We plan to investigate the acute effects of inhaling e-cigarette vapor on cell function measured by microvesicles and endothelial progenitor cells. Micro vesicles are released upon either activation or apoptosis from different cell types such as platelets, leucocytes and endothelial cell. Endothelial progenitor cells are a type of stem cells that circulate in the blood with the ability to differentiate to endothelial cells. Endothelial progenitor cells are inversely correlated to cardiovascular risk factors.

As a secondary endpoint we plan to investigate exhaled nitric oxide - a common inflammation marker used in asthmatic patients - after inhalation of electronic cigarette vapor.

Inclusion Criteria:

• healthy subjects
• sporadic cigarette smoking (<9 cigarettes per month)

Exclusion Criteria:

• Any form of cardiovascular disease
• Any form of pulmonary disease like asthma or COPD
• Any form of systemic or chronic disorder like rheumatologic or metabolic diseases.
• Active allergy within 4 weeks of the study
• Symptoms of infection or inflammation within 4 weeks of the study
• Pregnancy