The goal is to determine mechanisms for abnormal vascular reactivity in diabetes mellitus. The hypothesis is that the hyperglycemic milieu leads to dysfunction of endothelial cells and sympathetic nerves within blood vessels, which then abnormally regulate vascular smooth muscle contraction. Studies demonstrated that the endothelium-dependent relaxation to acetylcholine of diabetic aorta is impaired. The normal relaxation by endothelium-derived relaxing factor is counteracted by the production by diabetic endothelial cells of vasoconstrictor prostanoids including thromboxane Az. The abnormal endothelial cell function is likely due to hyperglycemia, because the endothelium of normal aorta exposed to high glucose concentrations also responds abnormally by producing vasoconstrictor prostanoids. Preliminary studies indicate that cultured aortic endothelial cells exposed to elevated glucose will provide a useful mode in which to identify bioassayable endothelium-derived vasoconstrictor prostanoids. Prostanoids including 6-keto-PGF1a, thromboxane B2, PGF2a, PGE2, and 15-HETE will be measured by radioimmunoassay, and radiochromatography will be used to analyze metabolic products of 14C- arachidonic acid to identify the vasoconstrictors involved. Neuropathic changes were also found in diabetic rabbit arteries with reduced quantities and abnormal release of norepinephrine with reduced prejunctional inhibition by the endothelium. The modulation of endogenous norepinephrine release from adrenergic nerves and metabolism by diabetic endothelium will be investigated. The proposed studies will pursue the physiological mechanisms of the altered endothelial cell and adrenergic nerve function in arteries from diabetic rabbits and normal arteries exposed to high glucose. Evidence will be sought for abnormal aldose reductase activity, myo- inositol levels, g-proteins, protein kinase C, and Na/K ATPase. Because of the importance of microvascular disease in diabetes, new studies are proposed to study reactivity of isolated coronary and mesenteric microvessels, and resistance vessels in perfused hearts.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL038731-08
Application #
2219014
Study Section
Cardiovascular and Renal Study Section (CVB)
Project Start
1990-09-01
Project End
1996-08-31
Budget Start
1994-09-01
Budget End
1996-08-31
Support Year
8
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Boston Medical Center
Department
Type
DUNS #
005492160
City
Boston
State
MA
Country
United States
Zip Code
02118
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Khan, F; Cohen, R A; Ruderman, N B et al. (1996) Vasodilator responses in the forearm skin of patients with insulin-dependent diabetes mellitus. Vasc Med 1:187-93
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Stegeman, J J; Hahn, M E; Weisbrod, R et al. (1995) Induction of cytochrome P4501A1 by aryl hydrocarbon receptor agonists in porcine aorta endothelial cells in culture and cytochrome P4501A1 activity in intact cells. Mol Pharmacol 47:296-306
Cohen, R A (1995) The role of nitric oxide and other endothelium-derived vasoactive substances in vascular disease. Prog Cardiovasc Dis 38:105-28
Tesfamariam, B; Cohen, R A (1995) Enhanced adrenergic neurotransmission in diabetic rabbit carotid artery. Cardiovasc Res 29:549-54
Tesfamariam, B; Brown, M L; Cohen, R A (1995) 15-Hydroxyeicosatetraenoic acid and diabetic endothelial dysfunction in rabbit aorta. J Cardiovasc Pharmacol 25:748-55
Najibi, S; Cowan, C L; Palacino, J J et al. (1994) Enhanced role of potassium channels in relaxations to acetylcholine in hypercholesterolemic rabbit carotid artery. Am J Physiol 266:H2061-7
Cayatte, A J; Palacino, J J; Horten, K et al. (1994) Chronic inhibition of nitric oxide production accelerates neointima formation and impairs endothelial function in hypercholesterolemic rabbits. Arterioscler Thromb 14:753-9

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