Abstract
Quantitation using tissue homogenates has demonstrated an increase in pulmonary β-receptors during development. However, techniques using disrupted tissue have not permitted the precise anatomic localization of pulmonary β-receptors or identification of the structures where increases occur. Using 3H-dihydroalprenolol, β-receptors were radioautographically localized and quantitated in sections of newborn (NB) and adult (A) guinea pig lung. Specific binding on lung sections, defined as that prevented by 2μ M propranolol (80-90% of total counts), was rapid and saturable. Scatchard analysis showed a single class of binding sites with a maximum binding capacity of 189±3 (NB) and 305±37 (A) fmole/mg protein (p<.003). Binding was of high affinity Kd = 1.46±.2 (NB) 1.26±.3 (A) nM (N.S.). The majority of β-receptors were localized in the alveolar wall and airway epithelium (alveolar >> bronchiolar > bronchial) (p<.0001) and averaged 2.8 (A) and 1.3 (NB)-fold greater in number than β-receptors in corresponding airway smooth muscle (p<.005). Arterial and venous smooth muscle had few demonstrable β-receptors. The increased number of β-receptors in the adult appeared to be due primarily to a 2.0±.2 fold increase in alveolar wall and airway epithelium as opposed to only a 1.3±.4 fold increase in the already low number in airway and vascular smooth muscle (p<.003). While receptor density may not necessarily correlate with response or physiologic importance, the role of β-receptors in airway and alveolar epithelium/endothelium function deserves further investigation.
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Gatto, C., Seybold, V., Kulik, T. et al. ANATOMIC DISTRIBUTION AND QUANTITATIVE DEVELOPMENTAL CHANGES IN GUINEA PIG PULMONARY BETA RECEPTORS. Pediatr Res 18 (Suppl 4), 138 (1984). https://doi.org/10.1203/00006450-198404001-00268
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DOI: https://doi.org/10.1203/00006450-198404001-00268