Assessing microcirculation in familial dysautonomia by laser Doppler flowmeter

Area of Science:

• Cardiovascular Physiology
• Neuroscience
• Pharmacology

Background:

• Familial dysautonomia (FD) is a genetic disorder affecting the autonomic nervous system.
• Microcirculatory dysfunction is implicated in various autonomic disorders.
• Adrenergic receptor function plays a critical role in regulating vascular tone.

Purpose of the Study:

• To investigate microcirculatory vasomotor responses to alpha-adrenergic stimulation and blockade in familial dysautonomia.
• To compare these responses between FD patients and healthy controls.
• To explore potential mechanisms underlying vascular dysregulation in FD.

Main Methods:

• Laser Doppler flowmetry was used to measure skin blood flow in midclavicular areas.
• Iontophoresis delivered an alpha-antagonist (phentolamine) and an alpha-agonist (norepinephrine) or saline control.
• Blood flow changes were continuously monitored during and after drug administration.

Main Results:

• Familial dysautonomia subjects had higher baseline perfusion and more fluctuating baselines.
• Saline iontophoresis increased perfusion in controls but not significantly in FD subjects.
• Phentolamine pretreatment identified two subgroups of FD subjects: responders and non-responders.
• Norepinephrine consistently decreased blood flow in both groups, but the constrictive response was less pronounced in FD subjects.

Conclusions:

• Higher baseline perfusion in FD suggests intrinsic vascular dilation.
• Some FD subjects display impaired vasodilator responses to alpha-antagonist.
• Reduced microcirculatory constrictive response to alpha-agonist in FD indicates potential adrenoceptor dysfunction or decreased innervation.