The overall objectives of this project are twofold: first to examine the mechanisms responsible for alterations in cerebral microvascular hexose transport and fuel metabolism we have observed in the diabetic rat; and second to examine the relationship between these alterations and the regulation of myo- inositol transport, NaKATPase activity and polyol metabolism. The proposed studies will utilize intact rats, isolated microvessels and glomeruli and cultured microvascular cells.
The specific aims are as follows: 1). To determine the factors and mechanisms responsible for the downregulation of hexose transport across the blood-brain barrier (BBB) of diabetic rats. Hexose transport in vivo will be related to alterations in hexose transporter number, structure and (mRNA) in microvessels isolated from diabetic and other rats in which plasma insulin or glucose are chronically altered. 2). To examine the mechanism(s) by which hyperglycemia downregulates hexose (3-methylglucose) transport in cerebral microvascular endothelium (CMEC). The role of glucose metabolism and protein synthesis will be evaluated. Many of the parameters studied will be the same as those in Aim 1, thereby enabling us to compare the mechanism(s) by which hexose transport is downregulated in vivo in the diabetic rat and in vitro in CMEC grown in a glucose-enriched medium. 3). To determine the basis for upregulation of B-hydroxybutyrate transport across the BBB in diabetes and its relation to altered hexose transport. 4). To determine the functional consequences of altered transport and fuel metabolism in microvessels of diabetic rats. The ability to maintain myo-inositol and glutathione content, NaK ATPase activity and AIB transport will be assessed in microvessels from at least two sites and in isolated glomeruli. The effect of diabetes on O2 consumption and fuel metabolism in these tissues will also be examined. 5). To determine the effect of hyperglycemia on myo-inositol transport, polyol metabolism and NaK ATPase in CMEC and pericytes. These studies should provide fundamental information about the early metabolic and functional alterations produced by diabetes in the microvasculature and the mechanisms by which they occur. They will hopefully provide a groundwork for understanding the dysregulation of signal transduction in the microvasculature and for developing metabolically-based therapies to prevent the development of microvascular disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK039814-03
Application #
3239816
Study Section
Special Emphasis Panel (SSS (G))
Project Start
1988-08-01
Project End
1993-07-31
Budget Start
1990-08-01
Budget End
1991-07-31
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Boston University
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02118
Gupta, S; Yang, S; Cohen, R A et al. (1996) Altered contractility of urinary bladder in diabetic rabbits: relationship to reduced Na+ pump activity. Am J Physiol 271:C2045-52
Gupta, S; Phipps, K; Ruderman, N B (1996) Differential stimulation of Na+ pump activity by insulin and nitric oxide in rabbit aorta. Am J Physiol 270:H1287-93
Gupta, S; Moreland, R B; Munarriz, R et al. (1995) Possible role of Na(+)-K(+)-ATPase in the regulation of human corpus cavernosum smooth muscle contractility by nitric oxide. Br J Pharmacol 116:2201-6
Gupta, S; McArthur, C; Grady, C et al. (1994) Stimulation of vascular Na(+)-K(+)-ATPase activity by nitric oxide: a cGMP-independent effect. Am J Physiol 266:H2146-51
Gupta, S; McArthur, C; Grady, C et al. (1994) Role of endothelium-derived nitric oxide in stimulation of Na(+)-K(+)-ATPase activity by endothelin in rabbit aorta. Am J Physiol 266:H577-82
Sussman, I; Schultz, V; Gupta, S et al. (1993) Differential effect of metabolic fuels on the energy state and Na(+)-K(+)-ATPase in isolated cerebral microvessels. Am J Physiol 265:E777-82
Tesfamariam, B; Gupta, S; Oates, P J et al. (1993) Reduced Na(+)-K+ pump activity in diabetic rabbit carotid artery: reversal by aldose reductase inhibition. Am J Physiol 265:H1189-94
Schultz, V; Sussman, I; Bokvist, K et al. (1993) Bioluminometric assay of ADP and ATP at high ATP/ADP ratios: assay of ADP after enzymatic removal of ATP. Anal Biochem 215:302-4
Tornheim, K; Schultz, V (1993) Specific enzymatic spectrophotometric assay of adenosine 5'-diphosphate. Anal Biochem 211:329-30
Gupta, S; Sussman, I; McArthur, C S et al. (1992) Endothelium-dependent inhibition of Na(+)-K+ ATPase activity in rabbit aorta by hyperglycemia. Possible role of endothelium-derived nitric oxide. J Clin Invest 90:727-32

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