Dexmedetomidine-Induced Contraction Involves

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International Journal of

Molecular Sciences Article

Dexmedetomidine-Induced Contraction Involves CPI-17 Phosphorylation in Isolated Rat Aortas Seong-Ho Ok 1,† , Seong-Chun Kwon 2,† , Jiseok Baik 3 , Jeong-Min Hong 3 , Jiah Oh 4 , Jeong Yeol Han 5 and Ju-Tae Sohn 1,6, * 1 2 3

4 5 6

* †

Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si 52727, Korea; [email protected] Department of Physiology, Institute for Clinical and Translational Research, Catholic Kwandong University College of Medicine, Gangneung 25601, Korea; [email protected] Department of Anesthesiology and Pain Medicine, Pusan National University Hospital, Biomed Research Institute, Pusan National University School of Medicine, Busan 49241, Korea; [email protected] (J.B.); [email protected] (J.-M.H.) Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju-si 52727, Korea; [email protected] Department of Anesthesiology and Pain Medicine, Gyeongsang National University Changwon Hospital, Changwon 51472, Korea; [email protected] Institute of Health Sciences, Gyeongsang National University, Jinju 52727, Korea Correspondence: [email protected]; Tel.: +82-55-750-8586; Fax: +82-55-750-8142 These authors contributed equally to this work.

Academic Editor: ChulHee Kang Received: 19 August 2016; Accepted: 26 September 2016; Published: 30 September 2016

Abstract: Dexmedetomidine, a highly selective α-2 adrenoceptor agonist, produces vasoconstriction, which leads to transiently increased blood pressure. The goal of this study was to investigate specific protein kinases and the associated cellular signal pathways responsible for the increased calcium sensitization induced by dexmedetomidine in isolated rat aortas, with a particular focus on phosphorylation-dependent inhibitory protein of myosin phosphatase (CPI-17). The effect of Y-27632 and chelerythrine on the dexmedetomidine-induced intracellular calcium concentration ([Ca2+ ]i ) and tension were assessed using fura-2-loaded aortic strips. The effects of rauwolscine, Y-27632, chelerythrine, and ML-7 hydrochloride on the dexmedetomidine-induced phosphorylation of CPI-17 or of the 20-kDa regulatory light chain of myosin (MLC20 ) were investigated in rat aortic vascular smooth muscle cells. The effects of rauwolscine, Y-27632, and chelerythrine on the membrane translocation of Rho-kinase and protein kinase C (PKC) phosphorylation induced by dexmedetomidine were assessed. Y-27632 and chelerythrine each reduced the slopes of the [Ca2+ ]i -tension curves of dexmedetomidine-induced contraction, and Y-27632 more strongly reduced these slopes than did chelerythrine. Rauwolscine, Y-27632, chelerythrine, and ML-7 hydrochloride attenuated the dexmedetomidine-induced phosphorylation of CPI-17 and MLC20 . Taken together, these results suggest that dexmedetomidine-induced contraction involves calcium sensitization, which appears to be mediated by CPI-17 phosphorylation via Rho-kinase or PKC. dexmedetomidine; Rho-kinase; protein kinase C; calcium Keywords: phosphorylation-dependent inhibitory protein of myosin phosphatase; aorta

sensitization;

1. Introduction As a highly selective α-2 adrenoceptor agonist, dexmedetomidine induces sedation, reduces the opioid analgesic requirement, and attenuates the hemodynamic response to anesthesia and surgery [1,2]. Because of these characteristics, dexmedetomidine is widely used during the Int. J. Mol. Sci. 2016, 17, 1663; doi:10.3390/ijms17101663

www.mdpi.com/journal/ijms

Int. Int.J.J.Mol. Mol.Sci. Sci.2016, 2016,17, 17,1663 1663

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surgery [1,2]. Because of these characteristics, dexmedetomidine is widely used during the perioperative period of dexmedetomidine produces a biphasic blood perioperative period [1,2]. [1,2].Intravenous Intravenousadministration administration of dexmedetomidine produces a biphasic pressure response, which consists of transient hypertension followed by decreased blood pressure [3]. blood pressure response, which consists of transient hypertension followed by decreased blood This initial hypertension is due to α-2 adrenoceptor stimulation of vascular smooth pressure [3]. transient This initial transient hypertension is due to α-2 adrenoceptor stimulation of vascular muscle, muscle, whereas whereas the observed decrease indecrease blood pressure is associated a centralwith sympatholytic smooth the observed in blood pressure iswith associated a central effect evoked by dexmedetomidine [4–8]. In particular, dose or ahigh of sympatholytic effect evoked by dexmedetomidine [4–8]. aInhigh particular, highconcentration dose or high dexmedetomidine produces severe hypertension, which appears to be which associated with to α-2be adrenoceptor concentration of dexmedetomidine produces severe hypertension, appears associated stimulation of vascularstimulation smooth muscle [9–12]. smooth muscle [9–12]. with α-2 adrenoceptor of vascular Contraction of of vascular vascular smooth smooth muscle muscle isis regulated regulated by by both both calcium-dependent calcium-dependent and and Contraction calcium-sensitization mechanisms mechanisms [13]. [13]. InInthe thecalcium-sensitization calcium-sensitizationmechanism, mechanism,the theslope slope of of the the calcium-sensitization intracellularcalcium calcium concentration concentration ([Ca ([Ca2+2+ ]i )-tensioncurve curveinduced inducedby byan anagonist agonistor ordrug drugisis higher higher intracellular ]i)-tension thanthat that induced induced by by the the depolarization depolarization evoked evoked by by high high KCl KCl concentrations concentrations [13,14]. [13,14]. The The underlying underlying than mechanism responsible is is associated with the the inhibition of myosin light chain mechanism responsible for forcalcium calciumsensitization sensitization associated with inhibition of myosin light phosphatase (MLCP), leading to increased phosphorylation of the 20-kDa regulatory light chain of chain phosphatase (MLCP), leading to increased phosphorylation of the 20-kDa regulatory light myosin and subsequently enhanced contraction [13,14]. The inhibition of MLCPofinMLCP vascular chain of (MLC myosin 20) and subsequently enhanced contraction [13,14]. The inhibition in 20 )(MLC smooth muscle mediated by phosphorylation of either the phosphorylation-dependent inhibitory vascular smoothismuscle is mediated by phosphorylation of either the phosphorylation-dependent protein of myosin or the(CPI-17) myosin phosphatase target subunit of MLCP either inhibitory protein phosphatase of myosin (CPI-17) phosphatase or the myosin phosphatase target via subunit Rho-kinase or protein C (PKC),orwhich leads kinase to attenuated dephosphorylation of MLCP via eitherkinase Rho-kinase protein C (PKC), which leads oftoMLC attenuated 20 [13,14]. We previously reported that the slopes [Ca2+ ]i -tension curves induced are dephosphorylation of MLC 20 [13,14]. We of previously reported that the slopesby ofdexmedetomidine [Ca2+]i-tension curves higher than induced by high in isolated aortas, suggesting thatKCl dexmedetomidine-induced induced by those dexmedetomidine areKCl higher than rat those induced by high in isolated rat aortas, contractionthat produces a relatively greater increase in calcium However, suggesting dexmedetomidine-induced contraction producessensitization a relatively [15]. greater increase the in specific protein kinases andHowever, associatedthe cellular pathways responsible forcellular increased calcium calcium sensitization [15]. specific protein primarily kinases and associated pathways sensitization in response dexmedetomidine remain unknown. Therefore, the goal of this remain in vitro primarily responsible for to increased calcium sensitization in response to dexmedetomidine study wasTherefore, to investigate the specific protein kinasewas andtoassociated signaling pathways that unknown. the goal of this in vitro study investigatecellular the specific protein kinase and contribute cellular to the increased sensitization induced a particular focus associated signalingcalcium pathways that contribute to by thedexmedetomidine, increased calcium with sensitization induced ondexmedetomidine, CPI-17 phosphorylation. by with a particular focus on CPI-17 phosphorylation. 2.Results Results 2. −6 M) induced vasoconstriction (p < 0.001 versus control; Dexmedetomidine (3 (3 ×× 10 10−8−8toto1010 −6 M) Dexmedetomidine induced vasoconstriction (p < 0.001 versus control; 2+ Figures 1A and 2A) and increased [Ca ] (p 0.01 versus versus control; control; Figures Figures 1A 1A and and 2B). 2B). Y-27632 Y-27632 2+ Figures 1A and 2A) and increased [Ca ]i i (p