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- 저자 : Chidipi, B. (검색결과 5 건)
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Chidipi, B.,Son, M.J.,Kim, J.C.,Lee, J.H.,Toan, T.Q.,Cuong, N.M.,Lee, B.H.,Woo, S.H. North-Holland ; Elsevier Science Ltd 2016 european journal of pharmacology Vol.784 No.-
<P>We previously reported that murrayafoline-A (1-methoxy-3-methyl-9H-carbazole, Mu-A) increases the contractility of ventricular myocytes, in part, via enhancing Ca2+ influx through L-type Ca2+ channels, and that it increases the Ca2+ transients by activation of protein kinase C (PKC). In the present study, we further examined the cellular mechanisms for the enhancement of contractility and L-type Ca2+ current (I-ca,I-L) by Mu-A. Cell shortening and I-Ca,I-L were measured in rat ventricular myocytes using a video edge detection method and perforated patch-clamp technique, respectively. We found that the positive inotropic effect of Mu-A was not affected by pre-exposure to the beta-adrenoceptor antagonist propranolol, the protein kinase A (PIGS) inhibitors KT5720 or H-89, or the phospholipase C inhibitor U73122. Interestingly, the Mu-A-mediated increases in cell shortening and in the rate of contraction were completely suppressed by pre-treatment with the PKC inhibitor GF109203X. The stimulatory effect of Mu-A on I-Ca,I-L was not altered by inhibition of PKA (KT5720), G-protein coupled receptors (suramin), or alpha(1)-adrenoceptor (prazosin). However, pre-exposure to the PKC inhibitor, GF109203X or chelerythrine, abolished the Mu-A-induced increase in I-Ca,I-L. Pre-exposure to the Ca2+-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93 slightly reduced the stimulatory effects on contraction and I-Ca,I-L by Mu-A. Phosphorylation of PKC was enhanced by Mu-A in ventricular myocytes. These data suggest that Mu-A increases contraction and I-Ca,I-L via PKC in rat ventricular myocytes, and that the PKC-mediated responses in the presence of Mu-A may be partly mediated by CaMKII. (C) 2016 Elsevier B.V. All rights reserved.</P>
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전단 자극 시 심방근세포 간극접합 채널 활성화에 의한 P2 퓨린수용체-매개 비선택성 양이온 전류의 발생
손민정,김준철,브지바부 치디피,왕준,김경희,우선희 충남대학교 약학대학 의약품개발연구소 2016 藥學論文集 Vol.31 No.-
Atrial myocytes are subjected to shear stress under physiological and pathological conditions during cardiac cycle. We recently reported that gap junction hemichannels play a role in the generation of Ca2+ wave in atrial cells under shear stress. In the present study, we examined whether ionic current is generated by the activation of gap junction hemichannels in rat atrial myocytes under shear stress using whole-cell patch clamp method combined with a pressurized microflow system. Shear stress of ~16 dyne/cm2 (1-s long) produced a slow inward current (ISS) at –70 mV in symmetrical CsCl-rich solutions.Removal of external Ca2+ to enhance hemichannel opening increased this shear-activated current by approximately 140%. In addition, the ISS was almost completely inhibited by the hemichannel blockers carbenoxolone (50 μM) or La3+ (2 mM). We next tested whether P2 purinoceptors activated by ATP released via hemichannels contribute to ISS cells using P2-purinoceptor antagonist suramin. Pre-treatment of suramin (10 μM) suppressed ISS to ~28% of control. When the delayed rectifying K+ channels, that have slight permeability to Cs+, were blocked using 4-aminopyridine (200 μM), ISS was not altered. Our data suggest that shear stress may activate gap-junction hemichannels, resulting in ATP release with subsequent P2 purinoceptor-mediated nonselective cation current in atrial myocytes.
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Son, M.J.,Chidipi, B.,Kim, J.C.,Huong, T.T.,Tai, B.H.,Kim, Y.H.,Ahn, J.R.,Cuong, N.M.,Woo, S.H. North-Holland ; Elsevier Science Ltd 2014 european journal of pharmacology Vol.740 No.-
We examined the effects of murrayafoline-A (1-methoxy-3-methylcarbazole, Mu-A), which is isolated from the dried roots of Glycosmis stenocarpa, on cell shortenings and L-type Ca<SUP>2+</SUP> currents (I<SUB>Ca,L</SUB>) in rat ventricular myocytes. Cell shortenings and I<SUB>Ca,L</SUB> were measured using the video edge detection method and patch-clamp techniques, respectively. Mu-A transiently increased cell shortenings in a concentration-dependent manner with an EC<SUB>50</SUB> of ~20μM. The maximal effect of Mu-A, approximately 175% of the control, was observed at ≥100μM. The positive inotropic effect of Mu-A (25μM) reached a maximum after ~2-min exposures, and then decayed after a ~1-min steady-state. During the Mu-A-induced positive inotropy, the rate of contraction was accelerated, whereas the rate of relaxation was not significantly altered. To understand the possible mechanism for the Mu-A-induced positive inotropy, the I<SUB>Ca,L</SUB> was assessed. Mu-A transiently enhanced the I<SUB>Ca,L</SUB>. Concentration-dependence of the increase in I<SUB>Ca,L</SUB> by Mu-A was similar to that of positive inotropic effect of Mu-A. The maximal effect of Mu-A (25μM) on I<SUB>Ca,L</SUB> was observed at 2-3min after the application of Mu-A. A partial inhibition of I<SUB>Ca,L</SUB> using verapamil (1μM) induced a right shift of concentration-response curve of the positive inotropic effect of Mu-A and significantly attenuated the effect. These results suggest that Mu-A may transiently enhance contractility, at least in part, by increasing the Ca<SUP>2+</SUP> influx through the L-type Ca<SUP>2+</SUP> channels in rat ventricular myocytes.
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Subedi, Krishna P.,Son, Min-Jeong,Chidipi, Bojjibabu,Kim, Seong-Woo,Wang, Jun,Kim, Kyeong-Hee,Woo, Sun-Hee,Kim, Joon-Chul S. Karger AG 2017 CELLULAR PHYSIOLOGY AND BIOCHEMISTRY Vol.41 No.1
<P><B><I>Background/Aims:</I></B> Endothelin-1 (ET-1) and the α<Sub>1</Sub>-adrenoceptor agonist phenylephrine (PE) activate cAMP response element binding protein (CREB), a transcription factor implicated in cardiac hypertrophy. The signaling pathway involved in CREB activation by these hypertrophic stimuli is poorly understood. We examined signaling pathways for ET-1- or PE-induced cardiac CREB activation. <B><I>Methods:</I></B> Western blotting was performed with pharmacological and genetic interventions in rat ventricular myocytes. <B><I>Results:</I></B> ET-1 and PE increased CREB phosphorylation, which was inhibited by blockade of phospholipase C, the extracellular-signal-regulated kinase 1/2 (ERK1/2) pathway, protein kinase C (PKC) or Ca<SUP>2+</SUP>-calmodulin-dependent protein kinase II (CaMKII). Intracellular Ca<SUP>2+</SUP> buffering decreased ET-1- and PE-induced CREB phosphorylation by ≥80%. Sarcoplasmic reticulum Ca<SUP>2+</SUP> pump inhibitor, inositol 1,4,5-trisphosphate receptor (IP<Sub>3</Sub>R) blockers, or type 2 IP<Sub>3</Sub>R (IP<Sub>3</Sub>R2) knock-out abolished ET-1- or PE-induced CREB phosphorylation. ET-1 and PE increased phosphorylation of CaMKII and ERK1/2, which was eliminated by IP<Sub>3</Sub>R blockade/knock-out or PKC inhibition. Activation of CaMKII, but not ERK1/2, by these agonists was sensitive to Ca<SUP>2+</SUP> buffering or to Gö6976, the inhibitor of Ca<SUP>2+</SUP>-dependent PKC and protein kinase D (PKD). <B><I>Conclusion:</I></B> CREB phosphorylation by ET-1 and PE may be mainly mediated by IP<Sub>3</Sub>R2/Ca<SUP>2+</SUP>-PKC-PKD-CaMKII signaling with a minor contribution by ERK1/2, linked to IP<Sub>3</Sub>R2 and Ca<SUP>2+</SUP>-independent PKC, in ventricular myocytes.</P>
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