Uptake of 99mTc(5+)-complexes in ischemic myocardial slices and their dissociable ability

AIM: To find how some technetium-complexes to deliver the active species,
TcO4(3-), to the target tissue from a dissociable polynuclear Tc5+ species in
preserved states in vivo.
METHODS: Effect of dissociation ability of the polynuclear Tc5+ complexes on
their accumulation in ischemic myocardium was tested. Ability of dissociation as
having an appropriate conformation to become biologically functional after
entering the blood circulation was tested using a simple dilution method by thin
layer chromatography (TLC) analysis. Various degree of ischemic myocardium slices
of rat were incubated with 1/100 diluted 99mTc(5+)-succimer, 99mTc(5+)-GH and
99mTc(5+)-PPi.
RESULTS: The TLC patterns of 99mTc(5+)-GH and 99mTc(5+)-PPi showed the presence
of a fast increasing of free Tc-species as dilution degree increased. The
relative radioactivity of peak of free pertechnetate (Rf = 0.85-1.0) with 1:500
dilution was: 99mTc(5+)-succimer 0%, 99mTc(5+)-GH 28.1% +/- 1.3%, and
99mTc(5+)-PPi 46.0% +/- 2.9% respectively. The uptake of the myocardium after
ischemia for 3 h was 99mTc(5+)-succimer 420% +/- 110% dose/g tissue, 99mTc(5+)-GH
710% +/- 180% dose/g tissue, and 99mTc(5+)-PPi 1295% +/- 390% dose/g tissue
respectively.
CONCLUSION: The dissociation and myocardial uptake showed: 99mTc(5+)-succimer <
99mTc(5+)-GH < 99mTc(5+)-PPi, the uptake by the ischemic myocardium is positively
correlated to their dissociation.