SPECT using 99mTc-hexamethyl propyleneamine oxime (HMPAO) mainly reflects regional cerebral blood flow, however metabolic abnormalities also affect the retention of 99mTc-HMPAO. Methods: To rule out any flow factor, a test-tube model was used to evaluate the effects of metabolic alterations both on intracellular trapping of 99mTc-HMPAO and on extracellular glutamate and lactate dehydrogenase (LDH) outflow from rat brain slices. Results: Under control conditions, slices took up 7.0% ± 1.4% of 99mTc- HMPAO contained in the medium, whereas prelabeled slices released 10.8% ± 2.6% of their radioactive content; glutamate and LDH outflow were 49.1 ± 21.6 pmol/mg protein/min and 4.8 ± 0.9 U/L/mg protein/min, respectively. The control medium was altered by adding a metabolic poison (5 mmol/L azide), removing glucose and replacing O2 with N2 to mimic ischemia (in vitro ischemia) and replacing Krebs solution with hypotonic medium to evoke cell lysis. Both azide and in vitro ischemia induced a sig...
New Insights on Flow-Independent Mechanisms of 99mTc-HMPAO Retention in Nervous Tissue: In Vitro Study
CALO', Girolamo;UCCELLI, Licia;CITTANTI, Corrado;GIGANTI, Melchiore;PIFFANELLI, Adriano
1999
Abstract
SPECT using 99mTc-hexamethyl propyleneamine oxime (HMPAO) mainly reflects regional cerebral blood flow, however metabolic abnormalities also affect the retention of 99mTc-HMPAO. Methods: To rule out any flow factor, a test-tube model was used to evaluate the effects of metabolic alterations both on intracellular trapping of 99mTc-HMPAO and on extracellular glutamate and lactate dehydrogenase (LDH) outflow from rat brain slices. Results: Under control conditions, slices took up 7.0% ± 1.4% of 99mTc- HMPAO contained in the medium, whereas prelabeled slices released 10.8% ± 2.6% of their radioactive content; glutamate and LDH outflow were 49.1 ± 21.6 pmol/mg protein/min and 4.8 ± 0.9 U/L/mg protein/min, respectively. The control medium was altered by adding a metabolic poison (5 mmol/L azide), removing glucose and replacing O2 with N2 to mimic ischemia (in vitro ischemia) and replacing Krebs solution with hypotonic medium to evoke cell lysis. Both azide and in vitro ischemia induced a sig...I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
