Effect of Acute Altitude Exposure on Serum Markers of Platelet Activation.

Background: Platelets are the key factor in primary hemostasis. It has been shown that chronic altitude exposure increases platelets' aggregability. Nevertheless, data about acute effects and the underlying mechanisms are sparse. Methods: Sixteen healthy volunteers were examined in our hospital (519 m alt.) and 30 minutes after arrival in the environmental research station on the Zugspitze Mountain (2656 m alt.). Serum levels of soluble p-selectin were examined to elucidate platelet activation. In addition, serum levels of chromogranin A (CGA) as a measure of adrenergic activation, endothelin 1 (ET-1) representing pulmonary vascular tone and monocyte chemoattractant protein-1 (MCP-1) as a measure of inflammatory response were examined. Results: Acute altitude exposure induced a significant increase of p-selectin (116 +/- 4.8 pg/mL vs. 132 +/- 6.2 pg/mL; p < 0.01). Whereas MCP-1 was significantly lowered (538 +/- 50.6 pg/mL to 470 +/- 41.1 pg/mL; p = 0.02) and CGA was not altered significantly (88 +/- 47.4 ng/mL vs. 79 +/- 44 ng/mL; p = 0.22), ET1 was increased significantly from 0.8 +/- 0.07 pg/mL to 1.15 +/- 0.09 pg/mL (p < 0.01). Conclusion: Our study could demonstrate relevant platelet activation that was accompanied by a 44% increase of ET-1. This activation might obtain clinical relevance in patients with pre-existing cardiovascular disease as a trigger for acute events.