Effects of beta-adrenergic blockade or stimulation on net rate of hydrothorax absorption.
We determined in anesthetised rabbits the net rate of liquid absorption (NRLA) from Ringer or 1% albumin-Ringer hydrothoraces with the beta-blocker propranolol (or nadolol) or the beta-agonist terbutaline. The beta-blocker reduced NRLA by 38% in 2 ml Ringer hydrothoraces, and did not change it in 2 ml albumin-Ringer hydrothoraces; hence, with beta-blocker NRLA became similar in both kinds of hydrothorax (0.31 +/- 0.02 ml/h). Terbutaline decreased NRLA by 25% in 2 ml Ringer hydrothoraces, and increased it by 29% in 2 ml albumin-Ringer hydrothoraces; hence, with terbutaline NRLA became similar in both kinds of hydrothorax (0.40 +/- 0.02 ml/h), and 25% higher than with beta-blocker. Because beta-adrenoreceptor activity inhibits lymphatic smooth muscles and may increase Na+ transport in epithelia, these results suggest that: (1) pleural mesothelium is provided with beta-receptors, which increase Na+ transport and seem activated by protein dilution, (2) beta-receptors of the pleural lymphatics are essentially silent with and without protein dilution, (3) the lymphatic drainage produced by smooth muscle activity is smaller than the increase in solute-coupled liquid absorption caused by mesothelium beta-receptors.
Istituto di Fisiologia Umana I, Università di Milano, Italy.
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Agostoni
D000042:Absorption / Q000187:drug effects; D000818:Animals; D006876:Hydrothorax / Q000188:drug therapy / Q000503:physiopathology*; D008208:Lymphatic System / Q000187:drug effects / Q000503:physiopathology; D009130:Muscle, Smooth / Q000187:drug effects / Q000503:physiopathology; D009248:Nadolol / Q000494:pharmacology; D010994:Pleura / Q000187:drug effects / Q000503:physiopathology; D011433:Propranolol / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013726:Terbutaline / Q000494:pharmacology
D011506:Proteins; D011943:Receptors, Adrenergic, beta; D009248:Nadolol; D011433:Propranolol; D013726:Terbutaline