Based on the findings of decreased vital capacity, decreased FEV1 and increased closing volume after ascent to high altitude, some investigators suggest the presence of a subclinical high altitude pulmonary edema (HAPE). Since these parameters are only indirect measures of pulmonary interstitial fluid accumulation, the aim of this study is to examine the effects of broncho-constriction on the increase of closing volume by extensive lung function testing in healthy mountaineers at low altitude and on the Margherita Hut (4559 m). As has been done in earlier studies, conventional thorax radiographs are used for verification of HAPE. In this study, the determination of the thoracic fluid quantity will be completed by measurements of thoracic impedance. In addition markers of pulmonary endothelial function will be assessed to get further insight into the regulation of pulmonary vascular tone at altitude and in particular into the pathophysiology of HAPE.

Inclusion Criteria:

• Mountaineering ability required for reaching the Margherita hut (4559 m)

Exclusion Criteria:

• Borne above 1500 m
• Subjects with internal medical diseases like all cardiac diseases, all pulmonary diseases, Diabetes mellitus, infectious diseases, thyroid diseases, malignant diseases, hepatic or renal diseases,
• (Known) hypersensitivity to salbutamol or to another component of sultanol® or lidocaine, or to another component of xylocain® pump spray
• Intake of drugs, especially nifedipine, acetazolamide and glucocorticoids or of drugs interacting with sultanol® or xylocain® pump spray
• Pregnancy