Dexamethasone effects on vascular volume and tissue hematocrit in experimental RG-2 gliomas and adjacent brain |
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Authors: | Hidemitsu Nakagawa Dennis R Groothuis Ernest S Owens Clifford S Patlak Karen D Pettigrew Ronald R Glasberg |
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Institution: | (1) Nuclear Medicine Department, National Institutes of Health, 20892 Bethesda, MD, USA;(2) Department of Neurology, Northwestern University, Evanston Hospital, 60201 Evanston, IL, USA;(3) Theoretical Statistics and Mathematics Branch, Institute of Mental Health, National Institute of Health, 20892 Bethesda, MD, USA;(4) Present address: Department of Neurosurgery, Osaka University Medical School, 1-1-50, Fukushima, Fukushima, 553 Osaka, Japan;(5) Present address: Department of Neurological Surgery, State University of New York at Stony Brook, 11794 Story Brook, NY |
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Abstract: | Summary We have studied the effects of dexamethasone, a corticosteroid commonly used to treat brain tumors, on vascular volume and
tissue hematocrit in RG-2 experimental rat gliomas.125I-RISA (radioiodinated serum albumin) was used to measure tissue plasma vascular volume (Vp) and51Cr labeled red cells were used to measure tissue red cell volume (Vrbc). Quantitative autoradiography was used to obtain local measurements of Vp and Vrbc in different brain and tumor regions. From these experimentally measured values, we calculated the tissue vascular volume
(Vv), tissue hematocrit (THct) and systemic arterial hematocrit (AHct). The value reported primarily reflect capillary and small
vessel volumes since blood drained from larger vessels during tissue processing and large vascular structures were avoided
during analysis of the autoradiographic images. A total of 110 tumors were studied in 29 animals. There was a consistent trend
for Vp and Vv to be reduced in all tumor regions after dexamethasone treatment, although a significant decrease was seen only in tumor
center. Dexamethasone did not affect Vp or Vv in tumor-free brain regions. Dexamethasone appeared to have little effect on Vrbc in any brain or tumor region. THct was consistently, although not significantly, higher in tumors after treatment with dexamethasone;
THct in tumor-free brain regions was unaffected by dexamethasone treatment. |
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Keywords: | brain tumors vascular volume dexamethasone gliomas tissue hematocrit RISA |
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