Dexamethasone effects on (/sup 125/I)albumin distribution in experimental RG-2 gliomas and adjacent brain

Journal Article · Tue Dec 01 04:00:00 EST 1987 · J. Cereb. Blood Flow Metab.; (United States)

DOI:https://doi.org/10.1038/jcbfm.1987.123· OSTI ID:5515720

Nakagawa, H; Groothuis, D R; Owens, E S; Fenstermacher, J D; Patlak, C S; Blasberg, R G

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

• Research Organization: National Institutes of Health, Bethesda, MD
• OSTI ID: 5515720
• Journal Information: J. Cereb. Blood Flow Metab.; (United States), Journal Name: J. Cereb. Blood Flow Metab.; (United States) Vol. 7:6; ISSN JCBMD
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ALBUMINS
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL MODELS
BLOOD VESSELS
BODY
BRAIN
CAPILLARIES
CARDIOVASCULAR SYSTEM
CENTRAL NERVOUS SYSTEM
CORTICOSTEROIDS
DAYS LIVING RADIOISOTOPES
DEXAMETHASONE
DISEASES
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
EXPERIMENTAL NEOPLASMS
GLIOMAS
GLUCOCORTICOIDS
HORMONES
HYDROXY COMPOUNDS
INJECTION
INTAKE
INTERMEDIATE MASS NUCLEI
INTRAVENOUS INJECTION
IODINE 125
IODINE ISOTOPES
ISOTOPES
KETONES
MAMMALS
NEOPLASMS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PREGNANES
PROTEINS
RADIOISOTOPES
RATS
RODENTS
STEROID HORMONES
STEROIDS
TISSUE DISTRIBUTION
TRANSPLANTS
VERTEBRATES