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

Journal Article · Tue Dec 01 00:00:00 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 (NIH), Bethesda, MD (United States)
• OSTI ID: 5515720
• Journal Information: J. Cereb. Blood Flow Metab.; (United States), Vol. 7:6
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ALBUMINS
TISSUE DISTRIBUTION
DEXAMETHASONE
BIOLOGICAL EFFECTS
GLIOMAS
TRANSPLANTS
AUTORADIOGRAPHY
BIOLOGICAL MODELS
BRAIN
CAPILLARIES
EXPERIMENTAL NEOPLASMS
INTRAVENOUS INJECTION
IODINE 125
RATS
ADRENAL HORMONES
ANIMALS
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CENTRAL NERVOUS SYSTEM
CORTICOSTEROIDS
DAYS LIVING RADIOISOTOPES
DISEASES
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
GLUCOCORTICOIDS
HORMONES
HYDROXY COMPOUNDS
INJECTION
INTAKE
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KETONES
MAMMALS
NEOPLASMS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PREGNANES
PROTEINS
RADIOISOTOPES
RODENTS
STEROID HORMONES
STEROIDS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques
550901 - Pathology- Tracer Techniques