Effects of propranolol, pindolol and atenolol after multiple administration in rats on the duration of hexobarbital sleeping time and on the activity of some drug-metabolizing enzyme systems.

Three beta-adrenergic blocking agents propranolol (50 mg/kg), pindolol (5mg/kg) and atenolol (150mg/kg) were administered orally in rats for 21 days. The duration of hexobarbital (HB) sleeping time and the activities of some liver monooxygenases and synthetases were studied. The HB sleeping time was not changed. Propranolol and pindolol decreased the ethylmorfin-N-demethylase (EMND) and benzphetamine-N-demethylase (BND) activities. The three beta-adrenergic blocking agents did not change the activities of anilinehydroxylase (AH), ethoxycoumarine-O-demethylase (ECOD), and glutathione-S-transferase (G-S-T), the total content of cytochrome P-450, b5 and microsomal heme. They increased the activities of uridinediphosphoglucuronil transferase (UDPGT) and NADPH-cytochrome C reductase. The participation of different mechanisms of the effects of the three beta-adrenergic blocking agents on the activity of drug-metabolizing enzyme systems was discussed.