23. september 2003 

Prolonged acetylcholine-induced vasodilatation in the peripheral
microcirculation of patients with chronic fatigue syndrome

Clin Physiol Funct Imaging 2003; 23(5): 282-285

Institution: Faisel Khan, Vance Spence, Gwen Kennedy and Jill J. F.
Belch, Vascular Diseases Research Unit, Department of Medicine,
University of Dundee, Dundee, UK.

This new scientific paper in Clinical Physiology and Functional Imaging
publishes research that shows prolonged vasodilatation in response to
acetylcholine delivered to skin blood vessels. These results represent a
further step in the MERGE-funded investigations of disturbances to
cholinergic pathways and the vascular endothelium of patients with
ME/CFS.

Background: Although the aetiology of chronic fatigue syndrome (CFS) is
unknown, there have been a number of reports of blood flow abnormalities
within the cerebral circulation and systemic blood pressure defects
manifesting as orthostatic intolerance. Neither of these phenomena has
been explained adequately, but recent reports have linked cerebral
hypoperfusion to abnormalities in cholinergic metabolism. Our group has
previously reported enhanced skin vasodilatation in response to
cumulative doses of transdermally applied acetylcholine (ACh), implying
an alteration of peripheral cholinergic function.

Methods and Results: To investigate this further, we studied the time
course of Ach-induced vasodilatation following a single dose of ACh in
30 patients with CFS and 30 age and gender-matched healthy control
subjects. No differences in peak blood flow were seen between patients
and controls, but the time taken for the ACh response to recover to
baseline was significantly longer in the CFS patients than in control
subjects. The time taken to decay to 75% of the peak response in
patients and controls was 13.7±11.3 vs. 8.9±3.7 min (P=0.03),
respectively, and the time taken to decay to 50% of the peak response
was 24.5±18.8 vs. 15.1±8.9 min (P=0,03), respectively.

Conclusions: Prolongation of ACh-induced vasodilatation is suggestive of
a disturbance to cholinergic pathways, perhaps within the vascular
endothelium of patients with CFS, and might be related to some of the
unusual vascular symptoms, such as hypotension and orthostatic
intolerance, which are characteristic of the condition.