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Increased alpha2-adrenergic constriction of isolated arterioles in diffuse scleroderma
N A Flavahan1, S Flavahan, Q Liu
1Heart and Lung Institute, Ohio State University, Medical Research Facility, Columbus, OH 43210, USA.
Arthritis and Rheumatism
|August 16, 2000
Summary
Systemic sclerosis (SSc) arterioles show increased alpha2-adrenergic receptor (alpha2-AR) reactivity, contributing to vasospasm. Endothelial function remains normal in SSc patients, suggesting smooth muscle alterations are key in this scleroderma feature.
Area of Science:
- Vascular biology
- Rheumatology
- Dermatology
Background:
- Systemic sclerosis (SSc), or scleroderma, is characterized by vasospasm and ischemic organ injury.
- Understanding the intrinsic vascular dysfunction in SSc is crucial for managing the disease.
Purpose of the Study:
- To investigate intrinsic vasoconstrictor activity disturbances in dermal arterioles of patients with SSc.
- To determine if SSc arterioles exhibit abnormal responses to specific vasoconstrictors.
Main Methods:
- Dermal arterioles were isolated from skin biopsies of 11 SSc patients and 8 controls.
- Arteriolar diameter was monitored using a myograph to assess vasoconstriction.
- Reactivity to receptor-independent (KCl) and receptor-dependent agonists (phenylephrine, UK 14,304) was tested.
Main Results:
- SSc and control arterioles showed similar basal diameter and constriction to KCl and phenylephrine (alpha1-AR agonist).
- SSc arterioles exhibited significantly enhanced constriction to UK 14,304, a selective alpha2-AR agonist.
- Endothelial denudation and testing with acetylcholine/bradykinin confirmed normal endothelial dilator function in SSc.
Conclusions:
- SSc dermal arterioles display a selective increase in alpha2-AR reactivity in vascular smooth muscle.
- Normal endothelial dilator function suggests altered alpha2-AR activity contributes to SSc-related vasospasm.
- These findings highlight a potential therapeutic target in managing SSc vascular complications.