Selected Contribution: Long-term effects of β2-adrenergic receptor stimulation on alveolar fluid clearance in mice

C Sartori, X Fang, DW McGraw… - Journal of Applied …, 2002 - journals.physiology.org
C Sartori, X Fang, DW McGraw, P Koch, ME Snider, HG Folkesson, MA Matthay
Journal of Applied Physiology, 2002journals.physiology.org
Stimulation of active fluid transport with β-adrenergic receptor (βAR) agonists can accelerate
the resolution of alveolar edema. However, chronic βAR-agonist administration may cause
βAR desensitization and downregulation that may impair physiological responsiveness to
βAR-agonist stimulation. Therefore, we measured baseline and terbutaline-(10− 3 M)
stimulated alveolar fluid clearance in mice that received subcutaneously (miniosmotic
pumps) either saline or albuterol (2 mg· kg− 1· day− 1) for 1, 3, or 6 days. Continuous …
Stimulation of active fluid transport with β-adrenergic receptor (βAR) agonists can accelerate the resolution of alveolar edema. However, chronic βAR-agonist administration may cause βAR desensitization and downregulation that may impair physiological responsiveness to βAR-agonist stimulation. Therefore, we measured baseline and terbutaline- (10−3 M) stimulated alveolar fluid clearance in mice that received subcutaneously (miniosmotic pumps) either saline or albuterol (2 mg · kg−1 · day−1) for 1, 3, or 6 days. Continuous albuterol administration increased plasma albuterol levels (10−5 M), an effect that was associated with 1) a significant decrease in βAR density and 2) attenuation, but not ablation, of maximal terbutaline-induced cAMP production. Forskolin-mediated cAMP-release was unaffected. Continuous albuterol infusion stimulated alveolar fluid clearance on day 1 but did not increase alveolar fluid clearance on days 3 and 6. However, terbutaline-stimulated alveolar fluid clearance in albuterol-treated mice was not reduced compared with saline-treated mice. Despite significant reductions in βAR density and agonist-mediated cAMP production by long-term βAR-agonist exposure, maximal βAR-agonist-mediated increase in alveolar fluid clearance is not diminished in mice.
American Physiological Society