Felix W Wehrli1, Yongxia Zhou1, Zachary B Rodgers1, and Michael C Langham1
Smoking is well known to cause vasoconstriction as a
result of the formation of reactive oxygen species, which reduce nitric oxide
availability. Vasomotor reactivity can be measured in terms of the change in
cerebral blood flow in response to a hypercapnic challenge. Here we measured
the change in superior sagittal sinus flow at 2-second temporal resolution during
breath-hold (a predominantly hypercapnic stimulus) and computed a breath-hold
index (BHI) as the slope of the flow velocity-time curve in 20 nonsmokers and
13 chronic smokers. The data suggest reduced BHI in the smoking group (0.252±0.097
vs. 0.306±0.098 cm/s2, p<0.07) indicative of dysregulation of
vascular reactivity.
