Intracellular localization of (99m)Tc-d,l-HMPAO in rat blood.
OBJECTIVE
The objective of this study was to investigate the intracellular localization of technetium 99m-hexamethylpropylene amine oxime ((99m)Tc-d,l-HMPAO) in rat red blood cells (RBCs) and plasma.


METHODS
Sprague-Dawley rats (n = 36) were injected with 129.5 MBq (99m)Tc-d,l-HMPAO. Using a heparinized syringe, 2-ml blood samples were withdrawn from the rats 10, 20, 30, 40, 50 and 60 min after (99m)Tc-d,l-HMPAO injection. Blood was centrifuged for 10 min at 2,240 rpm to separate RBCs from plasma. A chloroform/methanol/distilled water mixture was added to the RBCs and plasma in separate tubes to extract (99m)Tc-d,l- HMPAO into aqueous (Aq) and lipid (Lp) phases. The (99m)Tc-d,l-HMPAO activities in Aq and Lp phases were measured separately using a dose calibrator. The data were analyzed using Student's t test and a one-way ANOVA.


RESULTS
More than 70% of the injected dose of (99m)Tc-d,l-HMPAO was retained in the RBCs for up to 60 min, compared to less than 20% in plasma. The uptakes in the Aq for plasma were 88.77 +/- 1.04, 94.23 +/- 2.42, 90.15 +/- 1.88, 98.59 +/- 0.89, 96.42 +/- 1.50 and 97.59 +/- 1.92% at 10, 20, 30, 40, 50 and 60 min after injection, respectively. The corresponding uptakes in the Lp phases were: 11.23 +/- 0.04, 5.77 +/- 0.07, 9.85 +/- 0.06, 1.41 +/- 0.08, 3.58 +/- 0.04 and 2.41 +/- 0.06, respectively. Similar values (% +/- SE) and trends were obtained in the Aq and Lp phases for RBCs. A highly significant difference between the Aq and Lp phases at each time point studied was observed (p < 0.0001). There was no statistically significant difference between the time points in the Aq phase, but there was a significant difference (p < 0.001) between time points in the Lp phase.


CONCLUSIONS
This study demonstrated that most of the intracellular localization of (99m)Tc-d,l-HMPAO was in the Aq phase compared to Lp phase in both RBCs and plasma up to 60 min.
Department of Nuclear Medicine, Faculty of Medicine, Kuwait University, 13110 Safat Kuwait. fatimas@hsc.edu.kw
Fatma J
FJ
Al-Saeedi
Sati
S
Gopinath
D000818:Animals; D004912:Erythrocytes / Q000737:chemistry*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D010091:Oximes / Q000493:pharmacokinetics*; D010949:Plasma / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015609:Organotechnetium Compounds; D010091:Oximes; C068296:hexamethylpropyleneamine oxime