Inhibition of gastrointestinal mucosal glycoprotein synthesis by the beta-adrenergic blocking drug, practolol

The effect of administration of practolol and other beta-blocking agents on gastrointestinal mucosal glycoprotein synthesis was studied in the rat. Practolol, at a dose of 50 mg/kg, inhibited the incorporation of N-acetylglycosamine into gastric mucosal glycoproteins, while acebutolol, atenolol, pronethalol and propranolol had no inhibitory effect, even at a dose of 200 mg/kg. In addition, practolol inhibited the incorporation of N-acetylneuraminic acid, D-fucose and L-serine into gastric mucosal glycoproteins, while the other beta-blocking agents had no effect. Administration of practolol caused no significant change in the rate of incorporation of glycoprotein precursors into intestinal mucosal glycoproteins. These results indicate that of the beta-blocking drugs studied, inhibition of glycoprotein synthesis is associated only with practolol and is independent of its beta-blocking effect.