title: Phosphodiesterase inhibitor KMUP-3 displays cardioprotection via protein kinase G and increases cardiac output via G-protein-coupled receptor agonist activity and Ca(2+) sensitization.
abstract: KMUP-3 (7-{2-[4-(4-nitrobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) displays cardioprotection and increases cardiac output, and is suggested to increase cardiac performance and improve myocardial infarction. To determine whether KMUP-3 improves outcomes in hypoperfused myocardium by inducing Ca(2+) sensitization to oppose protein kinase (PK)G-mediated Ca(2+) blockade, we measured left ventricular systolic blood pressure, maximal rates of pressure development, mean arterial pressure and heart rate in rats, and measured contractility and expression of PKs/RhoA/Rho kinase (ROCK)II in beating guinea pig left atria. Hemodynamic changes induced by KMUP-3 (0.5-3.0 mg/kg, intravenously) were inhibited by Y27632 [(R)-(+)-trans-4-1-aminoethyl)-N-(4-Pyridyl) cyclohexane carboxamide] and ketanserin (1 mg/kg, intravenously). In electrically stimulated left guinea pig atria, positive inotropy induced by KMUP-3 (0.1-100μM) was inhibited by the endothelial NO synthase (eNOS) inhibitors N-nitro-l-arginine methyl ester (L-NAME) and 7-nitroindazole, cyclic AMP antagonist SQ22536 [9-(terahydro-2-furanyl)-9H-purin-6-amine], soluble guanylyl cyclase (sGC) antagonist ODQ (1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one), RhoA inhibitor C3 exoenzyme, β-blocker propranolol, 5-hydroxytryptamine 2A antagonist ketanserin, ROCK inhibitor Y27632 and KMUP-1 (7-{2-[4-(2-chlorobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) at 10μM. Western blotting assays indicated that KMUP-3 (0.1-10μM) increased PKA, RhoA/ROCKII, and PKC translocation and CIP-17 (an endogenous 17-kDa inhibitory protein) activation. In spontaneous right atria, KMUP-3 induced negative chronotropy that was blunted by 7-nitroindazole and atropine. In neonatal myocytes, L-NAME inhibited KMUP-3-induced eNOS phosphorylation and RhoA/ROCK activation. In H9c2 cells, Y-27632 (50μM) and PKG antagonist KT5823 [2,3,9,10,11,12-hexahydro-10R- methoxy-2,9-dimethyl-1-oxo-9S,12R-epoxy-1H-diindolo(1,2,3-fg:3',2',1'-kl) pyrrolo(3,4-i)(1,6)benzodiazocine-10-carboxylic acid, methyl ester] (3μM) reversed KMUP-3 (1-100μM)-induced Ca(2+)-entry blockade. GPCR agonist activity of KMUP-3 appeared opposed to KMUP-1, and increased cardiac output via Ca(2+) sensitization, and displayed cardioprotection via cyclic GMP/PKG-mediated myocardial preconditioning in animal studies.
authors.affiliation: Department of Internal Medicine, Yuan's General Hospital, Kaohsiung, Taiwan.
authors.forename: Chung-Pin
authors.initials: CP
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jwu-Lai
authors.initials: JL
authors.lastname: Yeh
authors.affiliation: Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Liou
authors.affiliation: Department of Pharmacology, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Bin-Nan
authors.initials: BN
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Medicine and Education, Pingtung Christian Hospital, Pingtung, Taiwan. Electronic address: ingjun@kmu.edu.tw.
authors.forename: Ing-Jun
authors.initials: IJ
authors.lastname: Chen
mesh_terms: D000818:Animals; D001794:Blood Pressure; D020013:Calcium Signaling; D002227:Carbazoles / Q000494:pharmacology; D002302:Cardiac Output / Q000187:drug effects*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002460:Cell Line; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria / Q000503:physiopathology; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D021381:Protein Transport; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D017725:Ventricular Pressure; D014970:Xanthines / Q000494:pharmacology*
chemical_list: C508169:7-(2-(4-(4-nitrobenzene)piperazinyl)ethyl)-1,3-dimethylxanthine; D002227:Carbazoles; D002316:Cardiotonic Agents; D010726:Phosphodiesterase Inhibitors; D010880:Piperidines; D043562:Receptors, G-Protein-Coupled; D014970:Xanthines; C073601:KT 5823; D017869:Cyclic GMP-Dependent Protein Kinases
keywords: Ca(2+) entry; Cardiac output; Cardioprotection; G-protein-coupled receptor; PKG