The Effects of Chronic Cigarette Smoking on Cerebrovascular Responsiveness to 5 Per Cent CO2 and 100 Per Cent O2 Inhalation

Publisher Website
Google Scholar
Abstract
Effects of chronic cigarette smoking on cerebrovascular responsiveness of volunteers at risk for stroke and not at risk for stroke were evaluated by serial measurements of cerebral blood flow using the 133Xe inhalation method. Resting gray matter blood flow values (Fg) measured while breathing room air were compared with Fg values measured during inhalation of 5% CO2 in air or 100% O2. Changes in Fg values during inhalation of 5% CO2 were used to estimate cerebral vasodilator capacitance, and those during inhalation of 100% O2 were used to estimate cerebral vasoconstrictor capacitance. Results indicated that chronic cigarette smokers have reduced vasodilator (P < 0.01) and reduced vasoconstrictor (P < 0.02) capacitance when compared with nonsmokers of the same ages regardless of whether or not other risk factors for stroke were present. Vasodilator capacitance to 5% CO2 inhalation was reduced among smokers compared with nonsmokers of the same age by 48% in non-risk subjects and 56% in risk-factored subjects, while vasoconstrictor capacitance to 100% O2 inhalation among smokers was decreased by 24% in non-risk subjects and 34% in risk-factored subjects. In risk-factored subjects, combined effects of smoking and other risks appeared to be additive.