Acute Effect of Aliskiren on Smoking-Induced Endothelial Dysfunction in Smoker

Abstract

Background: We aimed to examine the acute effect of aliskiren on smoking-induced endothelial dysfunction in smoker.Methods: Nineteen male smokers were enrolled. After all participants smoked a cigarette, their endothelial function was assessed with brachial artery flow mediated dilation (FMD). An hour after the administration of aliskiren, they smoked again, their FMD was assessed again. A month later, all measurements were performed again without the administration of aliskiren as a control. Blood pressure, plasma renin activity, and serum interleukin-6 concentration were also examined at the same time of FMD measurement.Results: A cigarette smoking led to an acute endothelial dysfunction (6.5 ± 1.7% to 3.4 ± 1.0 %, P = 0.02). Aliskiren administration significantly suppressed blood pressure and plasma renin activity, furthermore, improved FMD (6.7 ± 0.5% to 8.1 ± 0.8 %, P = 0.03). Aliskiren significantly reduced serum interleukin-6 concentration, but not in control. Conclusion:Aliskiren has a beneficial effect on smoking-induced acute endothelial dysfunction. MethodsThe study enrolled nineteen male smokers aged 41 ± 2 (27 to 51) years old that had no cardiovascular risk factors other than smoking. All measurements were performed in the early morning, before breakfast, refraining from smoking more than 12 hours. At first, each participant took two puffs of a cigarette which contained 8 mg of tar and 0.7 mg of nicotine. Immediately, endothelial function was assessed with brachial artery flow mediated dilation (FMD) using UNEXEF18G (UNEX Co.Nagoya, Japan) [13]. Then, all participants took a 150 mg of aliskiren. An hour later, following another two puffs of cigarette taken, FMD were evaluated again. Plasma renin activity, serum interleukin-6 (IL-6), thrombomodulin (TM) and asymmetric dimethylarginine (ADMA) concentration were examined before and an hour later. BP was also measured at supine position just before FMD measurement. A month later, all measurements were performed again without the administration of aliskiren as a control. This study was approved by Okayama University Institutional Review Board (accredited ISO9001/2000). All participants gave written consents. Data were presented as means ± SEM. Changes in parameters were evaluated by paired t test. Results with P < 0.05 were deemed statistically significant. ResultsAliskiren administration significantly reduced both systolic and diastolic BP (P < 0.01, each) without any change in pulse rate (Table 1). Plasma renin activity dramatically decreased in all