Dexamethasone effects on [125I]albumin distribution in experimental RG-2 gliomas and adjacent brain.

摘要: A total of 72 RG-2 transplanted gliomas were studied in 58 rats at three time points (1, 30, 240 min) after intravenous injection (/sup 125/I)radioiodinated serum albumin ((/sup 125/I)RISA). The animals divided into two groups: a control group that received no treatment and second was treated with five doses 1.5 mg/kg dexamethasone over 2.5 days. Local tissue concentrations 125/I)RISA measured quantitative autoradiography based on morphological features the tumors used to calculate distribution space. Two models analyze data. compartment model yielded estimates local blood-to-tissue influx constants (K1), lower limit extracellular volumes (Ve), plasma vascular (Vp) different tumor regions. Treatment consistently reduced RISA space tumors; reduction Ve statistically significant almost all regions: whole (mean +/- SE) from 0.14 0.02 ml g-1 0.08 0.01 animals. K1 Vp also decreased regions (whole 2.36 0.89 0.83 0.29more » microliter min-1 slightly 0.016 0.013 0.010 0.005 treatment), but these changes not significant. comparison aqueous diffusion size molecules (RISA aminoisobutyric acid) suggests ''pores'' across capillaries are large may restrict free (estimated minimum pore diameter greater than 36 nm) area is approximately 6.2 X 10(-5) cm2 tissue.« less