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Updated: Jan 20, 2026
Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
The effects of spaceflight on adrenergic receptors and agonists and cell adhesion molecule expression
Paul J Mills1, Christy J Perez, Karen A Adler
1Department of Psychiatry and Medicine, University of California, San Diego, La Jolla, CA 92103, USA. pmills@ucsd.edu
Abstract:
Twenty-two astronauts who flew aboard 10 different US Space Shuttle flights were studied 10 days before launch, on landing day, and 2-4 days post-landing. After landing, plasma levels of norepinephrine (p<0.01) were elevated. Lymphocyte beta(2)-adrenergic receptors were desensitized 2-4 days post-landing (p<0.02). The density of CD62L on lymphocytes was unchanged but the densities of CD11a (p<0.01) and CD54 (p<0.001) were down-regulated. CD11a density was also down-regulated on monocytes (p<0.01). Neutrophils showed an up-regulation of CD11a (p<0.01) and a down-regulation of CD54 (p<0.01). CD11a density on neutrophils remained up-regulated (p<0.01) and CD54 density remained down-regulated (p<0.01) at 2-4 days post-landing. Circulating levels of soluble ICAM-1 (CD54) and soluble E-selectin (CD62E) were decreased after landing (p's<0.05). The data suggest that spaceflight leads to an environment that would support reduced leukocyte-endothelial adhesion. Sympathetic activation may contribute to this phenomenon.
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