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Heightened norepinephrine-mediated vasoconstriction in type 2 diabetes
R V Hogikyan1, A T Galecki, J B Halter
1Department of Internal Medicine, and Institute of Gerontology, University of Michigan, Ann Arbor, USA.
Metabolism: Clinical and Experimental
|December 22, 1999
Summary
People with type 2 diabetes have increased arterial adrenergic responsiveness, even without high blood pressure. This heightened response occurs independently of their overall sympathetic nervous system activity levels.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Metabolic Disorders
Background:
- Adrenergic responsiveness (AR) is elevated in diabetes.
- Arterial AR in normotensive individuals with type 2 diabetes mellitus is not well-documented.
- Understanding arterial AR is crucial for managing cardiovascular complications in diabetes.
Purpose of the Study:
- To investigate if arterial AR is increased in type 2 diabetes compared to controls.
- To examine the relationship between arterial AR and systemic sympathetic nervous system activity (SNSa).
Main Methods:
- Studied 15 type 2 diabetic and 13 age-matched control subjects.
- Assessed vascular alpha-AR via forearm blood flow during norepinephrine and phentolamine infusions.
- Measured plasma norepinephrine levels and norepinephrine release rate as indicators of SNSa.
Main Results:
- Norepinephrine-induced vasoconstriction was greater in type 2 diabetes patients.
- Phentolamine-induced vasodilation was greater, indicating increased endogenous alpha-adrenergic tone.
- Plasma norepinephrine and norepinephrine release rates were similar between groups, suggesting comparable SNSa.
Conclusions:
- Type 2 diabetes is associated with heightened arterial alpha-adrenergic responsiveness.
- This increased responsiveness is disproportionate to the level of systemic sympathetic nervous system activity.
- Findings suggest a potential mechanism for cardiovascular dysfunction in type 2 diabetes.