circular muscle and Ca<SUP>2⁢</SUP> influx through the voltage-operated Ca<SUP>2⁢</SUP> channel appears to play an important role in the NT-induced contractile mechanism.

Transient Receptor Potential C4/5 Like Channel Is Involved in Stretch-Induced Spontaneous Uterine Contraction of Pregnant Rat

정승수,김영환,정지현,안덕선 대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.6

Spontaneous myometrial contraction (SMC) in pregnant uterus is greatly related with gestationalage and growing in frequency and amplitude toward the end of gestation to initiate labor. But, anaccurate mechanism has not been elucidated. In human and rat uterus, all TRPCs except TRPC2 areexpressed in pregnant myometrium and among them, TRPC4 are predominant throughout gestation,suggesting a possible role in regulation of SMC. Therefore, we investigated whether the TRP channelmay be involved SMC evoked by mechanical stretch in pregnant myometrial strips of rat usingisometric tension measurement and patch-clamp technique. In the present results, hypoosmotic cellswelling activated a potent outward rectifying current in G protein-dependent manner in rat pregnantmyocyte. The current was significantly potentiated by 1μM lanthanides (a potent TRPC4/5 stimulator)and suppressed by 10μM 2-APB (TRPC4-7 inhibitor). In addition, in isometric tension experiment,SMC which was evoked by passive stretch was greatly potentiated by lanthanide (1μM) andsuppressed by 2-APB (10μM), suggesting a possible involvement of TRPC4/5 channel in regulationof SMC in pregnant myometrium. These results provide a possible cellular mechanism for regulationof SMC during pregnancy and provide basic information for developing a new agent for treatmentof premature labor.

Transient Receptor Potential C4/5 Like Channel Is Involved in Stretch-Induced Spontaneous Uterine Contraction of Pregnant Rat

Chung, Seungsoo,Kim, Young-Hwan,Joeng, Ji-Hyun,Ahn, Duck-Sun The Korean Society of Pharmacology 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.6

Spontaneous myometrial contraction (SMC) in pregnant uterus is greatly related with gestational age and growing in frequency and amplitude toward the end of gestation to initiate labor. But, an accurate mechanism has not been elucidated. In human and rat uterus, all TRPCs except TRPC2 are expressed in pregnant myometrium and among them, TRPC4 are predominant throughout gestation, suggesting a possible role in regulation of SMC. Therefore, we investigated whether the TRP channel may be involved SMC evoked by mechanical stretch in pregnant myometrial strips of rat using isometric tension measurement and patch-clamp technique. In the present results, hypoosmotic cell swelling activated a potent outward rectifying current in G protein-dependent manner in rat pregnant myocyte. The current was significantly potentiated by $1{\mu}M$ lanthanides (a potent TRPC4/5 stimulator) and suppressed by $10{\mu}M$ 2-APB (TRPC4-7 inhibitor). In addition, in isometric tension experiment, SMC which was evoked by passive stretch was greatly potentiated by lanthanide ($1{\mu}M$) and suppressed by 2-APB ($10{\mu}M$), suggesting a possible involvement of TRPC4/5 channel in regulation of SMC in pregnant myometrium. These results provide a possible cellular mechanism for regulation of SMC during pregnancy and provide basic information for developing a new agent for treatment of premature labor.