Correlation of myocardial necrosis with kinetics of 111In-labeled myosin-specific antibody in isolated rabbit septum.
Radiolabeled monoclonal antibody fragments to myosin, specifically 111In-labeled antimyosin, have been shown to be effective for imaging areas of myocardial infarct. To determine if 111In-labeled antimyosin can be used to assess the extent of necrosis, we compared the tissue retention fraction of 111In-labeled antimyosin with the amount of creatine kinase (CK) released from the isolated, perfused, interventricular rabbit septum after an intervention to induce tissue necrosis. 111In-labeled antimyosin was injected and tissue radioactivity was monitored for a 60-min period under control conditions. Effluent samples were also collected during this period and assayed for CK content. After a period of Ca2+ depletion followed by Ca2+ repletion, 111In-labeled antimyosin was again injected, and washout and CK data were collected. Comparison of the changes in 111In-labeled antimyosin retention fraction from control to intervention with the corresponding increase in CK released during intervention resulted in a correlation coefficient of 0.83. To corroborate the findings of the Ca2+ depletion followed by repletion experiments, further experiments were conducted in which zero-flow ischemia followed by reperfusion was used as a means of introducing necrosis in the septum. The resulting correlation coefficient between CK release and 111In-labeled antimyosin retention fraction was 0.82. The results of these experiments indicate that 111In-labeled antimyosin can be used to quantitatively estimate the extent of necrosis in the rabbit septum, as determined by CK release, and endorse the potential use of tracer kinetics in humans for quantitation of myocardial necrosis in vivo.
Williams
B A
BA
Department of Radiological Sciences, University of California, Los Angeles 90024.
Huang
S C
SC
Krivokapich
J
J
Buxton
D B
DB
Schelbert
H R
HR
D000818:Animals; D000906:Antibodies / Q000276:immunology*; D002118:Calcium / Q000493:pharmacokinetics; D003402:Creatine Kinase / Q000378:metabolism; D006346:Heart Septum / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D007205:Indium Radioisotopes; D007700:Kinetics; D008297:Male; D009200:Myocardial Contraction; D009218:Myosins / Q000276:immunology / Q000378:metabolism*; D009336:Necrosis; D011817:Rabbits
D000906:Antibodies; D007205:Indium Radioisotopes; D003402:Creatine Kinase; D009218:Myosins; D002118:Calcium