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

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 either 5 per cent CO2 in air or 100 per cent O2. Changes in Fg values during inhalation of 5 per cent CO2 were used to estimate cerebral vasodilator capacitance, and those during inhalation of 100 per cent O2 were used to estimate cerebral vasoconstrictor capacitance. Results indicated that chronic cigarette smokers have both reduced vasodilator (P less than 0.01) and reduced vasoconstrictor (P less than 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 per cent CO2 inhalation was reduced among smokers compared with nonsmokers of the same age by 48 per cent in non-risk subjects and 56 per cent in risk-factored subjects, while vasoconstrictor capacitance to 100 per cent O2 inhalation among smokers was decreased by 24 per cent in non-risk subjects and 34 per cent in risk-factored subjects. In risk-factored subjects, combined effects of smoking and other risks appeared to be additive.

Visually evoked cerebral vasomotor response in smoking and nonsmoking young adults, investigated by functional transcranial Doppler

“…Impaired vasodilation may lead to compromised cerebral hemodynamics even at an earlier stage of carotid stenosis or at lower cerebral perfusion pressures, causing cerebral ischemia (Vernieri, capacity may result in progression of ischemic damage in the penumbra, leading to worse outcomes. Thus, impairment of cerebral vasomotor reactivity, demonstrated by this and previous studies (Rogers et al, 1984), could act together with atherosclerosis and may influence stroke occurrence and outcome in chronic smokers.…”

“…Using a Xe inhalation method, Rogers et al (1984) reported worse vasodilator and vasoconstrictor reactivity in chronic smokers to 5% CO 2 and 100% O 2 , respectively. Quite to the contrary, others did not find significant difference in the vasomotor reactivity, when the chronic effect of cigarette smoking was assessed by breath holding test, between healthy smokers and age-matched controls (Silvestrini et al, 1996;Terborg et al, 2002).…”

“…Basal cerebral blood flow (CBF) in chronic smokers (Kubota et al, 1983;Rogers et al, 1983;Rogers, Meyer, Judd & Mortel, 1985;Yamashita, Kobayashi & Yamaguchi, 2000), as well as acute effect of cigarette smoking on CBF (Wennmalm, 1982;Boyajian & Otis, 2000;Terborg, Bramer, Weiller & Rother, 2002) were examined in humans. However, only few studies have investigated the chronic effects of cigarette smoking on cerebral vasomotor reactivity and reported contradictory results (Rogers, Meyer, Shaw, Mortel & Thornby, 1984;Silvestrini, Troisi, Matteis, Cupini & Bernardi, 1996;Terborg et al, 2002). Whether smokers have impaired cerebral vasodilatory mechanism is an important question since it might contribute to increased stroke risk and worse outcome in cerebral ischemia.…”

Additional predisposing risk factors for atherothrombotic cerebrovascular disease among treated hypertensive volunteers.

“…Human studies in which CBF was measured as the indicator of cerebral atherosclerosis have demonstrated that cigarette smoking significantly reduces cerebral perfusion 2627 as well as cerebrovascular reactivity tested by inhalation of O 2 or 5% CO2. 28 Abstinence from cigarette smoking in this population was later shown to improve cerebral perfusion. 29 Results of the present study provide stronger and more significant relations between cigarette smoking and occlusive CVD (including stroke, TIAs, and MID).…”

Chronic smoking and the BOLD response to a visual activation task and a breath hold task in patients with schizophrenia and healthy controls

“…It is known that smokers have reduced cerebral blood flow (CBF) (Rogers et al, 1984;Isaka et al, 1993). Decreased CBF should also increase oxygen extraction during capillary transit.…”