EXTERNAL ASSESSMENT OF MYOCARDIAL-METABOLISM WITH C-11 PALMITATE INVIVO

  • 1 January 1980
    • journal article
    • research article
    • Vol. 21  (4) , 342-348
Abstract
The externally detected rate of clearance of C-11 palmitate ([11C]palmitic acid) from isolated hearts varies directly with CO2 production from neutral lipids and with physiological indexes of myocardial O2 consumption. Whether myocardial metabolism could be quantified noninvasively in vivo in a fashion analogous to the isolated heart was investigated. Opened chest, male rabbits were injected with C-11 palmitate (100-200 .mu.Ci). Coincidence counts were detected externally with 2 Nal(TI) crystals, placed so their colinear field of view encompasses the heart. The monoexponential rate of clearance of tracer, obtained from the portion of the residue-detection curve reflecting metabolism of fatty acid incorporated into neutral lipids, correlated directly with induced changes in tension-time index after injections into the left atrium (r [rate] = 0.96, n [number] = 12), right atrium (r = 0.86, n = 14) and ear vein (r = 0.93, n = 14). Clearance of labeled palmitate from the vascular pool within the field of detection (determined with C-14 palmitate and red blood cells labeled with C15O-Hb) was rapid and did not significantly affect measurements of palmitate clearance from the heart itself.

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