title: Potassium transport in Langendorff-perfused mouse hearts assessed by 87Rb NMR spectroscopy.
abstract: We studied the fluxes of a potassium congener (Rb(+)) in mouse hearts by (87)Rb MRS at 8.4T. The hearts were loaded with Rb(+) by perfusion with Krebs-Henseleit buffer, in which 50% of K(+) was substituted with Rb(+). We initiated Rb(+) efflux by changing the perfusion medium to Rb(+)-free buffer. Spectra were acquired every 1.85 min, and the kinetics of Rb(+) transport were analyzed by means of monoexponential fits. The rate constants of Rb(+) uptake and efflux were 0.0680 +/- 0.0028 and 0.0510 +/- 0.0051 min(-1), respectively (approximately 30% faster than in the rat heart). The ATP-sensitive potassium channel opener, P-1075 (5 microM), and mitochondrial uncoupler, 2,4-dintrophenol (50 microM), activated Rb(+) efflux from mouse hearts by approximately 35%. The mechanisms responsible for the differences in Rb(+) uptake and efflux under baseline conditions and stimulation, in comparison with rat hearts, are discussed. These data provide a background for studies of cardiac potassium transport in transgenic mouse strains.
authors.affiliation: Institute for Biodiagnostics, National Research Council, Winnipeg, Canada.
authors.forename: Olga
authors.initials: O
authors.lastname: Jilkina
authors.forename: Bo
authors.initials: B
authors.lastname: Xiang
authors.forename: Bozena
authors.initials: B
authors.lastname: Kuzio
authors.forename: John
authors.initials: J
authors.lastname: Rendell
authors.forename: Valery V
authors.initials: VV
authors.lastname: Kupriyanov
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003326:Coronary Circulation; D017136:Ion Transport; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012414:Rubidium Radioisotopes; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D012414:Rubidium Radioisotopes; D010725:Phosphocreatine; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium