In vivo and in vitro beta 2-adrenergic receptor responsiveness in young and elderly asthmatics
Hamelin, B.A.; Blouin, R.A.; Wolf, K.M.; Clifton, G.D.; Chandler, M.H.
PharmacoTherapy 12(5): 376-382
1992
ISSN/ISBN: 0277-0008 PMID: 1331993 Document Number: 398919
This pilot study was undertaken to characterize age-related alterations in airway and metabolic beta 2-adrenergic receptor response using terbutaline as a probe. A single dose of terbutaline 0.007 mg/kg was administered subcutaneously to 10 young (range 20-35 yrs) and 10 elderly (range 60-73 yrs) men and women with asthma. beta-Receptor function was assessed by serial pulmonary function tests, heart rate, blood pressure, plasma potassium, glucose, insulin, and catecholamine levels, and in vitro 3', 5'-cyclic adenosine monophosphate (cAMP) production of pure T lymphocytes. The trend was for lung beta 2-receptor response (bronchodilation) and T lymphocyte cAMP production to be lower in elderly than in young asthmatics, but differences did not reach statistical significance. Elderly subjects' beta 1-adrenergic receptor responsiveness (systolic blood pressure) was also dampened. These data suggest that T lymphocyte stimulation does reflect pulmonary beta 2-receptor response. Whether elderly asthmatics require and tolerate higher dosages of parenteral terbutaline than younger asthmatics deserves further study.