title: Distention-produced phospholipid secretion in postmortem in situ lungs of newborn rabbits. Inhibition by specific beta-adrenergic blockade.
abstract: The secretion of total phospholipid in postmortem in situ lungs of newborn rabbits was examined using the technique of lung lavage after an initial lavage procedure, and then after a period of static air inflation at 30 cm H2O pressure for 45 min. There was a significant reduction in the phospholipid yield with 10(-3) molar DL-propranolol used as the initial lavage fluid, both immediately after the initial lavage procedure (experimental group, 0.29 +/- SE 0.04 mg/g dry lung weight; control group, 0.57 +/- SE 0.09; p less than 0.01) and after static inflation with air (experimental group, 1.14 +/- SE 0.15; control group, 2.22 +/- SE 0.24; p less than 0.001). Preinjection of the breathing newborn rabbit with DL-propranolol was not necessary for this inhibitory effect. There was no significant reduction when 10(-3) molar atropine, lidocaine, D-propranolol, or 10(-5) scopolamine were substituted as the initial lavage fluid, nor was there any reduction when the concentration of DL-propranolol was decreased to 10(-4) or 10(-5) molar. Because D-propranolol has all the properties of DL-propranolol, except 100-fold less beta-adrenergic antagonist activity, the inhibition by propranolol was due to specific beta-adrenergic blockade. In the absence of an intact circulation or a functional central nervous system, it is concluded that surfactant phospholipid secretion is partly controlled by an intrapulmonary neurogenic reflex.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D005260:Female; D008168:Lung / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D011247:Pregnancy; D011433:Propranolol / Q000494:pharmacology; D011663:Pulmonary Surfactants / Q000378:metabolism*; D011817:Rabbits; D007507:Therapeutic Irrigation
chemical_list: D010743:Phospholipids; D011663:Pulmonary Surfactants; D011433:Propranolol