Abstract
The type II pneumocyte secretes surfactant phospholipid in response to beta-adrenergic stimulation. These studies identify the beta-adrenergic cell membrane receptors which mediate this response. The receptors were studied using radiolabeled (3H) dihydroalprenolol (DHA), a beta-adrenergic antagonist with high affinity for receptor sites. Assays were performed on intact type II pneumocytes freshly isolated from adult rabbits. The reaction was performed in .154M Krebs Ringers Phosphate containing 0.2% bovine serum albumin and 200μM Na-metabisulfite. The assay reaction required inclusion of 100μM phentolamine to minimize nonspecific binding. In the presence of phentolamine, specific receptor binding was indicated by displacement of DHA by 6μM propanolol. The receptor displayed stereospecificity for the (−) isomer of propanolol. The receptor assay reached equilibrium within five minutes and remained stable for at least 20 minutes. Receptor sites were quantitatively related to the number of cells per reaction. Saturation kinetics was demonstrated. Scatchard plot analysis of data revealed only one class of beta-adrenergic receptors and approximately 105 receptors per cell. These studies have established conditions for analysis of the beta-adrenergic receptors of intact type II pneumocytes and provided a preliminary characterization. Further study of these beta-adrenergic receptors will help elucidate regulation of the pulmonary surfactant system.
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Shapiro, D., Finkelstein, J. 1723 THE BETA-ADRENERGIC RECEPTOR OF THE TYPE II PNEUMOCYTE. Pediatr Res 15 (Suppl 4), 730 (1981). https://doi.org/10.1203/00006450-198104001-01742
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DOI: https://doi.org/10.1203/00006450-198104001-01742