3-DIMENSIONAL RB-87 IMAGING OF ISOLATED PIG HEARTS - EFFECTS OF REGIONAL ISCHEMIA

The aim of this work was to investigate whether 1) nb uptake is reduce d in ischemic myocardium, and 2) Rb-87 three-dimensional (3D) imaging can detect the ischemic area. Hearts of domestic pigs (n = 8, 20-30 kg ) were perfused retrogradely with Krebs-Henseleit buffer in a 7-T, 40- cm horizontal bore magnet interfaced with Bruker MSLX spectrometer. Co ntrol (C) and ischemic (I) (45 min ligation of the left anterior desce nding coronary artery (LAD)) hearts were loaded with Rb+ by perfusion with a Rb+-containing solution (2-4.7 mM, 30-100% of K+ substitution) for 35 min and Rb-87 (C) or P-31 (ischemic area in I) spectra were acq uired. After mechanical arrest with 0.6-0.9 mM lidocaine, Rb-87 images (7 min each, 1 cm(3) resolution) were acquired (30-40 min) in the pre sence of Rb+-containing perfusate, Subsequently, the hearts were stain ed with Evans blue (EB) and samples taken for measurements of Rb+ cont ent. In the Group C, distribution of Rb+ in the left ventricle and the intensities of the 3D Rb-87 images were uniform. In the ischemic area (Group I), verified by the lack of EB staining and changes in P-31 sp ectra, the images showed a reduced intensity, which corresponded to de creased Rb+ content (33 +/- 11% of the normal). Thus, Rb-87 imaging re veals damaged cells detecting reduced Rb+ content in the ischemic area .