Objectives To investigate the endothelial function and carotid atherosclerosis in healthy school-aged Tibetan male adolescents.
Methods All participants with SHS were recruited through middle-school students with 16-year-old and male gender in Lhasa city. Totally 624 subjects were accepted after excluding active smoke subjects. All adolescents were divided into 2 groups according to serum cotinine level: high cotinine group (H-group) with 319 boys and low cotinine group (L-group) with 305 boys. Venous blood was sampled for the measurement of cotinine concentration, lipid profile and endothelin-1 (ET-1) quantitation. High-resolution B-mode ultrasonography was performed to evaluate carotid intima-media thickness (cIMT) and intima smoothness. The invasive vascular endothelial function was evaluated through the measurement of flow-mediated dilation (FMD) with B-mode ultrasound and ankle-brachial index (ABI) by using a blood pressure cuff and a Doppler instrument.
Results No statistical significance was found between groups in total cholesterol, HDL cholesterol, LDL cholesterol, triglyceride, ApoA-I, systolic blood pressure, diastolic blood pressure, and heart rate (P > 0.05). In the lipid profile, only ApoB values were different between groups: ApoB in H-group was higher than in L-group (P = 0.013). Plasma ET-1 concentrations in H-group were also much higher than in L-group (P < 0.001). The cIMT and intima smoothness deteriorated in H-group than in L-group (P < 0.001 and P < 0.05 respectively). FMD and ABI, which indicate vascular endothelial function, was decreased in H-group compared with L-group (FMD, P < 0.001; ABI, P < 0.001).
Conclusions SHS was associated with sub-clinical carotid atherosclerosis and endothelial dysfunction in Tibetan school-aged male adolescents. Considering the widespread exposure to SHS and the clinical relevance of early atherosclerosis, this result, is of public health importance in Tibet, where health education is not satisfied. Data from our study emphasise the importance of endorsing smoke-free environments for adolescents.