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Three‐dimensional 87 Rb NMR imaging and spectroscopy of K + fluxes in normal and postischemic pig hearts
Author(s) -
Kupriyanov V.V.,
Xiang B.,
Sun J.,
Dai G.,
Jilkina O.,
Dao V.,
Deslauriers R.
Publication year - 2000
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/1522-2594(200007)44:1<83::aid-mrm13>3.0.co;2-r
Subject(s) - phosphocreatine , ischemia , chemistry , intracellular ph , nuclear magnetic resonance spectroscopy , intracellular , oxygen , nuclear magnetic resonance , cardiology , medicine , energy metabolism , biochemistry , stereochemistry , physics , organic chemistry
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 × 10 3 , min −1 ), relative amount of intracellular Rb + (A, %) and relative fluxes (F = k A, %/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.