title: Three-dimensional (87)Rb NMR imaging and spectroscopy of K(+) fluxes in normal and postischemic pig hearts.
abstract: K(+) uptake rates were measured in the anterior (An) and posterior (Pos) LV walls of pig hearts before and after regional ischemia and reperfusion using Rb(+) as a K(+) congener and 3D (87)Rb NMR imaging and spectroscopy as detection methods. The hearts were perfused by the Langendorff method with Krebs-Henseleit (KH) buffer and loaded with Rb(+) (4.7 mM, Rb-KH) after 120-min ischemia and 60-min reperfusion. A second protocol involved Rb(+) loading prior to ischemia. Ischemia was produced by occlusion of the left anterior descending artery, which after 110 min of reperfusion resulted in infarction in the An wall (24 +/- 6% of the LV mass) determined by triphenyltetrazolium chloride staining. At the end of reperfusion pressure-rate product and oxygen consumption rate decreased to 58 +/- 10 and 74 +/- 4% of their preischemic values, respectively. Phosphocreatine, ATP, and intracellular pH (pHi), measured by (31)P NMR spectroscopy in the infarcted area, decreased to 59 +/- 17, 32 +/- 6%, and 6.7 +/- 0.36 (from 7.05 +/- 0.13), respectively. Serial (87)Rb images were acquired according to both protocols. Rate constants (k x 10(3), min(-1)), relative amount of intracellular Rb(+) (A, %) and relative fluxes (F = kA, %/min) for the An and Pos walls were determined from the images. Before ischemia, F and k were comparable in the Pos and An walls. Ischemia + reperfusion decreased F in the An wall (from 4.4 +/- 0.3 to 1.4 +/- 0.85) due to a decrease in A (20 vs. 73) and increased F in Pos wall (from 3.2 +/- 0.6 to 6.6 +/- 0.23) due to an increase in k (from 42 +/- 3 to 93 +/- 6). The intensities of the Rb images correlated with the Rb(+) content measured in tissue samples. Magn Reson Med 44:83-91, 2000. Published 2000 Wiley-Liss, Inc.
authors.affiliation: Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, MB, Canada. Kupriyanov@IBD.NRC.CA
authors.forename: V V
authors.initials: VV
authors.lastname: Kupriyanov
authors.forename: B
authors.initials: B
authors.lastname: Xiang
authors.forename: J
authors.initials: J
authors.lastname: Sun
authors.forename: G
authors.initials: G
authors.lastname: Dai
authors.forename: O
authors.initials: O
authors.lastname: Jilkina
authors.forename: V
authors.initials: V
authors.lastname: Dao
authors.forename: R
authors.initials: R
authors.lastname: Deslauriers
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D017202:Myocardial Ischemia / Q000378:metabolism* / Q000473:pathology*; D009206:Myocardium / Q000378:metabolism*; D009336:Necrosis; D011188:Potassium / Q000378:metabolism*; D011194:Potassium Isotopes; D012414:Rubidium Radioisotopes / Q000493:pharmacokinetics; D013552:Swine; D014022:Tissue Survival / Q000502:physiology
chemical_list: D011194:Potassium Isotopes; D012414:Rubidium Radioisotopes; D011188:Potassium