Preventive effect of varenicline on impairment of endothelial function in cerebral vessels induced by acute smoking in rats
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Preoperative smoking cessation is important for recovery from surgery without complications. Available evidence suggests nicotine replacement therapy could be safe and effective in the perioperative period. On the other hand, the newly developed selective nicotinic acetylcholine (ACh) receptor partial agonist, varenicline tartrate, is also effective as an aid for smoking cessation and helps people to stop smoking. During the transitional phase between the decision to stop smoking and actual smoking cessation, patients could use varenicline before undertaking smoking cessation. We have previously reported that acute cigarette smoking can cause impairment of endothelium-dependent vasodilation in cerebral vessels; thus, the use of varenicline before surgery in a patient who is still a smoker may not be safe with regard to endothelial function. Therefore, to assess the safety of varenicline in terms of endothelial function, we evaluated its effect on the acute smoking-induced impairment of endothelium-dependent cerebral vasodilation. In anesthetized Sprague–Dawley rats, we applied ACh topically to pial vessels; then, after administering intravenous varenicline or saline injection, we reexamined the ACh-induced vasodilator response both before and after smoking. Under control conditions, cerebral pial arterioles were dose-relatedly dilated by ACh. After smoking, 10−5 M ACh constricted the arterioles following saline pretreatment (diameter −7.6 ± 1.8 %, n = 6), but induced dilation following varenicline pretreatment (diameter +15.3 ± 3.3 %, n = 6). Thus, varenicline may prevent the smoking-induced impairment of endothelium-dependent vasodilation in cerebral pial arterioles.